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Keywords = pitching airfoil

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18 pages, 4564 KiB  
Article
Multi-Fidelity Modeling of Isolated Hovering Rotors
by Jason Cornelius, Nicholas Peters, Tove Ågren and Hugo Hjelm
Aerospace 2025, 12(8), 650; https://doi.org/10.3390/aerospace12080650 - 22 Jul 2025
Viewed by 212
Abstract
Surrogate modeling has been rapidly evolving in the field of aerospace engineering, further reducing the cost of computational analyses. These models often require large amounts of information to learn the underlying process, which is at odds with obtaining and using the highest-fidelity data. [...] Read more.
Surrogate modeling has been rapidly evolving in the field of aerospace engineering, further reducing the cost of computational analyses. These models often require large amounts of information to learn the underlying process, which is at odds with obtaining and using the highest-fidelity data. This study assesses the efficacy of multi-fidelity modeling (MFM) to improve simulation accuracy while reducing computational cost. A database of hovering rotor simulations with perturbations of the rotor design and operating conditions was first generated using two different fidelity levels of the OVERFLOW 2.4D Computational Fluid Dynamics software. MFM was then used to quantify the effectiveness of this approach for the development of accurate surrogate models. Multi-fidelity models based on Gaussian Process Regression (GPR) were derived for hovering rotor performance prediction given the geometric rotor blade inputs that currently include twist, planform, airfoil, and the collective pitch angle. The MFM approach was consistently more accurate at predicting the hold-out test data than the surrogate model with high-fidelity data alone. An MFM using just 20% of the available high-fidelity training data was as accurate as a solely high-fidelity model trained on 80% of the available data, representing an approximate fourfold reduction in computational cost. Full article
(This article belongs to the Special Issue Recent Advances in Applied Aerodynamics (2nd Edition))
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27 pages, 8289 KiB  
Article
A High-Efficient Modeling Method for Aerodynamic Loads of an Airfoil with Active Leading Edge Based on RFA and CFD
by Shengyong Fang, Sheng Zhang, Jinlong Zhou and Weidong Yang
Aerospace 2025, 12(7), 632; https://doi.org/10.3390/aerospace12070632 - 15 Jul 2025
Viewed by 296
Abstract
For the airfoil in freestream, the pressure difference between the upper and lower surfaces and the variations in pressure gradients are significant at its leading edge area. Under reasonable deflections, the active leading edge can effectively change airfoil aerodynamic loads, which helps to [...] Read more.
For the airfoil in freestream, the pressure difference between the upper and lower surfaces and the variations in pressure gradients are significant at its leading edge area. Under reasonable deflections, the active leading edge can effectively change airfoil aerodynamic loads, which helps to improve the rotor aerodynamic performance. In this paper, a modeling method for an airfoil with an active leading edge was developed to calculate its aerodynamic loads. The pitch motion of the rotor blade and the leading edge deflections were taken into account. Firstly, simulations of steady and unsteady flow for the airfoil with an active leading edge were conducted under different boundary conditions and with different leading edge deflection movement. Secondly, the rational function approximation (RFA) was employed to establish the relationship between aerodynamic loads and airfoil/active leading edge deflections. Then, coefficient matrices of the RFA approach were identified based on a limited number of high-fidelity computational fluid dynamics (CFD) results. Finally, an aerodynamic model of the airfoil with an active leading edge was developed, and its accuracy was validated by comparing it to the high-fidelity CFD results. Comparative results reveal that the developed model can calculate the aerodynamic loads of an airfoil with an active leading edge accurately and efficiently when applied appropriately. The modeling method can be used in aerodynamic load calculations and the aeroelastic coupling analysis of a rotor with active control devices. Full article
(This article belongs to the Section Aeronautics)
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23 pages, 11585 KiB  
Article
Dynamic Stall Mechanisms of Pitching Airfoil: IDDES Study Across Different Mach Numbers
by Simeng Jing, Fan Lu, Li Ma, Qijun Zhao and Guoqing Zhao
Appl. Sci. 2025, 15(13), 7309; https://doi.org/10.3390/app15137309 - 28 Jun 2025
Viewed by 388
Abstract
This study investigates dynamic stall mechanisms of a pitching NACA 0012 airfoil through high-fidelity computational fluid dynamics (CFD) simulations. The improved delayed detached eddy simulation (IDDES) method based on a sliding mesh system is constructed and validated against experimental airload measurements. The results [...] Read more.
