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Aerospace, Volume 10, Issue 3 (March 2023) – 118 articles

Cover Story (view full-size image): This research proposes the mission performance analysis of regional hybrid electric aircraft using mission simulation tools specifically developed for this novel aircraft. The analysis focuses on both the design point and off-design missions, examining the entire operating envelope; the payload-range diagram is utilized to effectively assess the operating performance. The trade-off in the power supply split strategies between the electrical and thermal sources is described in detail, focusing on fuel consumption and maximum flight distance. The results indicate that integrating hybrid electric propulsion on regional aircraft can offer benefits in terms of both environmental performance, with reductions in direct fuel consumption, and operational performance, including significant extension of the operating envelope. View this paper
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15 pages, 5158 KiB  
Article
Design and Development of Medium Energy Proton Detector Onboard FY-3E Satellite
by Huanxin Zhang, Xiaoxin Zhang, Jinhua Wang, Cong Huang, Jiawei Li, Weiguo Zong, Guohong Shen, Shenyi Zhang, Yong Yang and Pengfei Zhang
Aerospace 2023, 10(3), 321; https://doi.org/10.3390/aerospace10030321 - 22 Mar 2023
Cited by 2 | Viewed by 1300
Abstract
This article introduces the instrument design of the medium energy proton detector (energy range: 30 keV–5 MeV) mounted on the FY-3E satellite. Through the design and optimization of the sensor signal processing circuit, the anti-electromagnetic interference ability of the medium energy particle detector [...] Read more.
This article introduces the instrument design of the medium energy proton detector (energy range: 30 keV–5 MeV) mounted on the FY-3E satellite. Through the design and optimization of the sensor signal processing circuit, the anti-electromagnetic interference ability of the medium energy particle detector is greatly enhanced. The designed aluminum plating on sensors can effectively exclude the light pollution to the medium energy protons. The designed permanent annular magnet has a deflection efficiency of more than 95% for medium energy electrons below 1.0 MeV. Additionally, by designing the logical working mode of the sensor, the contamination by other high energy particles (high energy electrons > 1.5 MeV, high energy protons > 5 MeV, and heavy ions) is excluded. Combining the above methods, the detector achieves the detection lower limit of 30 keV for medium energy protons. Its energy resolution is better than 15%@100 keV and the mixing ratio of electrons is less than 2%. Full article
(This article belongs to the Special Issue Meteorological Satellites Data Analysis)
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14 pages, 2375 KiB  
Article
Analyzing the Effect of Dynamic Pressure Drop on Corona Discharges for Aircraft Applications
by Pau Bas-Calopa, Jordi-Roger Riba and Manuel Moreno-Eguilaz
Aerospace 2023, 10(3), 320; https://doi.org/10.3390/aerospace10030320 - 22 Mar 2023
Viewed by 1365
Abstract
The combination of the low-pressure environment found in aircraft systems and the gradual electrification of aircraft increases the risk of electrical discharges occurrence. This is an undesirable situation that compromises aircraft safety and complicates maintenance operations. Experimental data are needed to understand this [...] Read more.
The combination of the low-pressure environment found in aircraft systems and the gradual electrification of aircraft increases the risk of electrical discharges occurrence. This is an undesirable situation that compromises aircraft safety and complicates maintenance operations. Experimental data are needed to understand this problem. However, most of the published studies are based on static pressure conditions, but aircraft systems are exposed to dynamic pressure conditions, especially during the climb and descent phases of flight. This paper analyzes the effect of dynamic pressure during the climb phase on the corona inception voltage because this phase experiences the worst pressure drop rate. The experimental evidence presented in this paper shows that within the analyzed pressure drop rate range, the dynamic pressure conditions do not have a significant effect on the corona inception value under typical conditions found in aircraft systems during the climb phase. Full article
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30 pages, 2204 KiB  
Article
Comprehensive Comparison of Different Integrated Thermal Protection Systems with Ablative Materials for Load-Bearing Components of Reusable Launch Vehicles
by Stefano Piacquadio, Dominik Pridöhl, Nils Henkel, Rasmus Bergström, Alessandro Zamprotta, Athanasios Dafnis and Kai-Uwe Schröder
Aerospace 2023, 10(3), 319; https://doi.org/10.3390/aerospace10030319 - 22 Mar 2023
Cited by 2 | Viewed by 2300
Abstract
Economic viability of small launch vehicles, i.e., microlaunchers, is impaired by several factors, one of which is a higher dry to wet mass ratio as compared to conventional size launchers. Although reusability may reduce launch cost, it can drive dry and/or wet mass [...] Read more.
Economic viability of small launch vehicles, i.e., microlaunchers, is impaired by several factors, one of which is a higher dry to wet mass ratio as compared to conventional size launchers. Although reusability may reduce launch cost, it can drive dry and/or wet mass to unfeasibly high levels. In particular, for load-bearing components that are exposed to convective heating during the aerothermodynamic phase of the re-entry, the mass increase due to the presence of a thermal protection system (TPS) must be considered. Examples of such components are aerodynamic drag devices (ADDs), which are extended during the re-entry. These should withstand high mechanical loading, be thermally protected to avoid failure, and be reusable. Ablative materials can offer lightweight thermal protection, but they represent an add-on mass for the structure and they are rarely reusable. Similarly, TPS based on ceramic matrix composite (CMC) tiles represent an additional mass. To tackle this issue, so-called integrated thermal protection systems (ITPS) composed of CMC sandwich structures were introduced in the literature. The aim is to obtain a load-bearing structure that is at the same time the thermally protective layer. However, a comprehensive description of the real lightweight potential of such solutions compared to ablative materials with the corresponding sub-structures is, to the authors’ knowledge, not yet presented. Thus, based on the design of an ADD, this work aims to holistically describe such load bearing components and to compare different TPS solutions. Both thermal and preliminary mechanical designs are discussed. Additionally, a novel concept is proposed, which is based on the use of phase change materials (PCMs) embedded within a metallic sandwich structure with an additively manufactured lattice core. Such a solution can be beneficial due to the combination of both the high specific stiffness of lattice structures and the high mass-specific thermal energy storage potential of PCMs. The study is conducted with reference to the first stage of the microlauncher analysed within the European Horizon-2020 project named Recovery and Return To Base (RRTB). Full article
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21 pages, 17410 KiB  
Article
Numerical Investigation of the Detonation Cell Bifurcation with Decomposition Technique
by Pradeep Kumar Pavalavanni, Jae-Eun Kim, Min-Seon Jo and Jeong-Yeol Choi
Aerospace 2023, 10(3), 318; https://doi.org/10.3390/aerospace10030318 - 22 Mar 2023
Viewed by 1359
Abstract
Bifurcation of the characteristic cells into multiple smaller cells and decay of those cells into single large characteristic cell is observed frequently. In the present study the bifurcation phenomenon of the detonation front is investigated for marginally unstable detonations using decomposition technique. Numerical [...] Read more.
