Previous Issue
Volume 11, May
 
 

Aerospace, Volume 11, Issue 6 (June 2024) – 59 articles

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Select all
Export citation of selected articles as:
24 pages, 30756 KiB  
Article
Computational Investigations for the Feasibility of Passive Flow Control Devices for Enhanced Aerodynamics of Small-Scale UAVs
by Ali Arshad and Vadims Kovaļčuks
Aerospace 2024, 11(6), 473; https://doi.org/10.3390/aerospace11060473 - 13 Jun 2024
Viewed by 227
Abstract
The 4R-UAV project aims to develop aerodynamically efficient and environmentally friendly UAVs based on the 4R Circular Economy principle. In this study, the feasibility of the application of PFCDs (Passive Flow Control Devices) was investigated for the small-scale low-speed 4R-UAV wing. The application [...] Read more.
The 4R-UAV project aims to develop aerodynamically efficient and environmentally friendly UAVs based on the 4R Circular Economy principle. In this study, the feasibility of the application of PFCDs (Passive Flow Control Devices) was investigated for the small-scale low-speed 4R-UAV wing. The application of PFCDs for small-scale UAV wings is relatively unexplored. Two PFCD types, i.e., MVGs (Micro Vortex Generators) and winglets, were considered for the investigations. In the stepwise investigations, the aerodynamic performance of the MVGs and the winglets was analyzed for the short-span 4R-UAV wing, which was developed from the aerodynamically optimized airfoil SG6043mod. MVGs enhanced the wings near stall properties (especially maximum lift coefficient) and contributed to the delayed wing stall of up to 2°. MVGs manifested the main aerodynamic advantage, which was achieved at the higher angles of attack. Winglets, on the other hand, were found to be extremely effective in cruise conditions with improved pre-stall characteristics. Extensive investigations on winglets were carried out by designing six winglet configurations for the 4R-UAV wing. Blended-type winglets performed well and enhanced pre-stall properties by decreasing the drag (up to 10%) of the wing. The main performance improvement was found in the early angles of attack. In the final step, the combined effect of the integrated PFCDs was analyzed. The final wing (integrated MVGs and winglets) also exhibited enhanced performance with nearly 6% increased lift-to-drag ratio in cruise conditions. The limited aerodynamic advantage achieved from the PFCDs in small-scale UAV applications can be useful in specific (civil or military) missions. Further verifications are planned in the future by means of experimental and flight testing. Full article
Show Figures

Figure 1

14 pages, 2769 KiB  
Article
A Joint Surface Contact Stiffness Model Considering Micro-Asperity Interaction
by Tian Xia, Jie Qu and Yong Liu
Aerospace 2024, 11(6), 472; https://doi.org/10.3390/aerospace11060472 - 12 Jun 2024
Viewed by 182
Abstract
Mechanical joint interfaces are widely found in mechanical equipment, and their contact stiffness directly affects the overall performance of the mechanical system. Based on the fractal and elastoplastic contact mechanics theories, the K-E elastoplastic contact model is introduced to establish the contact stiffness [...] Read more.
Mechanical joint interfaces are widely found in mechanical equipment, and their contact stiffness directly affects the overall performance of the mechanical system. Based on the fractal and elastoplastic contact mechanics theories, the K-E elastoplastic contact model is introduced to establish the contact stiffness model for mechanical joint interfaces. This model considers the interaction effects between micro-asperities in the fully deformed state, including elasticity, first elastoplasticity, second elastoplasticity, and complete plastic deformation state. Based on this model, the effects of fractal parameters on normal contact stiffness and contact load are analyzed. It can be found that the larger fractal dimension D or smaller characteristic scale coefficient G will weaken the interaction between micro-asperities. The smoother processing surfaces lead to higher contact stiffness in mechanical joint interfaces. The applicability and effectiveness of the proposed model are verified by comparing it with the traditional contact model calculation results. Under the same load, the interaction between micro-rough surfaces leads to an increase in both overall deformation and contact stiffness. The accuracy of the predicted contact stiffness model is also validated by comparing it with experimental results. Full article
Show Figures

Figure 1

27 pages, 849 KiB  
Review
A Critical Review of Information Provision for U-Space Traffic Autonomous Guidance
by Ivan Panov and Asim Ul Haq
Aerospace 2024, 11(6), 471; https://doi.org/10.3390/aerospace11060471 - 12 Jun 2024
Viewed by 257
Abstract
This paper identifies and classifies the essential constraints that must be addressed to allow U-space traffic autonomous guidance. Based on an extensive analysis of the state of the art in robotic guidance, physics of flight, flight safety, communication and navigation, uncrewed aircraft missions, [...] Read more.
This paper identifies and classifies the essential constraints that must be addressed to allow U-space traffic autonomous guidance. Based on an extensive analysis of the state of the art in robotic guidance, physics of flight, flight safety, communication and navigation, uncrewed aircraft missions, artificial intelligence (AI), social expectations in Europe on drones, etc., we analyzed the existing constraints and the information needs that are of essential importance to address the identified constraints. We compared the identified information needs with the last edition of the U-space Concept of Operations and identified critical gaps between the needs and proposed services. A high-level methodology to identify, measure, and close the gaps is proposed. Full article
(This article belongs to the Topic Civil and Public Domain Applications of Unmanned Aviation)
Show Figures

Figure 1

22 pages, 15122 KiB  
Article
Effects of Leading Edge Radius on Stall Characteristics of Rotor Airfoil
by Simeng Jing, Guoqing Zhao, Yuan Gao and Qijun Zhao
Aerospace 2024, 11(6), 470; https://doi.org/10.3390/aerospace11060470 - 12 Jun 2024
Viewed by 187
Abstract
The effects of leading edge radius on the static and dynamic stall characteristics of rotor airfoils are investigated. Initially, a parametric airfoil (PARFOIL) method is employed to generate four morphed airfoils with different leading edge radii based on a NACA 0012 airfoil. Subsequently, [...] Read more.
The effects of leading edge radius on the static and dynamic stall characteristics of rotor airfoils are investigated. Initially, a parametric airfoil (PARFOIL) method is employed to generate four morphed airfoils with different leading edge radii based on a NACA 0012 airfoil. Subsequently, the Reynolds-averaged Navier–Stokes (RANS) method is employed to simulate the aerodynamic characteristics of static airfoils, while the improved delayed detached-eddy simulation (IDDES) method is employed for pitching airfoils. The effectiveness and accuracy of the computational fluid dynamics (CFD) methods are demonstrated through favorable agreement between the numerical and experimental results. Finally, both the static and dynamic aerodynamic characteristics are simulated and analyzed for the airfoils with varying leading edge radii. Comparative analyses indicate that at low Mach numbers, the high adverse pressure gradient near the leading edge is the primary cause of leading edge separation and stall. A larger leading edge radius helps to reduce the suction pressure peak and adverse pressure gradients, thus delaying the leading edge separation and stall of airfoil. At high Mach numbers, the leading edge separation and stall are mainly induced by the shock wave. Variations in leading edge radius have minimal impacts on the high adverse pressure gradient induced by the shock wave, thus making the stall characteristics of airfoils almost unaffected at high Mach numbers. Full article
(This article belongs to the Special Issue Advances in Aerodynamic Shape Optimisation)
Show Figures