This study investigates dynamic stall mechanisms of a pitching NACA 0012 airfoil through high-fidelity computational fluid dynamics (CFD) simulations. The improved delayed detached eddy simulation (IDDES) method based on a sliding mesh system is constructed and validated against experimental airload measurements. The results demonstrate a good agreement and the capability to capture three-dimensional flow structures. Comparative analyses at two Mach numbers of 0.283 and 0.5 reveal distinct stall physics. At the Mach number of 0.283, a notable 9.7° delay is observed between the static and dynamic stall. The airfoil experiences a leading-edge stall dominated by a strong adverse pressure gradient and generates rapid airload variations. In addition, trailing-edge vortex (TEV) and secondary leading-edge vortices (LEVs) induce distinct airload fluctuations. After the shedding of primary vortices, secondary vortices develop. In contrast, the airfoil at the Mach number of 0.5 presents a reduced stall delay of 6.4° and a shock-induced dynamic stall characterized by dispersed, smaller vortices, which results in mild airload variations during stall. Aerodynamic damping analysis identifies stall delay as a primary contributor to negative damping. Enhanced pitching stability at the higher Mach number correlates with reduced stall delay and different LEV development characteristics. Results across varying reduced frequencies show that increasing reduced frequency delays the aerodynamic response and stall onset. At Ma = 0.283, this increasement promotes a divergent tendency in pitching motion, whereas at Ma = 0.5, it induces greater oscillatory stability attributed to distinct stall characteristics. Full article
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27 pages, 5476 KiB  
Article
The Harmonic Pitching NACA 0018 Airfoil in Low Reynolds Number Flow
by Jan Michna, Maciej Śledziewski and Krzysztof Rogowski
Energies 2025, 18(11), 2884; https://doi.org/10.3390/en18112884 - 30 May 2025
Viewed by 413
Abstract
This study investigates the aerodynamic performance of a symmetric NACA 0018 airfoil under harmonic pitching motions at low Reynolds numbers, a regime characterized by the presence of laminar separation bubbles and their impact on aerodynamic forces. The analysis encompasses oscillation frequencies of 1 [...] Read more.
This study investigates the aerodynamic performance of a symmetric NACA 0018 airfoil under harmonic pitching motions at low Reynolds numbers, a regime characterized by the presence of laminar separation bubbles and their impact on aerodynamic forces. The analysis encompasses oscillation frequencies of 1 Hz, 2 Hz, and 13.3 Hz, with amplitudes of 4° and 8°, along with steady-state simulations conducted for angles of attack up to 20° to validate the numerical model. The results reveal that the γ-Reθ turbulence model provides improved predictions of aerodynamic forces at higher Reynolds numbers but struggles at lower Reynolds numbers, where laminar flow effects dominate. The inclusion of the 13.3 Hz frequency, relevant to Darrieus vertical-axis wind turbines, demonstrates the effectiveness of the model in capturing dynamic hysteresis loops and reduced oscillations, in contrast to the k-ω SST model. Comparisons with XFOIL further highlight the challenges in accurately modeling laminar-to-turbulent transitions and dynamic flow phenomena. These findings offer valuable insights into the aerodynamic behavior of thick airfoils under low Reynolds number conditions and contribute to the advancement of turbulence modeling, particularly in applications involving vertical-axis wind turbines. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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30 pages, 5700 KiB  
Article
Two-Stage Global–Local Aerodynamic/Stealth Optimization Method Based on Space Decomposition
by Wei Zhang, Lin Zhou, Bowen Shu, Xian Chen, Zhenghong Gao and Jiangtao Huang
Aerospace 2025, 12(6), 488; https://doi.org/10.3390/aerospace12060488 - 29 May 2025
Viewed by 393
Abstract
The design of the flying wing airfoil must consider aerodynamic stealth and trim requirements, with their coupling exacerbating the complexity of the design problem by introducing multiple local minimum points in design space. In addition, it would need a broad space with high [...] Read more.