Bifurcation of the characteristic cells into multiple smaller cells and decay of those cells into single large characteristic cell is observed frequently. In the present study the bifurcation phenomenon of the detonation front is investigated for marginally unstable detonations using decomposition technique. Numerical analysis is carried out with detailed chemical kinetics for detonation propagation in H2/O2 mixtures at 10 kPa. The dynamic characteristics of the instability at the detonation front, such as the local oscillation frequency and the coherent spatial structure of the oscillation are also studied with dynamic mode decomposition (DMD) technique. The coherent structures of the primary and secondary detonation cells are analyzed during the cell bifurcation process and the mechanism in which the secondary cells are formed is investigated. It is demonstrated that the modal analysis categorizes the instability phenomena clearly and can be effectively utilized to identify the origin and source of the instability. Full article
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30 pages, 7093 KiB  
Review
UAV Platforms for Data Acquisition and Intervention Practices in Forestry: Towards More Intelligent Applications
by Huihui Sun, Hao Yan, Mostafa Hassanalian, Junguo Zhang and Abdessattar Abdelkefi
Aerospace 2023, 10(3), 317; https://doi.org/10.3390/aerospace10030317 - 22 Mar 2023
Cited by 3 | Viewed by 4757
Abstract
Unmanned air vehicle (UAV) systems for performing forestry applications have expanded in recent decades and have great economic benefits. They are validated to be more appealing than traditional platforms in various aspects, such as repeat rate, spatial resolution, and accuracy. This paper consolidates [...] Read more.
Unmanned air vehicle (UAV) systems for performing forestry applications have expanded in recent decades and have great economic benefits. They are validated to be more appealing than traditional platforms in various aspects, such as repeat rate, spatial resolution, and accuracy. This paper consolidates the state-of-the-art unmanned systems in the forestry field with a major focus on UAV systems and heterogeneous platforms, which are applied in a variety of forestry applications, such as wood production, tree quantification, disease control, wildfire management, wildlife conservation, species classification, etc. This review also studies practical applications under multiple forestry environments, including wild and managed forests, grassland, urban green parks, and stockyards. Special forest environments and terrains present customized demands for unmanned systems. The challenges of unmanned systems deployment are analyzed from environmental characterization, maneuverability and mobility improvement, and global regulatory interpretation. To better apply UAV systems into forestry, future directions are analyzed in terms of mobility enhancement and customized sensory adaption, which need to be further developed for synchronizing all possible agents into automatic functioning systems for forestry exploration. Full article
(This article belongs to the Special Issue Applications of Drones (Volume II))
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15 pages, 3580 KiB  
Article
Design, Development, and Testing of a Low-Cost Sub-Joule µPPT for a Pocket-Cube
by Farouk Smith and Jieun Bae
Aerospace 2023, 10(3), 316; https://doi.org/10.3390/aerospace10030316 - 22 Mar 2023
Viewed by 1411
Abstract
This paper presents the design and development of a sub-joule micro-Pulsed Plasma Thruster (µPPT) as a possible low-cost propulsion solution for Pocket-Cubes, used to increase its reliability, capability, and lifetime. It is shown that the µPPT successfully met Pocket-Cube design standards and additional [...] Read more.
This paper presents the design and development of a sub-joule micro-Pulsed Plasma Thruster (µPPT) as a possible low-cost propulsion solution for Pocket-Cubes, used to increase its reliability, capability, and lifetime. It is shown that the µPPT successfully met Pocket-Cube design standards and additional requirements using the iterative design method, focused mainly on simplification and improvements to a traditional PPT design, the utilization of commercial-off-the-shelf (COTS) components and 3D printing. The µPPT was designed to operate and be controlled from an Arduino UNO with a main bank energy of 0.118 J to 0.272 J and power consumption of 0.5 W. It was successfully tested for performance and lifetime in a vacuum chamber (−720 mmHg to −96 kPa) with the use of a micro-pendulum test stand and a high-speed camera. The thruster was tested for its designed operation parameters of 3.3 V and 5 V at a pulsed frequency of 0.25/0.5 Hz. The test results showed that the optimal performance of the thruster with an input voltage supply of 5 V at a pulse frequency of 0.5 Hz, achieved a minimal impulse bit of 0.698 μNs and thrust range of 0.349~1.071 μN. A comparison to the STRaND-1 3U CubeSat’s PPT performance data showed that the developed µPPT is a competitive propulsion solution, as it achieved more thrust with a similar minimal impulse bit, using only one-third of the power consumption. During the lifetime testing, the µPPT was able to produce 1980 shots. Full article
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12 pages, 493 KiB  
Communication
Angle-of-Attack Estimation for General Aviation Aircraft
by Marin Ivanković, Milan Vrdoljak, Marijan Andrić and Hrvoje Kozmar
Aerospace 2023, 10(3), 315; https://doi.org/10.3390/aerospace10030315 - 22 Mar 2023
Cited by 1 | Viewed by 1800
Abstract
The angle of attack is one of the most important flight parameters. In the framework of the present study, a flight data recording method was designed to analyze the Valasek angle-of-attack estimation method and investigate its applicability for general aviation aircraft. This was [...] Read more.
The angle of attack is one of the most important flight parameters. In the framework of the present study, a flight data recording method was designed to analyze the Valasek angle-of-attack estimation method and investigate its applicability for general aviation aircraft. This was performed using two devices characterized by substantially different characteristics. The test flight, and the ground test, i.e., a flight simulator experiment, were conducted. Two flight regimes were analyzed: (a) steady climb and descent with low values of angle of attack, (b) approach to stall with idle power with an increase of the angle of attack to the critical value. A satisfactory angle of attack estimate was obtained for the steady climb and descent regime, while the approach to stall estimate was less accurate but still indicative and considered useful for the pilot. The results indicate that less expensive synthetic sensors may provide acceptable results compared to high-quality certified equipment. A proposed modification of the estimation method enables simplification of the required equipment, while offering important information to the pilot. Full article
(This article belongs to the Collection Avionic Systems)
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14 pages, 6424 KiB  
Article
Crashworthiness Study of a Newly Developed Civil Aircraft Fuselage Section with Auxiliary Fuel Tank Reinforced with Composite Foam
by Saiaf Bin Rayhan and Xue Pu
Aerospace 2023, 10(3), 314; https://doi.org/10.3390/aerospace10030314 - 22 Mar 2023
Cited by 4 | Viewed by 2588
Abstract
Over the past two decades, aircraft crashworthiness has seen major developments, mainly with modern computing systems and commercial finite element (FE) codes. The structure and the material have been designed to absorb more kinetic energy to ensure enough safety during a controlled crash [...] Read more.