Figure 1

20 pages, 3720 KiB  
Article
The Possibility of Powering a Light Aircraft by Releasing the Energy Stored in Hydrogen within a Fuel Cell Stack
by John Olsen
Aerospace 2024, 11(6), 469; https://doi.org/10.3390/aerospace11060469 - 12 Jun 2024
Viewed by 267
Abstract
In this work, we examine the possibility of converting a light propeller-driven aircraft, powered by a spark-ignition, reciprocating piston, and internal combustion engine running on AVGAS, into one powered by an electric motor driven by a proton exchange membrane fuel cell stack running [...] Read more.
In this work, we examine the possibility of converting a light propeller-driven aircraft, powered by a spark-ignition, reciprocating piston, and internal combustion engine running on AVGAS, into one powered by an electric motor driven by a proton exchange membrane fuel cell stack running on hydrogen. Our studies suggest that storing hydrogen cryogenically is a better option than storing hydrogen under pressure. In comparison to cryogenic tanks, high-pressure tanks are extremely heavy and unacceptable for light aircraft. We show that the modified aircraft (including batteries) is no heavier than the original, and that the layout of the major components results in lower movement of the aircraft center-of-gravity as the aircraft consumes hydrogen. However, we acknowledge that our fuel cell aircraft cannot store the same amount of energy as the original running on AVGAS. Therefore, despite the fact that the fuel cell stack is markedly more efficient than an internal combustion engine, there is a reduction in the range of the fuel cell aircraft. One of our most important findings is that the quantity of energy that we need to dissipate to the surroundings via heat transfer is significantly greater from a fuel cell stack than from an internal combustion engine. This is particularly the case when we attempt to run the fuel cell stack at high current densities. To control this problem, our strategy during the cruise phase is to run the fuel cell stack at its maximum efficiency, where the current density is low. We size the fuel cell stack to produce at least enough power for cruise, and when we require excess power, we add the energy stored in batteries to make up the difference. Full article
(This article belongs to the Special Issue Electric Power Systems and Components for All-Electric Aircraft)
Show Figures

Figure 1

19 pages, 816 KiB  
Article
Performance and Reliability Evaluation of Innovative High-Lift Devices for Aircraft Using Electromechanical Actuators
by Carlos Cabaleiro de la Hoz, Marco Fioriti and Luca Boggero
Aerospace 2024, 11(6), 468; https://doi.org/10.3390/aerospace11060468 - 11 Jun 2024
Viewed by 225
Abstract
In the last decades, electromechanical actuators started to be introduced in transport aircraft for primary and secondary flight control surfaces. Some innovative architectures have been proposed in the literature to use these actuators for high-lift devices (flaps and slats). The state-of-the-art architecture is [...] Read more.
In the last decades, electromechanical actuators started to be introduced in transport aircraft for primary and secondary flight control surfaces. Some innovative architectures have been proposed in the literature to use these actuators for high-lift devices (flaps and slats). The state-of-the-art architecture is built with a central mechanical shaft powered by a power distribution unit connected to ballscrew actuators that actuate the flap and slat surfaces. New innovative concepts have the potential to improve the state-of-the-art architectures. However, there is a lack of quantitative results for such innovative architectures. A new methodology is proposed to preliminarily estimate performance and reliability aspects of conventional and innovative architectures. This allows quantitative comparisons to finally be obtained. The methodology is applied to a new architecture that uses electromechanical actuators for flaps and slats, providing results in terms of performance and reliability and comparing them to the current state-of-the-art high-lift devices. Results show that the new architecture is lighter than the reference one and can be more reliable. This is achieved thanks to the removal of the mechanical links among components, which allows each control surface to be deployed independently from the others. This highly increases the operational reliability of the system. Two cases are analyzed, with and without actuator jamming. This provides more realistic results since this failure mode is currently the main reason why electromechanical actuators are not being used for more applications. The innovative architecture outperforms the conventional one in the case where the electromechanical actuators are not affected by the jamming failure mode. Full article
12 pages, 1571 KiB  
Article
Airborne Lithium Battery Health Assessment: An Improved Support Vector Machine Algorithm for Imbalanced Sample Sets
by Chunxia Yang, Hongjuan Ge, Hui Jin and Shengjun Liu
Aerospace 2024, 11(6), 467; https://doi.org/10.3390/aerospace11060467 - 11 Jun 2024
Viewed by 206
Abstract
The health assessment of airborne lithium batteries is crucial for flight testing, ensuring the safety and reliability of aircraft power systems. This paper proposes a support vector machine-based algorithm for the health assessment of airborne lithium batteries, featuring a dynamic correction mechanism for [...] Read more.
The health assessment of airborne lithium batteries is crucial for flight testing, ensuring the safety and reliability of aircraft power systems. This paper proposes a support vector machine-based algorithm for the health assessment of airborne lithium batteries, featuring a dynamic correction mechanism for the risk loss penalty parameter. The proposed approach systematically adjusts risk loss penalty parameters based on sample misjudgment ratios and incorporates fault identification corrections to meet the safety requirements of the airborne operation. The experimental results demonstrate the stability and reliability of the proposed algorithm in hyperplane deviation suppression as well as significant improvements in fault sample recall rates. When compared with traditional SVM and other baseline methods such as Random Forest and SVR, our method significantly outperformed these algorithms in terms of accuracy, recall rate, and precision rate. This study provides an efficient and reliable method for the health assessment of airborne lithium batteries, with significant application value. Full article
(This article belongs to the Special Issue Recent Advances in Flight Testing)
16 pages, 481 KiB  
Article
Topology Perception and Relative Positioning of UAV Swarm Formation Based on Low-Rank Optimization
by Chengliang Di and Xiaozhou Guo
Aerospace 2024, 11(6), 466; https://doi.org/10.3390/aerospace11060466 - 11 Jun 2024
Viewed by 246
Abstract
In a satellite-denied environment, a swarm of drones is capable of achieving relative positioning and navigation by leveraging the high-precision ranging capabilities of the inter-drone data link. However, because of factors such as high drone mobility, complex and time-varying channel environments, electromagnetic interference, [...] Read more.
In a satellite-denied environment, a swarm of drones is capable of achieving relative positioning and navigation by leveraging the high-precision ranging capabilities of the inter-drone data link. However, because of factors such as high drone mobility, complex and time-varying channel environments, electromagnetic interference, and poor communication link quality, distance errors and even missing distance values between some nodes are inevitable. To address these issues, this paper proposes a low-rank optimization algorithm based on the eigenvalue scaling of the distance matrix. By gradually limiting the eigenvalues of the observed distance matrix, the algorithm reduces the rank of the matrix, bringing the observed distance matrix closer to the true value without errors or missing data. This process filters out distance errors, estimates and completes missing distance elements, and ensures high-precision calculations for subsequent topology perception and relative positioning. Simulation experiments demonstrate that the algorithm exhibits significant error filtering and missing element completion capabilities. Using the F-norm metric to measure the relative deviation from the true value, the algorithm can optimize the relative deviation of the observed distance matrix from 11.18% to 0.25%. Simultaneously, it reduces the relative positioning error from 518.05 m to 35.24 m, achieving robust topology perception and relative positioning for the drone swarm formation. Full article
(This article belongs to the Special Issue UAV System Modelling Design and Simulation)
Show Figures