The design of the flying wing airfoil must consider aerodynamic stealth and trim requirements, with their coupling exacerbating the complexity of the design problem by introducing multiple local minimum points in design space. In addition, it would need a broad space with high dimensionality to obtain the ideal result, and expansion of design space could lead to more local minimum points, causing significant challenges to traditional optimization design methods. A Two-Stage Global–Local Constrained Optimization Method (TGLCOM) was proposed to address these issues. The parametric space was divided into a large-scale global space and a high-dimensional local space. A surrogate-based global constrained optimization method was applied in the large-scale global space, followed by a gradient-based algorithm in the high-dimensional local space to refine the design and obtain the global optima. The efficiency and robustness of the proposed TGLCOM were verified through the airfoil and flying wing layout aero/stealth design. The results indicated a minor conflict between the RCS drag and pitch moment performance. Moreover, the stealth design of the airfoil improved the stealth performance of the flying wing layout in both the yaw and pitch directions. Full article
(This article belongs to the Section Aeronautics)
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18 pages, 3493 KiB  
Article
Investigating the Effects of Leading- and Trailing-Edge Shapes of a Flapping Wing on Power Extraction Performance
by Suleiman Saleh and Chang-Hyun Sohn
Energies 2025, 18(11), 2749; https://doi.org/10.3390/en18112749 - 26 May 2025
Viewed by 375
Abstract
Flapping wings present a promising approach to harnessing energy from fluid flow by leveraging a synchronized pitching and heaving motion of the airfoil. The impact of modifying the leading and trailing edge shapes of a flapping wing on energy harvesting performance is investigated [...] Read more.
Flapping wings present a promising approach to harnessing energy from fluid flow by leveraging a synchronized pitching and heaving motion of the airfoil. The impact of modifying the leading and trailing edge shapes of a flapping wing on energy harvesting performance is investigated using sinusoidal pitching motion. The pitch angle varies between 80° and 90°. The wing thickness (T1) varies from 8% to 48% of the chord length, with a flat plate chord length of c = 1.0. A promising airfoil profile is achieved by increasing only the leading-edge thickness to 32% of the chord, significantly enhancing energy capture by improving the generation of pushing forces and power. The results show that a wing configuration with a semicircular leading edge and a rectangular trailing edge outperforms the baseline case (a rectangular flat plate) and all other configurations under the same conditions. This configuration shows a notable improvement in power output and efficiency at a pitch angle of 85° and a leading-edge thickness of 32% of the chord. The maximum power output (Cpt) represents a 16.73% increase over the baseline, while the maximum efficiency (η) reflects a 12.77% improvement. These findings highlight the superior energy extraction performance of the new configuration, emphasizing the dominant role of the leading edge in enhancing energy harvesters compared to the trailing edge. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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15 pages, 11215 KiB  
Article
Effects of Reduced Frequency on the Aerodynamic Characteristics of a Pitching Airfoil at Moderate Reynolds Numbers
by Teng Zhou, Huijing Cao and Ben Zhao
Aerospace 2025, 12(6), 457; https://doi.org/10.3390/aerospace12060457 - 23 May 2025
Viewed by 398
Abstract
Aerodynamic characteristics of a pitching NACA 0012 airfoil, including the load performance and flow field features, are studied using numerical simulations in this paper. Large Eddy Simulations (LESs) have been performed, and the chord-based Reynolds number is set to 6.6×104 [...] Read more.