Over the past two decades, aircraft crashworthiness has seen major developments, mainly with modern computing systems and commercial finite element (FE) codes. The structure and the material have been designed to absorb more kinetic energy to ensure enough safety during a controlled crash condition. However, the fuselage section with an onboard auxiliary fuel tank requires special arrangements, since the inclined strut system with an efficient energy absorber is difficult to install under the cabin floor due to the space occupied by the fuel tank. To solve this shortcoming, a PVC composite foam along with an aluminum plate is introduced beneath the fuel tank to improve the crashworthiness metrics of the fuselage. Drop tests for both the conventional design and the proposed model are investigated by adopting the nonlinear explicit dynamics code Ansys Autodyn, with an impact velocity of 9.14 m/s. It was found that the kinetic energy absorption of the original fuselage section can be improved by 3.54% by reinforcing the foam and the plate. Moreover, they contribute to 20% of total internal energy dissipation. Numerical outcomes also suggest that the cabin floor surface experiences a 41% lower maximum stress, in addition to the mitigation of the maximum peak acceleration responses of the cabin floor at different measured locations from 6% to 36%. Full article
(This article belongs to the Section Aeronautics)
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19 pages, 6642 KiB  
Article
Retrieval of the Stratospheric Density by the Star Occultation
by Kedong Wang, Zhennan Li and Shaoxiong Zhang
Aerospace 2023, 10(3), 313; https://doi.org/10.3390/aerospace10030313 - 22 Mar 2023
Viewed by 1167
Abstract
The navigation by the stellar refraction is important for a LEO (Low-Earth-Orbit) satellite, especially in a GNSS (Global Navigation Satellite System)-denied environment, since it is totally autonomous. However, the biggest barrier to the accurate navigation by the stellar refraction lies in the accurate [...] Read more.
The navigation by the stellar refraction is important for a LEO (Low-Earth-Orbit) satellite, especially in a GNSS (Global Navigation Satellite System)-denied environment, since it is totally autonomous. However, the biggest barrier to the accurate navigation by the stellar refraction lies in the accurate stratospheric density. Therefore, the retrieval of the stratospheric density by the star occultation is proposed in this paper to acquire the stratospheric density globally with the high accuracy. Compared with the retrieval of the stratospheric density by the GPS (Global Positioning System) radio occultation, the retrieval by the star occultation can achieve a high vertical resolution. The retrieval of the stratospheric density by the star occultation is first derived in principle. Then, the performance of the retrieval, including the spatial resolution, the atmospheric attenuation, and the accuracy, was investigated in detail. The performance of the retrieval was also comprehensively verified by simulations. The simulation results prove that the retrieval of the stratospheric density by the star occultation can achieve a similar accuracy to that by the GPS radio occultation, but it has a higher vertical resolution than that by the GPS radio occultation, which is good for improving the accuracy of the navigation by the stellar refraction. Full article
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29 pages, 29147 KiB  
Article
Mechanism Underlying the Effect of Self-Circulating Casings with Different Circumferential Coverage Ratios on the Aerodynamic Performance of a Transonic Centrifugal Compressor
by Haoguang Zhang, Hao Wang, Qi Li, Fengyu Jing and Wuli Chu
Aerospace 2023, 10(3), 312; https://doi.org/10.3390/aerospace10030312 - 22 Mar 2023
Cited by 3 | Viewed by 1256
Abstract
The aim of this research was to explore the mechanisms underlying the effect of self-circulating casing treatment with different circumferential coverage ratios on the aerodynamic performance of a transonic centrifugal compressor. A three-dimensional unsteady numerical simulation was carried out on a Krain impeller. [...] Read more.
The aim of this research was to explore the mechanisms underlying the effect of self-circulating casing treatment with different circumferential coverage ratios on the aerodynamic performance of a transonic centrifugal compressor. A three-dimensional unsteady numerical simulation was carried out on a Krain impeller. The circumferential coverage ratios of the self-circulating casings were set to 36%, 54%, 72% and 90%, respectively. The numerical results showed that the Stall Margin Improvement (SMI) increased with the increase in circumferential coverage ratios. The self-circulating casing with a 90% circumferential coverage ratio exhibited the highest SMI at 20.22%. Internal flow field analysis showed that the self-circulating casing treatment improved the compressor stability by sucking the low-speed flow in the blade tip passage and restraining the leakage vortexes breaking, which caused flow blockage. The compressor performance was improved at most of the operating points, and the improvement increased with increase in circumferential coverage ratio. The improvement in compressor performance was mainly attributed to reduction in the area of the high relative total pressure loss in the blade tip passage and significant decrease in the flow loss by the self-circulating casings. Full article
(This article belongs to the Special Issue Thermal Fluid Dynamics and Control in Aerospace)
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29 pages, 7105 KiB  
Article
An Efficient and Robust Sizing Method for eVTOL Aircraft Configurations in Conceptual Design
by Osita Ugwueze, Thomas Statheros, Nadjim Horri, Michael A. Bromfield and Jules Simo
Aerospace 2023, 10(3), 311; https://doi.org/10.3390/aerospace10030311 - 21 Mar 2023
Cited by 8 | Viewed by 6778
Abstract
This paper presents the development of a robust sizing method to efficiently estimate and compare key performance parameters in the conceptual design stage for the two main classes of fully electric vertical take-off and landing (eVTOL) aircraft, the powered lift and wingless aircraft [...] Read more.
This paper presents the development of a robust sizing method to efficiently estimate and compare key performance parameters in the conceptual design stage for the two main classes of fully electric vertical take-off and landing (eVTOL) aircraft, the powered lift and wingless aircraft types. The paper investigates hybrids of classical root-finding methods: the bisection, fixed-point and Newton-Rapson methods for use in eVTOL aircraft sizing. The improved convergence efficiency of the hybrid methods is at least 70% faster than the standard methods. This improved efficiency is significant for complex sizing problems. The developed sizing method is used to investigate the comparative performance of the wingless and powered lift eVTOL aircraft types for varying mission lengths. For a generic air taxi mission with a payload of 400 kg, the powered lift type demonstrates its mass efficiency when sized for missions above 10 km in range. However, the simpler architecture of the wingless eVTOL aircraft type makes it preferable for missions below 10 km in range when considering energy efficiency. The results of the sizing study were compared against a selection of eVTOL aircraft data. The results showed a good agreement between the estimated aircraft mass using the proposed sizing method and published eVTOL aircraft data. Full article
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21 pages, 14052 KiB  
Article
Aerodynamic Thermal Simulation and Heat Flux Distribution Study of Mechanical Expansion Reentry Vehicle
by Junjie Sun, Hao Zhu, Dajun Xu and Guobiao Cai
Aerospace 2023, 10(3), 310; https://doi.org/10.3390/aerospace10030310 - 21 Mar 2023
Cited by 2 | Viewed by 1966
Abstract
The mechanical expansion reentry vehicle has become the focus of deep space exploration because of its good deceleration effect and high stability. However, due to its special aerodynamic shape, its surface heat flux characteristics are different from traditional reentry vehicles. In this paper, [...] Read more.