Figure 1

31 pages, 25814 KiB  
Article
Experimental Pressure Gain Analysis of Pulsed Detonation Engine
by Alina Bogoi, Tudor Cuciuc, Andrei Vlad Cojocea, Mihnea Gall, Ionuț Porumbel and Constantin Eusebiu Hrițcu
Aerospace 2024, 11(6), 465; https://doi.org/10.3390/aerospace11060465 - 11 Jun 2024
Viewed by 317
Abstract
A pulsed detonation chamber (PDC) equipped with Hartmann–Sprenger resonators has been designed and tested for both Hydrogen/air and Hydrogen/Oxygen mixtures. A full-factorial experimental campaign employing four factors with four levels each has been carried out for both mixtures. Instantaneous static pressure has been [...] Read more.
A pulsed detonation chamber (PDC) equipped with Hartmann–Sprenger resonators has been designed and tested for both Hydrogen/air and Hydrogen/Oxygen mixtures. A full-factorial experimental campaign employing four factors with four levels each has been carried out for both mixtures. Instantaneous static pressure has been measured at two locations on the exhaust pipe of the PDC, and the signal has been processed to extract the average and maximum cycle pressures and the operating frequency of the spark plug. The PDC has been shown to be able to reach sustained detonation cycles over a length below 200 mm, measured from the spark plug to the first pressure sensor. The optimal regimes for both air and Oxygen operation have been determined, and the influence of the four factors on the responses is discussed. Full article
Show Figures

Figure 1

19 pages, 13878 KiB  
Article
Numerical Investigation of Model Support, Closed Engine Nacelle and Scale Effect on a Wind Tunnel Test Model
by Ioan-Laurentiu Padureanu, Dumitru Pepelea, Gilbert Stoican, Marco Marini, Nicole Viola and Matthew Clay
Aerospace 2024, 11(6), 464; https://doi.org/10.3390/aerospace11060464 - 11 Jun 2024
Viewed by 218
Abstract
In the frame of the H2020 MORE&LESS project co-funded by European Commission, a test campaign for a hypersonic vehicle demonstrator took place at the INCAS Trisonic Facility. CFD analysis was used to quantify the effects of the wind tunnel model support, the closed [...] Read more.
In the frame of the H2020 MORE&LESS project co-funded by European Commission, a test campaign for a hypersonic vehicle demonstrator took place at the INCAS Trisonic Facility. CFD analysis was used to quantify the effects of the wind tunnel model support, the closed engine nacelle, and to perform the Reynolds number extrapolation. Three sets of simulations were used in order to generate the corrections. The wind tunnel configuration with sting, sting cavity, and closed nacelle was used as the baseline, with the aim of matching the experimental results as precisely as possible. A configuration with a flow-through nacelle and the shock cone in the appropriate position for each Mach number and no sting or cavity was used to determine the effect of the sting and the closed nacelle. For the Reynolds extrapolation, a 1:1 model was used, with the boundary conditions deriving from the theoretical trajectory of the vehicle. The CFD results for the wind tunnel configuration closely align with the experimental data. Significant differences between the three configurations can be observed just for the pitching moment, and those are caused by the presence of the sting and the open nacelle. The difference in Reynolds number does not seem to have a significant effect on the aerodynamic coefficients. Full article
Show Figures

Figure 1

28 pages, 2760 KiB  
Article
An rVPM-Based Aerodynamic Hybrid Optimization Method for Coaxial Rotor with Differentiated Upper and Lower Blades in Both Hover and High-Speed Cruising States
by Zhiwei Ding, Dengyan Duan, Chaoqun Zhang and Jianbo Li
Aerospace 2024, 11(6), 463; https://doi.org/10.3390/aerospace11060463 - 9 Jun 2024
Viewed by 226
Abstract
To enhance the performance of rigid coaxial rotors across both hovering and high-speed cruising conditions, this study develops a novel aerodynamic optimization method that differentiates between the upper and lower rotors. Utilizing the lifting line and reformulated viscous vortex particle method (rVPM), this [...] Read more.
To enhance the performance of rigid coaxial rotors across both hovering and high-speed cruising conditions, this study develops a novel aerodynamic optimization method that differentiates between the upper and lower rotors. Utilizing the lifting line and reformulated viscous vortex particle method (rVPM), this approach models the complex wake fields of coaxial rotors and accurately assesses the aerodynamic loads on the blades. The optimization of geometric properties such as planform configuration and nonlinear twist is conducted through an innovative solver that integrates simulated annealing with the Nelder–Mead algorithm, ensuring both rapid and comprehensive optimization results. Comparative analyses demonstrate that these tailored geometric adjustments significantly enhance efficiency in both operational states, surpassing traditional methods. This research provides a strategic framework for addressing the varied aerodynamic challenges presented by different flight states in coaxial rotor design. Full article
(This article belongs to the Special Issue Advances in Aerodynamic Shape Optimisation)
18 pages, 22173 KiB  
Article
Structural Analysis and Testing of a Flexible Rudder Using a Cosine Honeycomb Structure
by Jinwei Huang, Weidong Liu, Yue Zhou and Dian Liu
Aerospace 2024, 11(6), 462; https://doi.org/10.3390/aerospace11060462 - 8 Jun 2024
Viewed by 273
Abstract
This paper introduces a new type of flexible rudder surface based on the cosine-type zero Poisson’s ratio honeycomb to enhance the adaptive capabilities of aircraft and enable multi-condition, rudderless flight. The zero Poisson’s ratio honeycomb structure exhibits exceptional in-plane and out-of-plane deformation capacities, [...] Read more.
This paper introduces a new type of flexible rudder surface based on the cosine-type zero Poisson’s ratio honeycomb to enhance the adaptive capabilities of aircraft and enable multi-condition, rudderless flight. The zero Poisson’s ratio honeycomb structure exhibits exceptional in-plane and out-of-plane deformation capacities, as well as a high load-bearing capability. To investigate the deformation characteristics of flexible rudder surfaces utilizing cosine honeycomb structures, this study undertakes a comprehensive investigation through finite element simulation and 3D printing experiments. Moreover, this study analyzed the impact of honeycomb parameters and layout on the deflection performance and weight. The flexible rudder surface, fabricated from nylon, achieves smooth and consistent chordwise bending deformation, as well as uniform spanwise deformation within a tolerance of ±25°, and the maximum equivalent stress observed was 31.99 MPa, which is within the material’s allowable stress limits (50 MPa). Finite element simulation results indicate that once the deflection angle of the rocker exceeds 15°, a discernible deviation arises between the actual deflection angle of the flexible control surface and that of the rocker. Furthermore, this deviation escalates with increasing rocker rotation angles, and this discrepancy can be mitigated by augmenting the number of cosine honeycomb cells within the flexible rudder surface. Finally, a prototype of the flexible rudder surface was successfully produced using 3D printing technology, and the experimental results confirmed the deformation behavior, aligning with simulation outcomes with a deviation of less than 20%. These findings confirm the effective deflection performance of the designed flexible rudder surface, highlighting its potential application in small unmanned aerial vehicles. Full article
Show Figures