Aerodynamic characteristics of a pitching NACA 0012 airfoil, including the load performance and flow field features, are studied using numerical simulations in this paper. Large Eddy Simulations (LESs) have been performed, and the chord-based Reynolds number is set to 6.6×104. Pitching frequency varies from 3 to 20 Hz, corresponding to a reduced frequency of 0.094–0.628 (k=πfpc/U, where fp is the pitching frequency, c is the chord length, and U refers to the incident flow speed). As the pitching frequency increases, the maximum lift coefficient achieved in one pitching cycle decreases, and the direction of the lift hysteresis loop changes as the pitching frequency exceeds a certain value, leading to a change in the lift of the sign at the zero-incidence moment, which is a result of the instantaneous flow patterns on the airfoil surface. As the pitching frequency increases, flow unsteadiness develops less in one pitching cycle, and the time duration in which the turbulence boundary layer can be detected in one pitching cycle shrinks. Additionally, for the pitching airfoil, combinations of the flow patterns on the upper and lower sides, such as laminar separation and the turbulent boundary layer, or laminar separation and the laminar separation bubble, were observed on the airfoil surface, and these were not detected on a static airfoil at the corresponding Reynolds number. This is considered an effect of the pitching motion that is in addition to the phase-lag effect. Full article
(This article belongs to the Special Issue Aerodynamics and Aeroacoustics of Unsteady Flow)
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16 pages, 4222 KiB  
Article
Numerical Simulation of Aerodynamic Characteristics of Trailing Edge Flaps for FFA-W3-241 Wind Turbine Airfoil
by Jiaxin Xu, Zhongyao Ji, Yihuang Zhang, Geye Yao, Yaoru Qian and Zhengzhi Wang
Machines 2025, 13(5), 366; https://doi.org/10.3390/machines13050366 - 29 Apr 2025
Viewed by 532
Abstract
The blades of wind turbines constitute key components for converting wind energy into electrical energy, and modifications to blade airfoil geometry can effectively enhance aerodynamic performance of wind turbine. The trailing edge flap enables load control on the blades through adjustments of its [...] Read more.
The blades of wind turbines constitute key components for converting wind energy into electrical energy, and modifications to blade airfoil geometry can effectively enhance aerodynamic performance of wind turbine. The trailing edge flap enables load control on the blades through adjustments of its motion and geometric parameters, thereby overcoming limitations inherent in conventional pitch control systems. However, current research primarily emphasizes isolated parametric effects on airfoil performance, with limited exploration of interactions between multiple design variables. This study adopts a numerical simulation approach based on the FFA-W3-241 airfoil of the DTU 10 MW. Geometric deformations are achieved by manipulating flap parameters, and the influence on airfoil aerodynamic performance is analyzed using computational fluid dynamics methods. Investigations are conducted into the effects of flap lengths and deflection angles on airfoil aerodynamic characteristics. The results show the existence of an optimal flap length and deflection angle combination. Specifically, when the flap length is 0.1c and the deflection angle is 10°, the lift-to-drag ratio demonstrates significant improvement under defined operational conditions. These findings offer practical guidance for optimizing wind turbine airfoil designs. Full article
(This article belongs to the Special Issue Cutting-Edge Applications of Wind Turbine Aerodynamics)
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21 pages, 7482 KiB  
Article
Numerical Analysis of the Aerodynamic Interactions in Tandem Flying Snake Airfoils
by Yuchen Gong, Jiacheng Guo, Alexander He, Ye Sun and Haibo Dong
Biomimetics 2025, 10(3), 174; https://doi.org/10.3390/biomimetics10030174 - 12 Mar 2025
Viewed by 767
Abstract
During gliding, flying snakes flatten their ribs to create an airfoil-like cross-section and adopt S-shape postures, allowing upstream body segments to generate wake structures that affect the aerodynamic performance of downstream segments. This study investigates these interactions using numerical simulations of two-dimensional snake [...] Read more.
During gliding, flying snakes flatten their ribs to create an airfoil-like cross-section and adopt S-shape postures, allowing upstream body segments to generate wake structures that affect the aerodynamic performance of downstream segments. This study investigates these interactions using numerical simulations of two-dimensional snake cross-sectional airfoils. By employing an immersed-boundary-method-based incompressible flow solver with tree topological local mesh refinement, various foil positions and movements were analyzed. The results show that aligning the downstream foil with the upstream foil reduces lift production by 86.5% and drag by 96.3%, leading to a 3.77-fold increase in the lift-to-drag ratio compared to a single airfoil. This improvement is attributed to the vortex–wedge interaction between the upstream vortex and the following foil’s leading edge (wedge), which enhances the gliding efficiency of the posterior body. Furthermore, integrating specific pitching motions with coordinated vortex shedding could further optimize its lift production. These findings provide valuable insights into the aerodynamics of tandem flying snake airfoils, offering guidance for configuring optimal body postures for improving gliding efficiency. Full article
(This article belongs to the Special Issue Bio-Inspired Propulsion and Fluid Mechanics)
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29 pages, 3075 KiB  
Article
Parametric Study of a Fully Passive Oscillating Foil on a Swinging Arm
by Dominic Cloutier, Mathieu Olivier and Guy Dumas
Energies 2025, 18(5), 1277; https://doi.org/10.3390/en18051277 - 5 Mar 2025
Cited by 1 | Viewed by 761
Abstract
A NACA 0015 airfoil is connected to a swinging arm by springs and dampers and is let loose in an incompressible and viscous flow at a Reynolds number of 3.9×106. The foil operates in a power-extracting regime and is [...] Read more.