The mechanical expansion reentry vehicle has become the focus of deep space exploration because of its good deceleration effect and high stability. However, due to its special aerodynamic shape, its surface heat flux characteristics are different from traditional reentry vehicles. In this paper, the Two-Temperature model is introduced to simulate heat flux distribution. The influence of different structure parameters and flight parameters on the flow field structure and surface heat flux is also analyzed. The research shows that the Two-Temperature model can improve the prediction accuracy and that the heat flux may peak at the both the head and shoulder of the vehicle. Structural parameters RB, RN, and θ have an obvious negative effect on QO. RB, RN, RR, and LZ have a negative correlation with QR. QR drops first and then rises as θ increases and RS decreases. Flight parameters Ma have a positive effect on QO and QR while H is negative; α makes the heat flux distribution asymmetric. Full article
(This article belongs to the Section Astronautics & Space Science)
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21 pages, 3430 KiB  
Article
Inverse Reinforcement Learning-Based Fire-Control Command Calculation of an Unmanned Autonomous Helicopter Using Swarm Intelligence Demonstration
by Haojie Zhu, Mou Chen, Zengliang Han and Mihai Lungu
Aerospace 2023, 10(3), 309; https://doi.org/10.3390/aerospace10030309 - 20 Mar 2023
Cited by 2 | Viewed by 1415
Abstract
This paper concerns the fire-control command calculation (FCCC) of an unmanned autonomous helicopter (UAH). It determines the final effect of the UAH attack. Although many different FCCC methods have been proposed for finding optimal or near-optimal fire-control execution processes, most are either slow [...] Read more.
This paper concerns the fire-control command calculation (FCCC) of an unmanned autonomous helicopter (UAH). It determines the final effect of the UAH attack. Although many different FCCC methods have been proposed for finding optimal or near-optimal fire-control execution processes, most are either slow in calculational speed or low in attack precision. This paper proposes a novel inverse reinforcement learning (IRL) FCCC method to calculate the fire-control commands in real time without losing precision by considering wind disturbance. First, the adaptive step velocity-verlet iterative algorithm-based ballistic determination method is proposed for calculation of the impact point of the unguided projectile under wind disturbance. In addition, a swarm intelligence demonstration (SID) model is proposed to demonstrate teaching; this model is based on an improved particle swarm optimization (IPSO) algorithm. Benefiting from the global optimization capability of the IPSO algorithm, the SID model often leads to an exact solution. Furthermore, a reward function neural network (RFNN) is trained according to the SID model, and a reinforcement learning (RL) model using RFNN is used to generate the fire-control commands in real time. Finally, the simulation results verify the feasibility and effectiveness of the proposed FCCC method. Full article
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13 pages, 741 KiB  
Article
Lyapunov-Based Impact Time Control Guidance Law with Performance Prediction
by Hyeong-Geun Kim and Jongho Shin
Aerospace 2023, 10(3), 308; https://doi.org/10.3390/aerospace10030308 - 20 Mar 2023
Viewed by 1134
Abstract
This paper proposes an impact time control guidance law based on exact nonlinear kinematics equations. To address the impact time control problem of providing enhanced intercept accuracy, we formulated an error variable whose regulation ensures the fulfillment of the required tasks without time-to-go [...] Read more.
This paper proposes an impact time control guidance law based on exact nonlinear kinematics equations. To address the impact time control problem of providing enhanced intercept accuracy, we formulated an error variable whose regulation ensures the fulfillment of the required tasks without time-to-go estimation. Based on the Lyapunov stability theory, a desired line-of-sight rate profile that satisfies the convergence of the error variable was constructed, from which the guidance command was designed using the optimal tracking formulation. The simple structure of the proposed guidance law enables the prediction of interceptor behavior during homing, thereby allowing the interceptor to maneuver along feasible trajectories. In addition, although the structure of the proposed guidance law is simple and similar to that of proportional navigation, it is theoretically guaranteed to execute the required mission precisely at the end of homing. Numerical simulations demonstrated that the proposed guidance law achieved effective target interception under various terminal constraint settings. Full article
(This article belongs to the Section Aeronautics)
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24 pages, 12479 KiB  
Review
A Review of Aeroengines’ Bolt Preload Formation Mechanism and Control Technology
by Zhaoyu Li, Xiaoqiang Li, Yujie Han, Pengfei Zhang, Zongjiang Zhang, Mingming Zhang and Gang Zhao
Aerospace 2023, 10(3), 307; https://doi.org/10.3390/aerospace10030307 - 20 Mar 2023
Cited by 1 | Viewed by 3390
Abstract
The bolt connection structure is widely used in the connection of aeroengine parts, and its connection quality is very important, as it can directly affect the geometric and dynamic performance of the aeroengine. Taking the bolt preload as the entry point, the research [...] Read more.
The bolt connection structure is widely used in the connection of aeroengine parts, and its connection quality is very important, as it can directly affect the geometric and dynamic performance of the aeroengine. Taking the bolt preload as the entry point, the research status of bolted aeroengine connections in recent years is summarized based on the bolt preload formation mechanism and control technology in this review. For the research of the preload formation mechanism, single and multiple bolts of aeroengine bolt arrays are analyzed. According to the characteristics of aeroengine bolt connections, the research of aeroengine bolt preload control technology is divided into two parts: bolt tightening technology, and bolt tightening equipment. Finally, based on the summarization of the research, the future research prospects are evaluated and discussed. Full article
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21 pages, 3269 KiB  
Article
RANS-Based Aeroacoustic Global Sensitivity Study and Optimization of UAV Propellers
by Witold Klimczyk and Adam Sieradzki
Aerospace 2023, 10(3), 306; https://doi.org/10.3390/aerospace10030306 - 20 Mar 2023
Cited by 3 | Viewed by 1858
Abstract
Modeling of Unmanned Aerial Vehicles (UAV) propellers in a global, multidisciplinary aeroacoustic optimization was investigated. The modeling consists of three aspects: geometry, aerodynamics, and aeroacoustics. Firstly, a parametric geometry model was established using chord, twist, and sweep distributions along the radius, defined by [...] Read more.