Figure 1

26 pages, 1684 KiB  
Article
An Adaptive Similar Scenario Matching Method for Predicting Aircraft Taxiing Time
by Peiran Qiao, Minghua Hu, Jianan Yin, Jiaming Su, Yutong Chen and Mengxuan Yin
Aerospace 2024, 11(6), 461; https://doi.org/10.3390/aerospace11060461 - 7 Jun 2024
Viewed by 239
Abstract
Accurate prediction of taxiing time is important in ensuring efficient and safe operations on the airport surface. It helps improve ground operation efficiency, reduce fuel waste, and improve carbon emissions at the airport. In actual operations, taxiing time is influenced by various factors, [...] Read more.
Accurate prediction of taxiing time is important in ensuring efficient and safe operations on the airport surface. It helps improve ground operation efficiency, reduce fuel waste, and improve carbon emissions at the airport. In actual operations, taxiing time is influenced by various factors, including a large number of categorical features. However, few previous studies have focused on selecting such features. Additionally, traditional taxiing time prediction methods are often black-box models that only provide a single prediction result; they fail to provide effective practical references for controllers. Therefore, this paper analyses the features that affect taxiing time from different data types and forms a taxi feature set consisting of nine key features. We also propose a taxiing time prediction method based on adaptive scenario matching rules. This process classifies the scenarios into multiple typical historical scenario sets and adaptively matches the current target scenario to a typical scenario set based on quantified rules. Then, based on the matching results, a pre-trained model obtained from the corresponding scenario set is used to predict the taxiing time of an aircraft in the target scenario, aiming to mitigate the impact of data heterogeneity on prediction results. Experimental results show that compared to baseline methods, the mean absolute error and root mean square error of the proposed method decreased by 4.8% and 12.6%, respectively. This method significantly reduces the fluctuations in results caused by sample heterogeneity and enhances controllers’ acceptance of prediction results from the model. It can be used to further improve auxiliary decision making systems and enhance the precise control capabilities of airport surface operations. Full article
(This article belongs to the Section Air Traffic and Transportation)
20 pages, 5794 KiB  
Article
Optimal Impulsive Orbit Transfers from Gateway to Low Lunar Orbit
by Dario Sanna, Edoardo Maria Leonardi, Giulio De Angelis and Mauro Pontani
Aerospace 2024, 11(6), 460; https://doi.org/10.3390/aerospace11060460 - 7 Jun 2024
Viewed by 327
Abstract
Gateway represents a key element of the Artemis program for the upcoming lunar exploration aimed at establishing a sustainable presence by the mid-2030s. This paper investigates minimum-fuel bi-impulsive orbit transfers from Gateway to low lunar orbits (LLOs) with a maximum time of flight [...] Read more.
Gateway represents a key element of the Artemis program for the upcoming lunar exploration aimed at establishing a sustainable presence by the mid-2030s. This paper investigates minimum-fuel bi-impulsive orbit transfers from Gateway to low lunar orbits (LLOs) with a maximum time of flight of 48 h. Two distinct scenarios are analyzed: (i) target orbits with free right ascension of the ascending node (RAAN), and (ii) target orbits with specified RAAN. For case (i), a global optimization technique based on a heuristic algorithm is exploited to obtain the minimum-fuel transfer. Several inclinations of the target orbit are considered. For case (ii), two distinct techniques are proposed: (a) a purely heuristic approach, and (b) a semi-analytical method based on local refinement of a Lambert-based solution. Numerical propagations are conducted in all scenarios in a high-fidelity framework that includes all relevant perturbations. A comparison between the different strategies and the related numerical results is provided. Full article
(This article belongs to the Special Issue Spacecraft Orbit Transfers)
Show Figures

Figure 1

27 pages, 3218 KiB  
Article
An Information Integration Technology for Safety Assessment on Civil Airborne System
by Xi Chen, Quan Zou, Jie Bai and Lei Dong
Aerospace 2024, 11(6), 459; https://doi.org/10.3390/aerospace11060459 - 6 Jun 2024
Viewed by 268
Abstract
With the significant expansion of civil aviation, particularly in the low-altitude economy, there is a significant gap between the escalating demand for airworthiness certification of novel aircraft designs, such as electric vertical take-off and landing (eVTOL) vehicles, and the inefficiency of the current [...] Read more.
With the significant expansion of civil aviation, particularly in the low-altitude economy, there is a significant gap between the escalating demand for airworthiness certification of novel aircraft designs, such as electric vertical take-off and landing (eVTOL) vehicles, and the inefficiency of the current safety assessment process. This gap is partially attributed to safety assessors’ limited exposure to these innovative aircraft models in the safety assessment process, necessitating extensive efforts in identifying precedents and their handling strategies. Complicating matters further, pertinent case studies are scattered across diverse, unstandardized digital formats, obliging assessors to navigate voluminous electronic records while concurrently establishing links among fragmented information scattered across multiple files. This study introduces an advanced information integration methodology, comprising a multi-level path-based architecture and a self-updating algorithm. The proposed method not only furnishes safety assessors with pertinent knowledge featuring explicative interconnectedness automatically, but also dynamically enriches this knowledge corpus through operational usage. Additionally, we devise a suite of evaluative criteria to validate the capacity of our method in processing and consolidating relevant safety datasets. Experimental analyses affirm the efficacy of our proposed approach in streamlining and refreshing safety assessment data. The automation of the retrieval of analogous cases, which relieves the reliance on expert knowledge, enhances the efficiency of the overall safety appraisal procedure. Consequently, this research contributes a solution to enhancing the velocity and accuracy of aircraft certification processes. Full article
(This article belongs to the Special Issue Recent Advances in Flight Testing)
Show Figures

Figure 1

34 pages, 13798 KiB  
Article
Ice Object Exclusion Characteristics of Turboshaft Engine Inlet under Helicopter/Inlet Integration Conditions
by Ge Zhou, Haoyu Zhou, Zhenlong Wu, Huijun Tan and Wanglong Qin
Aerospace 2024, 11(6), 458; https://doi.org/10.3390/aerospace11060458 - 5 Jun 2024
Viewed by 290
Abstract
In this study, the influence laws of different parameters on the exclusion characteristics of hailstone and ice flake, and on the aerodynamic performance of the inlet are studied by numerical method. The motion of the hailstone and ice flake is simulated using the [...] Read more.
In this study, the influence laws of different parameters on the exclusion characteristics of hailstone and ice flake, and on the aerodynamic performance of the inlet are studied by numerical method. The motion of the hailstone and ice flake is simulated using the 6-DOF method. Results show that the inhalation of hailstone in the inlet decreases total pressure distortion by about 20%, and the total pressure recovery coefficient is essentially unchanged. Icing of the upper lip decreases the total pressure distortion of the inlet by about 22%, and the total pressure recovery coefficient decreases by 0.6%. The ice flakes on the inner and outer lip, when shed and brake by collision with the center body, will cause damage to the engine duct. The shedding and breaking of ice flake at an angle of 150° to the lip can result in a large amount of ice flake debris entering the engine duct, threatening the performance and structure of the engine in the rear. The motion characteristics of hailstone and ice flake under helicopter fuselage/rotor/inlet integration conditions are revealed. It also provides a reference on the numerical methods for the numerical study of hailstone/ice flake exclusion characteristics of helicopter fuselage/rotor/inlet integration conditions. Full article
Show Figures

Figure 1

15 pages, 4168 KiB  
Article
Robust Optimization Model of Airport Group Coordinated Timetable with Uncertain Flight Time
by Jianzhong Yan and Minghua Hu
Aerospace 2024, 11(6), 457; https://doi.org/10.3390/aerospace11060457 - 5 Jun 2024
Viewed by 233
Abstract
This study develops a robust 0–1 linear optimization programming model for airport group timetable coordination, aiming at assigning each flight at an airport to a unique time slot to avoid conflicts between multiple flights from different airports at the same shared waypoint in [...] Read more.
This study develops a robust 0–1 linear optimization programming model for airport group timetable coordination, aiming at assigning each flight at an airport to a unique time slot to avoid conflicts between multiple flights from different airports at the same shared waypoint in an uncertain environment. Flight times between airports and shared waypoints are assumed to have an arbitrary distribution in the interval. Furthermore, some practical constraints, such as the time-varying capacity of each airport, waypoints affected by factors such as weather and traffic control, and maximum delay times for each flight, are considered in this study. The objective is to minimize the total delay time for all flights. The solution is obtained using the RSOME solver. Finally, a real-world case of the Beijing–Tianjin–Hebei airport group, China, is used to optimize the schedules of four airports to prove the accuracy and effectiveness of the method developed in this study. The influence of the budget of uncertainty parameters on model performance is also analyzed. Full article
Show Figures

Figure 1

55 pages, 29220 KiB  
Article
Vision System for the Mars Sample Return Capture Containment and Return System (CCRS)
by Brent J. Bos, David L. Donovan, John I. Capone, Chen Wang, Terra C. Hardwick, Dylan E. Bell, Yuqing Zhu, Robert Podgurski, Bashar Rizk, Ireneusz Orlowski, Rachel A. Edison, David A. Harvey, Brianna Dizon, Lindsay Haseltine, Kristoffer C. Olsen, Chad Sheng, Robert R. Bousquet, Luan Q. Vo, Georgi T. Georgiev, Kristen A. Washington, Michael J. Singer, Stefan Ioana, Anloc H. Le, Elena M. Georgieva, Michael T. Hackett, Michael A. Ravine, Michael Caplinger, Phillip Coulter, Erin Percy, Charles Torisky, Jean-Marie Lauenstein, Kaitlyn L. Ryder, Michael J. Campola, Dillon E. Johnstone, William J. Thomes, Richard G. Schnurr, John C. McCloskey, Eugenia L. De Marco, Ellen Lee, Calinda M. Yew, Bo Yang, Mingyu Han and Bartosz Blonskiadd Show full author list remove Hide full author list
Aerospace 2024, 11(6), 456; https://doi.org/10.3390/aerospace11060456 - 5 Jun 2024
Viewed by 325
Abstract
The successful 2020 launch and 2021 landing of the National Aeronautics and Space Administration’s (NASA) Perseverance Mars rover initiated the first phase of the NASA and European Space Agency (ESA) Mars Sample Return (MSR) campaign. The goal of the MSR campaign is to [...] Read more.
The successful 2020 launch and 2021 landing of the National Aeronautics and Space Administration’s (NASA) Perseverance Mars rover initiated the first phase of the NASA and European Space Agency (ESA) Mars Sample Return (MSR) campaign. The goal of the MSR campaign is to collect scientifically interesting samples from the Martian surface and return them to Earth for further study in terrestrial laboratories. The MSR campaign consists of three major spacecraft components to accomplish this objective: the Perseverance Mars rover, the Sample Retrieval Lander (SRL) and the Earth Return Orbiter (ERO). Onboard the ERO spacecraft is the Capture, Containment and Return System (CCRS). CCRS will capture, process and return to Earth the samples that have been collected after they are launched into Mars orbit by the Mars Ascent Vehicle (MAV), which is delivered to Mars onboard the SRL. To facilitate the processing of the orbiting sample (OS) via the CCRS, we have designed and developed a vision system to determine the OS capture orientation. The vision system is composed of two cameras sensitive to the visible portion of the electromagnetic spectrum and two illumination modules constructed from broadband light emitting diodes (LED). Vision system laboratory tests and physics-based optical simulations predict CCRS ground processing will be able to correctly identify the OS post-capture orientation using only a single vision system image that is transmitted to Earth from Mars orbit. Full article
(This article belongs to the Special Issue Spacecraft Sample Collection)
Show Figures