Modeling of Unmanned Aerial Vehicles (UAV) propellers in a global, multidisciplinary aeroacoustic optimization was investigated. The modeling consists of three aspects: geometry, aerodynamics, and aeroacoustics. Firstly, a parametric geometry model was established using chord, twist, and sweep distributions along the radius, defined by splines to ensure smoothness. Additionally, airfoil parameters including maximum camber and its position, as well as the position of maximum thickness, were added. Secondly, a blade geometry-resolved aerodynamic model based on steady RANS was established. A two-equation SST turbulence model was used for compressible flow with periodic boundary conditions. Thirdly, an aeroacoustic model for far-field tonal noise calculation was defined, based on the Ffowcs Williams and Hawkings analogy and a RANS solution. A global sensitivity analysis was performed to establish the importance of individual design variables. Consequently, surrogate modeling-based optimization strategy was devised to efficiently establish Pareto front of propeller geometries in multi-objective aeroacoustic optimization. Full article
(This article belongs to the Special Issue Aeroacoustics and Noise Mitigation)
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30 pages, 49090 KiB  
Article
GIS-Based Determination of the Optimal Heliport and Water Source Locations for Forest Fire Suppression Using Multi-Objective Programming
by Erdem Emin Maraş, Kadir Dönmez and Yeliz Emecen
Aerospace 2023, 10(3), 305; https://doi.org/10.3390/aerospace10030305 - 19 Mar 2023
Cited by 4 | Viewed by 1774
Abstract
First responders to forest fires, especially in areas that cannot be reached by land, are carried out by helicopters. In large forest lands, the necessity of helicopters to reach fire areas in the shortest time reveals the importance of heliport locations. In this [...] Read more.
First responders to forest fires, especially in areas that cannot be reached by land, are carried out by helicopters. In large forest lands, the necessity of helicopters to reach fire areas in the shortest time reveals the importance of heliport locations. In this study, the set-covering problem is handled by optimizing heliport locations in a heavily forested Milas district of Muğla, Turkey, where forest fires have occurred severely in recent years. The aim is to cover the entire region with a minimum number of heliports within specified response times. The forest density of the relevant region is integrated as weights into the mathematical model based on geographic information systems (GIS) during location-allocation. In addition, several conditions related to the study area, such as their proximity to roads, distance to settlement areas, slope, wetlands, altitude, the existence of heliports or airports, and others, were defined on 2 × 2 km grids and analyzed in ArcGIS for use in mathematical modeling, which was developed as a multi-objective programming model. In the first model, different initial attack (IA) times are considered, and the tradeoffs between IA time coverages and heliport locations are revealed by using the ɛ constraint method. Then, in the second model, the water sources are evaluated to provide recommendations for further extended attack (EA) and additional water sources (pools) considering the existing ones. Mathematical modeling is used to determine Pareto optimal heliport and additional water source locations for both IA and EA in the forest fires, respectively. Finally, the potential savings of the proposed model are quantified by comparing the model results with the current locations of the helicopters and water sources based on historical fire data. Full article
(This article belongs to the Collection Air Transportation—Operations and Management)
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17 pages, 1615 KiB  
Article
Feasibility Analysis of Autonomous Orbit Determination and Gravity-Field Recovery around Asteroids Using Inter-Satellite Range Data
by Haohan Li and Xiyun Hou
Aerospace 2023, 10(3), 304; https://doi.org/10.3390/aerospace10030304 - 19 Mar 2023
Viewed by 1254
Abstract
Autonomous navigation and orbit determination are key problems of asteroid exploration missions. Inter-satellite range link is a type of measurement widely used in the orbit determination of Earth satellites, but not so widely used in missions around small bodies. In our study, we [...] Read more.
Autonomous navigation and orbit determination are key problems of asteroid exploration missions. Inter-satellite range link is a type of measurement widely used in the orbit determination of Earth satellites, but not so widely used in missions around small bodies. In our study, we assume that highly accurate inter-satellite range data can be obtained around small bodies between the chief spacecraft and some low-cost deputies, and study the feasibility of simultaneous autonomous orbit determination of the spacecraft and the gravity-field recovery without the support from ground stations. After the feasibility analysis, two modified methods are proposed. Both methods demonstrate obvious improvements in both the convergence region and the accuracy. One remark is that the inter-satellite range data can be also used together with various observation data from ground stations to enhance the accuracy of the determined orbits and the gravity field. Full article
(This article belongs to the Special Issue Dynamics and Control Problems on Asteroid Explorations)
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69 pages, 38982 KiB  
Article
Predictive Analysis of Airport Safety Performance: Case Study of Split Airport
by Dajana Bartulović and Sanja Steiner
Aerospace 2023, 10(3), 303; https://doi.org/10.3390/aerospace10030303 - 17 Mar 2023
Cited by 5 | Viewed by 1633
Abstract
A predictive safety management methodology implies steps and tools of predictive safety management in aviation, i.e., use of predictive (forecasting) and causal modeling methods to identify potential and possible hazards in the future, as well as their causal factors which can help define [...] Read more.
A predictive safety management methodology implies steps and tools of predictive safety management in aviation, i.e., use of predictive (forecasting) and causal modeling methods to identify potential and possible hazards in the future, as well as their causal factors which can help define timely and efficient mitigation measures to prevent or restrain emerging hazards turning into adverse events. The focus of this paper is to show how predictive analysis of an organization’s safety performance can be conducted, on the sample airport. A case study regarding implementation of predictive analysis of an organization’s safety performance, was performed at Split Airport. The predictive analysis of an airport’s safety performance was conducted through the analysis of Split Airport safety database, causal modeling of Split Airport organizational and safety performance indicators, outlier root cause analysis of Split Airport safety performance indicators, predictive analysis of safety performance (forecasting of Split Airport organizational and safety performance indicators), and scenario cases that simulate future behavior of Split Airport safety performance indicators. Based on detected future hazards, and their causal factors, the appropriate mitigation measures are proposed for the purpose of improving and maintaining an acceptable level of safety at the airport. Full article
(This article belongs to the Collection Air Transportation—Operations and Management)
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25 pages, 9199 KiB  
Article
Numerical Stabilization for Flutter Analysis Procedure
by Weixing Yuan and Xiaoyang Zhang
Aerospace 2023, 10(3), 302; https://doi.org/10.3390/aerospace10030302 - 17 Mar 2023
Cited by 3 | Viewed by 2353
Abstract
Severe mode switching is often observed when the PK-method is used in the flutter analysis of complex aircraft configurations, in particular when nearly 100 vibrational modes are considered. In the commonly used commercial software NASTRAN, the resulting eigenroots are sorted in an ascending [...] Read more.