Figure 1

24 pages, 10276 KiB  
Article
Detection of Precursors of Thermoacoustic Instability in a Swirled Combustor Using Chaotic Analysis and Deep Learning Models
by Boqi Xu, Zhiyu Wang, Hongwu Zhou, Wei Cao, Zhan Zhong, Weidong Huang and Wansheng Nie
Aerospace 2024, 11(6), 455; https://doi.org/10.3390/aerospace11060455 - 5 Jun 2024
Viewed by 292
Abstract
This paper investigates the role of chaotic analysis and deep learning models in combustion instability predictions. To detect the precursors of impending thermoacoustic instability (TAI) in a swirled combustor with various fuel injection strategies, a data-driven framework is proposed in this study. Based [...] Read more.
This paper investigates the role of chaotic analysis and deep learning models in combustion instability predictions. To detect the precursors of impending thermoacoustic instability (TAI) in a swirled combustor with various fuel injection strategies, a data-driven framework is proposed in this study. Based on chaotic analysis, a recurrence matrix derived from combustion system is used in deep learning models, which are able to detect precursors of TAI. More specifically, the ResNet-18 network model is trained to predict the proximity of unstable operation conditions when the combustion system is still stable. The proposed framework achieved state-of-the-art 91.06% accuracy in prediction performance. The framework has potential for practical applications to avoid an unstable operation domain in active combustion control systems and, thus, can offer on-line information on the margin of the combustion instability. Full article
(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)
Show Figures

Figure 1

1 pages, 131 KiB  
Retraction
RETRACTED: Eapen et al. A 6U CubeSat Platform for Low Earth Remote Sensing: DEWASAT-2 Mission Concept and Analysis. Aerospace 2023, 10, 815
by Ann Mary Eapen, Sidi Ahmed Bendoukha, Reem Al-Ali and Abdulrahman Sulaiman
Aerospace 2024, 11(6), 454; https://doi.org/10.3390/aerospace11060454 - 5 Jun 2024
Viewed by 181
Abstract
The Aerospace Editorial Office retracts and removes the article entitled “Eapen et al [...] Full article
16 pages, 12942 KiB  
Article
Data Reduction Technologies in Prediction of Propeller Noise
by Samuel Afari and Reda Mankbadi
Aerospace 2024, 11(6), 453; https://doi.org/10.3390/aerospace11060453 - 4 Jun 2024
Viewed by 272
Abstract
High-fidelity computations are often used in predicting the tonal and broadband noise of propellers and rotors associated with Advanced Air Mobility Vehicles (AAMVs). But LES is both CPU and storage intensive. We present here an investigation of the feasibility of reduction methods such [...] Read more.
High-fidelity computations are often used in predicting the tonal and broadband noise of propellers and rotors associated with Advanced Air Mobility Vehicles (AAMVs). But LES is both CPU and storage intensive. We present here an investigation of the feasibility of reduction methods such as Proper Orthogonal Decomposition as well as Dynamic Mode Decomposition for reduction of data obtained via LES to be used further to obtain additional parameters. Specifically, we investigate how accurate reduced models of the high-fidelity computations can be used to predict the far-field noise. It is found that POD is capable of accurately reconstructing the parameters of interest with 15–40% of the total mode energies, whereas the DMD can only reconstruct primitive parameters such as velocity and pressure loosely. A rank truncation convergence criterion > 99.8% is needed for better performance of the DMD algorithm. In the far-field spectra, DMD can only predict the tonal contents in the lower and mid frequencies, while the POD can reproduce all frequencies of interest. Full article
(This article belongs to the Section Aeronautics)
Show Figures

Figure 1

25 pages, 8722 KiB  
Article
Study on the Influence of a Powered Nacelle on the Wake Vortex Characteristics of Wide-Body Aircraft
by Hexiang Wang, Junqiang Wu, Qiuting Guo, Guangyuan Liu, Jifei Wu, Dawei Liu, Yang Tao and Neng Xiong
Aerospace 2024, 11(6), 452; https://doi.org/10.3390/aerospace11060452 - 4 Jun 2024
Viewed by 250
Abstract
The aircraft wake vortex is an important factor affecting flight safety; as an important part of the aircraft, the powered nacelle will inevitably have an important impact on the aircraft wake vortex, so it is of great practical significance to research it. The [...] Read more.
The aircraft wake vortex is an important factor affecting flight safety; as an important part of the aircraft, the powered nacelle will inevitably have an important impact on the aircraft wake vortex, so it is of great practical significance to research it. The present study focused on the numerical simulation of the wake flow of large aircraft (as the front aircraft) and the comparative analysis of the influence of engine jets on the wake flow. In order to meet the accuracy requirements and control the consumption of computing resources, LES and RANS methods were compared, and the RANS method was finally selected for subsequent calculation. The dynamic effect of jet flow was simulated by simplifying the boundary conditions of the inlet fan and outlet bypass as the mass flow boundary condition. The simulation results showed that the engine nacelle will have a significant impact on the morphology of the aircraft wake flow (position and strength of the main vortex in the wake flow system), which is caused by the vortices formed under the shear flow and separated flow of the nacelle. However, the nacelle will not significantly change the total strength of the wake vortex (half-plane circulation). The engine jet intensity causes additional turbulent mixing, which will accelerate the fusion of the nacelle vortex and ultimately change the intensity ratio of the inner wing vortex and the wingtip vortex, affecting the trajectory of the wake of the mean vortex. The study provides a corresponding reference for the following research on a wake vortex by a powered nacelle. Full article
Show Figures