Severe mode switching is often observed when the PK-method is used in the flutter analysis of complex aircraft configurations, in particular when nearly 100 vibrational modes are considered. In the commonly used commercial software NASTRAN, the resulting eigenroots are sorted in an ascending order of frequency. Therefore, the appearance of massive mode-switching instances cannot be avoided in the PK-method flutter analyses, especially for engineering applications with real-world complex configurations. In this study, as a post-processing procedure, an extensive sorting capability was developed in order to compensate for NASTRAN’s lack of a mode-tracking procedure in between the airspeed steps. The capability was developed based on both the complex eigenvalues and their corresponding eigenvectors. In addition, numerical techniques commonly used in computational fluid dynamics (CFD) were introduced to improve the convergence of the traditional PK-method. A hybrid approach was applied to the initial guess of the reduced frequency, followed by a deferred correction scheme for the PK-iteration process. Additionally, mode matching was specifically addressed when locking eigenroots onto the aerodynamics within the PK iterations. In addition to the PK iterations, a damping iteration or modified g-method was implemented by extending the PK-method solver. The combination of these special techniques effectively improved the numerical stability of the iterations in the stability eigensolution process and significantly reduced the appearance of the misleading mode switching, minimizing risks in aircraft flight. Full article
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12 pages, 5264 KiB  
Article
Probabilistic Failure Risk of Aeroengine Life-Limited Parts Considering the Random Load Interference Effect
by Guo Li, Shuchun Huang, Wanqiu Lu, Junbo Liu, Shuiting Ding, Gong Zhang and Bo Zhen
Aerospace 2023, 10(3), 301; https://doi.org/10.3390/aerospace10030301 - 17 Mar 2023
Cited by 1 | Viewed by 1187
Abstract
Probabilistic failure risk analysis of aeroengine life-limited parts is of great significance for flight safety. Current probabilistic failure risk analysis uses equal amplitude load calculations for conservative estimation, avoiding inclusion of the interference effect analyzing random loads due to its massive computational complexity [...] Read more.
Probabilistic failure risk analysis of aeroengine life-limited parts is of great significance for flight safety. Current probabilistic failure risk analysis uses equal amplitude load calculations for conservative estimation, avoiding inclusion of the interference effect analyzing random loads due to its massive computational complexity and leading to reduced analysis accuracy. Here, an efficient algorithm is established to solve this computational problem, and an analytical framework is established to consider the interference effect of variable amplitude load. The corresponding probabilistic failure risk analysis is performed for the centrifugal compressor disk. The results show that considering the interference effect of random variable amplitude loads causes a significant decrease in the risk of failure, and the efficient algorithm has advantages over the Monte Carlo sampling method in accuracy and efficiency when considering load interference. This work provides a reference for exploring the probabilistic damage tolerance method under complex loads and supports the optimal design of life-limited parts. Full article
(This article belongs to the Section Aeronautics)
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17 pages, 1144 KiB  
Article
Functional Hazard Assessment of a Modular Re-Configurable Morphing Wing Using Taguchi and Finite Element Methodologies
by Faisal Mahmood, Seyed M. Hashemi and Hekmat Alighanbari
Aerospace 2023, 10(3), 300; https://doi.org/10.3390/aerospace10030300 - 17 Mar 2023
Viewed by 1542
Abstract
Growing concerns over the CO2 footprint due the exponential demand of the aviation industry, along with the requirements for high aerodynamic performance, cost saving, and manoeuvrability during different phases of a flight, pave the path towards adaptable wing design. Morphing wing design [...] Read more.
Growing concerns over the CO2 footprint due the exponential demand of the aviation industry, along with the requirements for high aerodynamic performance, cost saving, and manoeuvrability during different phases of a flight, pave the path towards adaptable wing design. Morphing wing design encompasses most, if not all, of the flight condition variations, and can respond interactively. However, functional failure of the morphing wing might bring devastating impacts on the passengers, crew, and/or aircraft. In the present work, the dynamic characteristics of a re-configurable modular morphing wing developed in-house by a research group at the Toronto Metropolitan University, are investigated from the perspective of a functional hazard assessment (FHA). This modular morphing wing, developed based on the idea of a parallel robot, consists of a number of structural elements connected to each other and to the wing ribs through eye-bolt joints. Timoshenko’s bending beam theory, in conjunction with the finite element method (FEM), is exploited to model the structural members. Possible hazards, assumed here to be the structural failure of the beam components, have been identified and their failure conditions are assessed. Numerical simulations have been presented to show the impact of various combinations of the identified hazards on the vibration signature of the morphing wing in unmorphed and morphed configurations. Identification of changes in the wing’s vibration signature is a vital component in the fail-safe structural and aeroelastic design of an aircraft. The present study is geared towards the structural response of the system in the absence of any aerodynamic loads. Full article
(This article belongs to the Special Issue Morphing Aircraft)
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20 pages, 18394 KiB  
Article
Laser-Induced Ignition and Combustion of Single Micron-Sized Al-Li Alloy Particles in High Pressure Air/N2
by Dunhui Xu, Fang Wang, Shengji Li, Xuefeng Huang, Heping Li and Yanhui Guo
Aerospace 2023, 10(3), 299; https://doi.org/10.3390/aerospace10030299 - 17 Mar 2023
Cited by 8 | Viewed by 1940
Abstract
To solve the problems associated with micron-sized aluminum (Al), including sintering, agglomeration, and slag deposition during the combustion of aluminized propellants, aluminum–lithium (Al-Li) alloy, prepared by introducing a small amount of Li (1.0 wt.%) into Al, was used in place of Al. Then, [...] Read more.
To solve the problems associated with micron-sized aluminum (Al), including sintering, agglomeration, and slag deposition during the combustion of aluminized propellants, aluminum–lithium (Al-Li) alloy, prepared by introducing a small amount of Li (1.0 wt.%) into Al, was used in place of Al. Then, the ignition and combustion characteristics of single micron-sized Al-Li alloy particles were investigated in detail using a self-built experimental apparatus and multiple characterization methods. The ignition probability, ignition delay time, flame propagation rate, burn time, combustion temperature, flame radiation spectra, and microexplosion characteristics were obtained. The TG-DSC results demonstrated that, as compared to the counterpart Al, the Al-Li alloy had a lower ignition temperature. The emission lines of AlO revealed the gas-phase combustion of the Al-Li alloy, and thus the Al-Li alloy exhibited a mixed combustion mode, including surface combustion and gas-phase combustion. Moreover, during combustion, a microexplosion occurred, which increased the combustion rate and reduced the burn lifetime. The ambient pressure had a significant effect on the ignition and combustion characteristics of the Al-Li alloy, and the ignition delay time and burn time exponentially decreased as the ambient pressure enhanced. The combustion temperature of the Al-Li alloy at atmospheric pressure was slightly higher than those at elevated pressures. The Al-Li alloy burned in N2, but no microexplosion was observed. Finally, the ignition and combustion mechanism of the Al-Li alloy in air was demonstrated by combining SEM, EDS, and XRD analyses of the material and residues. The results suggest that the addition of Li promoted the combustion performance of Al by changing the surface structure of the oxide film and the combustion mode. Full article
(This article belongs to the Special Issue Combustion Evaluation and Control of Solid Rocket Motors)
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15 pages, 5382 KiB  
Article
A Multi-View Vision System for Astronaut Postural Reconstruction with Self-Calibration
by Shuwei Gan, Xiaohu Zhang, Sheng Zhuge, Chenghao Ning, Lijun Zhong and You Li
Aerospace 2023, 10(3), 298; https://doi.org/10.3390/aerospace10030298 - 17 Mar 2023
Cited by 2 | Viewed by 1488
Abstract
Space exploration missions involve significant participation from astronauts. Therefore, it is of great practical importance to assess the astronauts’ performance via various parameters in the cramped and weightless space station. In this paper, we proposed a calibration-free multi-view vision system for astronaut performance [...] Read more.
Space exploration missions involve significant participation from astronauts. Therefore, it is of great practical importance to assess the astronauts’ performance via various parameters in the cramped and weightless space station. In this paper, we proposed a calibration-free multi-view vision system for astronaut performance capture, including two modules: (1) an alternating iterative optimization of the camera pose and human pose is implemented to calibrate the extrinsic camera parameters with detected 2D keypoints. (2) Scale factors are restricted by the limb length to recover the real-world scale and the shape parameters are refined for subsequent postural reconstruction. These two modules can provide effective and efficient motion capture in a weightless space station. Extensive experiments using public datasets and the ground verification test data demonstrated the accuracy of the estimated camera pose and the effectiveness of the reconstructed human pose. Full article
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25 pages, 2020 KiB  
Article
A Machine Learning and Feature Engineering Approach for the Prediction of the Uncontrolled Re-Entry of Space Objects
by Francesco Salmaso, Mirko Trisolini and Camilla Colombo
Aerospace 2023, 10(3), 297; https://doi.org/10.3390/aerospace10030297 - 17 Mar 2023
Cited by 2 | Viewed by 1979
Abstract
The continuously growing number of objects orbiting around the Earth is expected to be accompanied by an increasing frequency of objects re-entering the Earth’s atmosphere. Many of these re-entries will be uncontrolled, making their prediction challenging and subject to several uncertainties. Traditionally, re-entry [...] Read more.
The continuously growing number of objects orbiting around the Earth is expected to be accompanied by an increasing frequency of objects re-entering the Earth’s atmosphere. Many of these re-entries will be uncontrolled, making their prediction challenging and subject to several uncertainties. Traditionally, re-entry predictions are based on the propagation of the object’s dynamics using state-of-the-art modelling techniques for the forces acting on the object. However, modelling errors, particularly related to the prediction of atmospheric drag, may result in poor prediction accuracies. In this context, we explored the possibility of performing a paradigm shift, from a physics-based approach to a data-driven approach. To this aim, we present the development of a deep learning model for the re-entry prediction of uncontrolled objects in Low Earth Orbit (LEO). The model is based on a modified version of the Sequence-to-Sequence architecture and is trained on the average altitude profile as derived from a set of Two-Line Element (TLE) data of over 400 bodies. The novelty of the work consists in introducing in the deep learning model, alongside the average altitude, and three new input features: a drag-like coefficient (B*), the average solar index, and the area-to-mass ratio of the object. The developed model was tested on a set of objects studied in the Inter-Agency Space Debris Coordination Committee (IADC) campaigns. The results show that the best performances are obtained on bodies characterised by the same drag-like coefficient and eccentricity distribution as the training set. Full article
(This article belongs to the Section Astronautics & Space Science)
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23 pages, 8204 KiB  
Article
A Multivariable Method for Calculating Failure Probability of Aeroengine Rotor Disk
by Guo Li, Junbo Liu, Liu Yang, Huimin Zhou and Shuiting Ding
Aerospace 2023, 10(3), 296; https://doi.org/10.3390/aerospace10030296 - 16 Mar 2023
Viewed by 1237
Abstract
The probabilistic damage tolerance analysis of aeroengine rotor disks is essential for determining if the disk is safe. To calculate the probability of failure, the numerical integration method is efficient if the integral formula of the probability density function is known. However, obtaining [...] Read more.
The probabilistic damage tolerance analysis of aeroengine rotor disks is essential for determining if the disk is safe. To calculate the probability of failure, the numerical integration method is efficient if the integral formula of the probability density function is known. However, obtaining an accurate integral formula for aeroengine disks is generally complicated due to their complex failure mechanism. This article proposes a multivariable numerical integral method for calculating the probability of failure. Three random variables (initial defect length a, life scatter factor S, and stress scatter factor B) are considered. A compressor disk model is evaluated. The convergence, efficiency, and accuracy of the proposed method are compared with the Monte Carlo simulation and importance sampling method. The results show that the integral-based method is 100 times more efficient under the same convergence and accuracy conditions. Full article
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16 pages, 7082 KiB  
Article
RAMSEES: A Model of the Atmospheric Radiative Environment Based on Geant4 Simulation of Extensive Air Shower
by Hugo Cintas, Frédéric Wrobel, Marine Ruffenach, Damien Herrera, Frédéric Saigné, Athina Varotsou, Françoise Bezerra and Julien Mekki
Aerospace 2023, 10(3), 295; https://doi.org/10.3390/aerospace10030295 - 16 Mar 2023
Viewed by 1644
Abstract
The device downscaling of electronic components has given rise to the need to consider specific failures in onboard airplane electronics. Single Event Effects (SEE) are a kind of failures that occur due to radiation in the atmosphere. For the purpose of ensuring onboard [...] Read more.