Figure 1

25 pages, 2097 KiB  
Article
Operational Angular Track Reconstruction in Space Surveillance Radars through an Adaptive Beamforming Approach
by Marco Felice Montaruli, Maria Alessandra De Luca, Mauro Massari, Germano Bianchi and Alessio Magro
Aerospace 2024, 11(6), 451; https://doi.org/10.3390/aerospace11060451 - 1 Jun 2024
Viewed by 514
Abstract
In the last few years, many space surveillance initiatives have started to consider the problem represented by resident space object overpopulation. In particular, the European Space Surveillance and Tracking (EUSST) consortium is in charge of providing services like collision avoidance, fragmentation analysis, and [...] Read more.
In the last few years, many space surveillance initiatives have started to consider the problem represented by resident space object overpopulation. In particular, the European Space Surveillance and Tracking (EUSST) consortium is in charge of providing services like collision avoidance, fragmentation analysis, and re-entry, which rely on measurements obtained through ground-based sensors. BIRALES is an Italian survey radar belonging to the EUSST framework and is capable of providing measurements including Doppler shift, slant range, and angular profile. In recent years, the Music Approach for Track Estimate and Refinement (MATER) algorithm has been developed to retrieve angular tracks through an adaptive beamforming technique, guaranteeing the generation of more accurate and robust measurements with respect to the previous static beamforming approach. This work presents the design of a new data processing chain to be used by BIRALES to compute the angular track. The signal acquired by the BIRALES receiver array is down-converted and the receiver bandwidth is split into multiple channels, in order to maximize the signal-to-noise ratio of the measurements. Then, the signal passes through a detection block, where an isolation procedure creates, for each epoch, signal correlation matrices (CMs) related to the channels involved in the detection and then processes them to isolate the data stream related to a single detected source. Consequently, for each epoch and for each detected source, just the CM featuring the largest signal contribution is kept, allowing deriving the Doppler shift measurement from the channel illumination sequence. The MATER algorithm is applied to each CM stream, first estimating the signal directions of arrival, then grouping them in the observation time window, and eventually returning the target angular track. Ambiguous estimates may be present due to the configuration of the receiver array, which cause spatial aliasing phenomena. This problem can be addressed by either exploiting transit prediction (in the case of cataloged objects), or by applying tailored criteria (for uncatalogued objects). The performance of the new architecture was assessed in real operational scenarios, demonstrating the enhancement represented by the implementation of the channelization strategy, as well as the angular measurement accuracy returned by MATER, in both nominal and off-nominal scenarios. Full article
(This article belongs to the Special Issue Track Detection of Resident Space Objects)
13 pages, 3321 KiB  
Article
Pilot Assistance Systems for Energy-Optimized Approaches: Is It Possible to Reduce Fuel Consumption and Noise at the Same Time?
by Jean Marc Wunderli, Jonas Meister, Johan Boyer, Martin Gerber, Tobias Bauer and Fethi Abdelmoula
Aerospace 2024, 11(6), 450; https://doi.org/10.3390/aerospace11060450 - 1 Jun 2024
Viewed by 241
Abstract
Air traffic has appreciable environmental impacts, especially regarding gaseous emissions and noise. Recent studies have shown that the energy management during approach is a driving factor regarding environmental impact and is especially challenging for pilots. In a previous project, a newly developed pilot [...] Read more.
Air traffic has appreciable environmental impacts, especially regarding gaseous emissions and noise. Recent studies have shown that the energy management during approach is a driving factor regarding environmental impact and is especially challenging for pilots. In a previous project, a newly developed pilot assistance system called LNAS (Low Noise Augmentation System) showed the potential of energy-optimized approaches to reduce fuel consumption and noise. Within the SESAR Exploratory Research project DYNCAT, novel functions based on LNAS have been integrated in the flight management system. In this contribution, results from real-time simulations with the enhanced FMS are presented, and mitigation of the environmental impact is analyzed. It was shown that with DYNCAT, the energy management could be improved, resulting in a later configuration and engines mostly in idle. With DYNCAT, procedures were also flown more uniformly and the variability in noise and fuel outcomes was reduced. However, the results revealed a trade-off for optimizing noise and fuel consumption simultaneously, whereby both parameters can be improved along specific optimum curves. A perfect strategy to minimize noise would be to first reduce speed and only secondly height, as high speeds lead to higher levels of airframe noise and sound exposure increases with decreasing distance. In contrast, saving fuel might be achieved by reducing the flight time, as the engines consume fuel even when being in idle. Full article
19 pages, 15064 KiB  
Article
Exploring the Aerodynamic Effect of Blade Gap Size via a Transient Simulation of a Four-Stage Turbine
by Xinlei Hu, Le Cai, Yingjie Chen, Xuejian Li, Songtao Wang, Xinglong Fang and Kanxian Fang
Aerospace 2024, 11(6), 449; https://doi.org/10.3390/aerospace11060449 - 1 Jun 2024
Viewed by 215
Abstract
With the impact of size on low-pressure turbines (LPTs) increasing, the gap between the blades has shrunk, inevitably influencing the unsteady effects inside the turbine. In this study, the aerodynamic effect of the blade gap size is investigated using a compressible unsteady Reynolds-averaged [...] Read more.
With the impact of size on low-pressure turbines (LPTs) increasing, the gap between the blades has shrunk, inevitably influencing the unsteady effects inside the turbine. In this study, the aerodynamic effect of the blade gap size is investigated using a compressible unsteady Reynolds-averaged Navier–Stokes (URANS) model on the basis of a four-stage LPT. Simulations are conducted in which the gap between the third-stage stator (S3) and rotor (R3) varies from 0.2 to 0.8 times the axial chord length of the R3 blade. The multi-stage environment reflects the complexity of real low-Reynolds flow fields. Computational fluid dynamics is used to analyze the flow field in detail. The results demonstrate that in the small-gap (AG-0.2) case, the turbulence kinetic energy (TKE) level of the S3 wake close to the R3 leading edge is four-thirds of that in the large-gap (AG-0.8) case. The higher intensity of the wake impacting on the blade results in a higher inverse pressure gradient in the rear part of the R3 suction surface, which increases the profile loss. However, the AG-0.2 case leads to fewer losses caused by the passage vortex in the hub area under the influence of the higher intensity of the wake. Full article
Show Figures

Figure 1

20 pages, 2475 KiB  
Article
Multi-Fidelity Adaptive Sampling for Surrogate-Based Optimization and Uncertainty Quantification
by Andrea Garbo, Jigar Parekh, Tilo Rischmann and Philipp Bekemeyer
Aerospace 2024, 11(6), 448; https://doi.org/10.3390/aerospace11060448 - 31 May 2024
Viewed by 244
Abstract
Surrogate-based algorithms are indispensable in the aerospace engineering field for reducing the computational cost of optimization and uncertainty quantification analyses, particularly those involving computationally intensive solvers. This paper presents a novel approach for enhancing the efficiency of surrogate-based algorithms through a new multi-fidelity [...] Read more.
Surrogate-based algorithms are indispensable in the aerospace engineering field for reducing the computational cost of optimization and uncertainty quantification analyses, particularly those involving computationally intensive solvers. This paper presents a novel approach for enhancing the efficiency of surrogate-based algorithms through a new multi-fidelity sampling technique. Unlike existing multi-fidelity methods which are based on a single multiplicative acquisition function, the proposed technique decouples the identification of the new infill sample from the selection of the fidelity level. The location of the infill sample is determined by leveraging the highest fidelity surrogate model, while the fidelity level used for its performance evaluation is chosen as the cheapest one within the “accurate enough” models at the infill location. Moreover, the methodology introduces the application of the Jensen–Shannon divergence to quantify the accuracy of the different fidelity levels. Overall, the resulting technique eliminates some of the drawbacks of existing multiplicative acquisition functions such as the risk of continuous sampling from lower and cheaper fidelity levels. Experimental validation conducted in surrogate-based optimization and uncertainty quantification scenarios demonstrates the efficacy of the proposed approach. In an aerodynamic shape optimization task focused on maximizing the lift-to-drag ratio, the multi-fidelity strategy achieved comparable results to standard single-fidelity sampling but with approximately a five-fold improvement in computational efficiency. Likewise, a similar reduction in computational costs was observed in the uncertainty quantification problem, with the resulting statistical values aligning closely with those obtained using traditional single-fidelity sampling. Full article
(This article belongs to the Special Issue Data-Driven Aerodynamic Modeling)
Show Figures

Figure 1

24 pages, 58272 KiB  
Article
Built On-Orbit Robotically Assembled Gigatruss (BORG): Ground Robotic Demonstration
by Samantha Chapin, Holly Everson, William Chapin and Erik Komendera
Aerospace 2024, 11(6), 447; https://doi.org/10.3390/aerospace11060447 - 31 May 2024
Viewed by 234
Abstract
The next generation of large space infrastructure will require crucial advancements in current technology. Current methodologies focus on large deployable structures folded into cramped payload fairings or revolutionary assembly techniques requiring many moving components. Utilizing both in-space assembly and deployable concepts, a hybrid [...] Read more.
The next generation of large space infrastructure will require crucial advancements in current technology. Current methodologies focus on large deployable structures folded into cramped payload fairings or revolutionary assembly techniques requiring many moving components. Utilizing both in-space assembly and deployable concepts, a hybrid mixed assembly scheme was posed using smaller deployable units interspersed with rigid connecting elements to assemble these large architectures. The Built On-Orbit Robotically Assembled Gigatruss (BORG) structure allows for modularity in assembly and repair with the number of separate elements comprising the structure to be reduced, compared to strut-by-strut assembly. The following documents the process of constructing and running physical trials on a prototype BORG architecture. Additionally, a Semantic and Fiducial Aided Graph Simultaneous Localization and Mapping (SF-GraphSLAM) approach is taken to verify the relation of assembled and deployed truss elements to aid in error evaluation and state estimation. This technology demonstration stands as a proof of concept in verifying the viability of the BORG architecture as a method for large structure assembly. Full article
(This article belongs to the Special Issue Advanced Spacecraft/Satellite Technologies)
Show Figures

Figure 1

18 pages, 2890 KiB  
Article
The Derivation of an Empirical Model to Estimate the Power Spectral Density of Turbulent Boundary Layer Wall Pressure in Aircraft Using Machine Learning Regression Techniques
by Zachary Huffman and Joana Rocha
Aerospace 2024, 11(6), 446; https://doi.org/10.3390/aerospace11060446 - 31 May 2024
Viewed by 202
Abstract
Aircraft cabin noise poses a health risk for regular passengers and crew, being connected to a heightened risk of cardiovascular disease, hearing loss, and sleep deprivation. At cruise conditions, its most significant cause is random pressure fluctuations in the turbulent boundary layer of [...] Read more.
Aircraft cabin noise poses a health risk for regular passengers and crew, being connected to a heightened risk of cardiovascular disease, hearing loss, and sleep deprivation. At cruise conditions, its most significant cause is random pressure fluctuations in the turbulent boundary layer of aircraft, and as such the derivation of an accurate model to predict the power spectral density of these fluctuations remains an important ongoing research topic. Early models (such as those by Lowson and Robertson) were derived by simplifying the governing equations, the Reynolds-averaged Navier Stokes equations, and solving for fluctuating pressure. Most subsequent equations were derived either by applying statistical and mathematical techniques to simplify the Robertson and Lowson models or by making modifications to address apparent shortcomings. Overall, these models have had varying success—most are accurate near the Mach and Reynolds numbers they were designed for, but less accurate under other conditions. In response to this shortcoming, Dominique demonstrated that a novel technique (machine learning, specifically artificial neural networking) could produce a model that is accurate under most flight conditions. This paper extends this research further by applying a different machine learning technique (nonlinear least squares regression analysis) and dimensional analysis to produce a new model. The resulting equation proved accurate under its design conditions of low airspeed (approximately 11 m/s) and low turbulent Reynolds number (approximately 850,000). However, a larger dataset with more diverse flight conditions would be required to make the model more generally applicable. Full article
(This article belongs to the Topic Advances in Underwater Acoustics and Aeroacoustics)
Show Figures

Figure 1

12 pages, 2555 KiB  
Article
Identification and Analysis of Flight Delay Based on Process Relevance
by Qingmiao Ding, Linyan Ma, Yanyu Cui, Bin Cheng and Xuan He
Aerospace 2024, 11(6), 445; https://doi.org/10.3390/aerospace11060445 - 31 May 2024
Viewed by 193
Abstract
Flight delay identification is an important way to coordinate the operation time of airport ground service providers and improve the efficiency of airport operations. By analyzing the flight turnaround operation process, considering the randomness and synchronization of the turnaround process, and using Colored [...] Read more.
Flight delay identification is an important way to coordinate the operation time of airport ground service providers and improve the efficiency of airport operations. By analyzing the flight turnaround operation process, considering the randomness and synchronization of the turnaround process, and using Colored Petri Nets and Python (4.0.1), we explore the correlation between various links in the flight turnaround process and the take-off delay at the next station. This paper is committed to improving the service performance of airports and airlines, dynamically predicting flight delays, and providing guidance for avoiding excessive time in the actual operation of bad combinations. The results show that there are six kinds of bad combinations in the departure slip-out link, which is the most likely to affect the transit time. The maximum lifting degree in the bad combination is 2.043, and the maximum average delay time in the bad combination is 22.5 min. When the combination of passenger boarding and departure slip-out time is too long, it has a great positive correlation with delay. When the other links are in a state of being able to pass the station on time, the departure time and baggage loading and unloading are the two links that most affect the flight delay value. Full article
Show Figures

Figure 1

14 pages, 910 KiB  
Article
Negative Medium-Voltage Direct Current Discharges in Air under Simulated Sub-Atmospheric Pressures for All-Electric Aircraft
by Sai Pavan Kalakonda, Mohammad Hamidieh, Adil Bhojwani and Mona Ghassemi
Aerospace 2024, 11(6), 444; https://doi.org/10.3390/aerospace11060444 - 30 May 2024
Viewed by 172
Abstract
The increase in the global temperature due to greenhouse gas emissions is a major concern to the world. To achieve the goal of zero emissions by 2050 in the USA the practical realization of all-electric vehicles, particularly all-electric aircraft (AEA), is important. For [...] Read more.
The increase in the global temperature due to greenhouse gas emissions is a major concern to the world. To achieve the goal of zero emissions by 2050 in the USA the practical realization of all-electric vehicles, particularly all-electric aircraft (AEA), is important. For the design of electrical power systems (EPSs) in all-electric aircraft, a bipolar medium-voltage direct current (MVDC) system of ±5 kV is being investigated. However, several challenges manifest when using such voltages in a low-pressure environment. One of the main challenges is the partial discharge (PD) behavior of the insulation. It is important to study the PD behavior of the insulation by simulating the aviation environment in the lab. This work aimed to study the partial discharge behavior of air under a negative DC voltage in a needle-to-plane electrode geometry by simulating the aviation pressures in the lab. The partial discharge inception voltage (PDIV) and the breakdown voltage (BDV) show an obvious pressure-dependent variation. Regression analysis was performed to better understand the relationship between the PDIV and pressures. Plots were drawn for the average discharge current at each voltage step until breakdown. This paper’s findings can provide valuable insight into the design of EPS for an AEA. To the best of our knowledge, such a study has not been carried out to date. Full article
(This article belongs to the Special Issue Electric Power Systems and Components for All-Electric Aircraft)
Previous Issue
Back to TopTop