The device downscaling of electronic components has given rise to the need to consider specific failures in onboard airplane electronics. Single Event Effects (SEE) are a kind of failures that occur due to radiation in the atmosphere. For the purpose of ensuring onboard electronic reliability, there is a clear need for new tools to predict the SEE rate, at both avionic altitudes and at ground level. In this work, we develop a new tool: RAMSEES (Radiation Atmospheric Model for SEE Simulation), which simulates the atmospheric radiative environment induced by cosmic rays. This multiscale and multi-physics phenomenon is simulated using the Geant4 toolkit, allowing the creation of a database to characterize the radiation environment in the atmosphere as a function of altitude. We show the need to simulate very high-energy particles such as 100 TeV space protons, because they are the main contributor of radiation at avionic altitudes as well as at ground level. Our approach shows a good agreement with the experimental data, the standards, and other models, and it also points out some discrepancies, especially below 18 km of altitude. RAMSEES can be the basis of the estimation of the SEE rate from ground level to the stratosphere, at any given position and time. Full article
(This article belongs to the Collection Avionic Systems)
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16 pages, 13112 KiB  
Article
Design of Large-Scale Space Lattice Structure with Near-Zero Thermal Expansion Metamaterials
by Bin Yu, Zhao Xu, Ruinan Mu, Anping Wang and Haifeng Zhao
Aerospace 2023, 10(3), 294; https://doi.org/10.3390/aerospace10030294 - 16 Mar 2023
Cited by 7 | Viewed by 2105
Abstract
Thermal expansion is inevitable for space structures under the alternating temperature of outer space around the earth. This may lead to the thermal stress and deformation due to the mismatch of the coefficient of thermal expansion. Near-zero thermal expansion (Near-ZTE) is a vitally [...] Read more.
Thermal expansion is inevitable for space structures under the alternating temperature of outer space around the earth. This may lead to the thermal stress and deformation due to the mismatch of the coefficient of thermal expansion. Near-zero thermal expansion (Near-ZTE) is a vitally essential demand for large-scale space telescopes or antennas to preserve their spatial precision and resolution. Recently, mechanical metamaterials with superior and tailorable properties have attracted significant interest with regard to developing negative materials or ultra-property materials. In this paper, the near-ZTE space structure architected by a dual-hourglass bi-material lattice is achieved by the structural optimization method with the gradient-based algorithm. First, an hourglass lattice with adjustable structural parameters is optimized to seek the design of effective negative thermal expansion (NTE) in the thickness direction. Then, two building blocks with both NTE and legacy positive thermal expansion (PTE) are combined as a dual-layered lattice to obtain the near-ZTE. Finally, a structure with near-ZTE of about ~10−9 m/(m·K) is obtained. Furthermore, the various lattice configurations, such as the hexagonal pyramid and triangle pyramid, are investigated in detail. Finally, the natural frequencies of two near-ZTE lattices are calculated by the modal analysis method, and the stiffness is discussed for the optimal solution of space applications. This work demonstrates that the near-ZTE structure can be achieved by utilizing the negative metamaterial and structural optimization method. It provides a novel solution to design the large-scale space structures with the near-zero thermal induced deformation, and may be constructed and assembled by the on-orbit fabrication technology. Full article
(This article belongs to the Special Issue Advanced Spacecraft/Satellite Technologies)
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17 pages, 679 KiB  
Article
A Model-Based Prognostic Framework for Electromechanical Actuators Based on Metaheuristic Algorithms
by Leonardo Baldo, Ivana Querques, Matteo Davide Lorenzo Dalla Vedova and Paolo Maggiore
Aerospace 2023, 10(3), 293; https://doi.org/10.3390/aerospace10030293 - 16 Mar 2023
Cited by 1 | Viewed by 1784
Abstract
The deployment of electro-mechanical actuators plays an important role towards the adoption of the more electric aircraft (MEA) philosophy. On the other hand, a seamless substitution of EMAs, in place of more traditional hydraulic solutions, is still set back, due to the shortage [...] Read more.
The deployment of electro-mechanical actuators plays an important role towards the adoption of the more electric aircraft (MEA) philosophy. On the other hand, a seamless substitution of EMAs, in place of more traditional hydraulic solutions, is still set back, due to the shortage of real-life and reliability data regarding their failure modes. One way to work around this problem is providing a capillary EMA prognostics and health management (PHM) system capable of recognizing failures before they actually undermine the ability of the safety-critical system to perform its functions. The aim of this work is the development of a model-based prognostic framework for PMSM-based EMAs leveraging a metaheuristic algorithm: the evolutionary (differential evolution (DE)) and swarm intelligence (particle swarm (PSO), grey wolf (GWO)) methods are considered. Several failures (dry friction, backlash, short circuit, eccentricity, and proportional gain) are simulated by a reference model, and then detected and identified by the envisioned prognostic method, which employs a low fidelity monitoring model. The paper findings are analysed, showing good results and proving that this strategy could be executed and integrated in more complex routines, supporting EMAs adoption, with positive impacts on system safety and reliability in the aerospace and industrial field. Full article
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25 pages, 14449 KiB  
Article
Numerical Study of Unstable Shock-Induced Combustion with Different Chemical Kinetics and Investigation of the Instability Using Modal Decomposition Technique
by Pradeep Kumar Pavalavanni, Min-Seon Jo, Jae-Eun Kim and Jeong-Yeol Choi
Aerospace 2023, 10(3), 292; https://doi.org/10.3390/aerospace10030292 - 15 Mar 2023
Cited by 3 | Viewed by 1427
Abstract
An unstable shock-induced combustion (SIC) case around a hemispherical projectile has been numerically studied which experimentally produced a regular oscillation. Comparison of detailed H2/O2 reaction mechanisms is made for the numerical simulation of SIC with higher-order numerical schemes intended for [...] Read more.
An unstable shock-induced combustion (SIC) case around a hemispherical projectile has been numerically studied which experimentally produced a regular oscillation. Comparison of detailed H2/O2 reaction mechanisms is made for the numerical simulation of SIC with higher-order numerical schemes intended for the use of the code for the hypersonic propulsion and supersonic combustion applications. The simulations show that specific reaction mechanisms are grid-sensitive and produce spurious reactions in the high-temperature region, which trigger artificial instability in the oscillating flow field. The simulations also show that specific reaction mechanisms develop such spurious oscillations only at very fine grid resolutions. The instability mechanism is investigated using the dynamic mode decomposition (DMD) technique and the spatial structure of the decomposed modes are further analyzed. It is found that the instability triggered by the high-temperature reactions strengthens the reflecting compression wave and pushes the shock wave further and disrupts the regularly oscillating mechanism. The spatial coherent structure from the DMD analysis shows the effect of this instability in different regions in the regularly oscillating flow field. Full article
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