A NACA 0015 airfoil is connected to a swinging arm by springs and dampers and is let loose in an incompressible and viscous flow at a Reynolds number of 3.9×106. The foil operates in a power-extracting regime and is free to pitch about a pivot that is itself swinging on a circular path; this contraption is called a fully passive oscillating-foil turbine on a swinging arm. This study explores the potential of four different foil configurations: with the swinging arm being either upstream or downstream of its pivot, and with or without the use of gears to control the equilibrium position of the foil with respect to the flow. The results show that the swinging arm concept offers similar performances, i.e., efficiency and power coefficient, as the railed turbine. Indeed, with arm lengths from 3 to 10 chords, efficiency values near 55% and power coefficients reaching 1.57 are obtained. Both the railed and the swinging arm turbines can operate under either a stall-flutter or a coupled-flutter instability. However, it is found that the geared models are the only ones suited when the driving mechanism is the coupled-flutter instability while both geared and gearless configurations are effective under the stall-flutter instability. Full article
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27 pages, 49547 KiB  
Article
Study of Airfoil Deflections for Unsteady Aerodynamics Optimization in Pitching Airfoils
by William Refling, Charles Fabijanic, Thomas Sprengeler, Yildirim Bora Suzen and Jordi Estevadeordal
Appl. Sci. 2025, 15(5), 2455; https://doi.org/10.3390/app15052455 - 25 Feb 2025
Viewed by 773
Abstract
Camber deflection concepts for a VR-12 rotorcraft airfoil were studied for the optimization of unsteady aerodynamics, including dynamic stall conditions and wing–wing interactions during pitching. The designs are based on deflections of the leading edge and trailing edge sections of the airfoil. The [...] Read more.
Camber deflection concepts for a VR-12 rotorcraft airfoil were studied for the optimization of unsteady aerodynamics, including dynamic stall conditions and wing–wing interactions during pitching. The designs are based on deflections of the leading edge and trailing edge sections of the airfoil. The deflection parameters were initially established using Computational Fluid Dynamics (CFD). Results from CFD and Particle Image Velocimetry (PIV) were generated for various leading and trailing edge deflection combinations for comparison of their performances. The conditions of this study are for a Reynolds number of 250,000 and pitching reduced frequency of 0.04, representing a medium regime of rotorcraft operations. Linear tandem tests were performed to simulate unsteady wing–wing interactions. The effects of the deflections are discussed and compared to the baseline. Significant benefits are observed, notably dynamic stall mitigation from the leading edge (LE) deflected wing for certain angles of attack and decrease in the separation regions. Overall, from the numerical simulations and the experimental data fields, the LE deflection provides about 10% improvement, followed by the combined LE&TE deflections (8%). It is also found that combining various deflections can provide a performance increase over drastically different areas of the range of angle of attack. Full article
(This article belongs to the Special Issue Application of Fluid Mechanics and Aerodynamics in Aerospace)
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20 pages, 6165 KiB  
Article
Micro UAVs with Fixed Wings: Design, Technological Solutions, and Tests
by Daniel Iorga, Constantin Georgescu, Sorin Constantinescu, George Ghiocel Ojoc, Alexandru Viorel Vasiliu, Mihai Constantinescu, Constantin Cristian Andrei and Lorena Deleanu
Aerospace 2024, 11(12), 977; https://doi.org/10.3390/aerospace11120977 - 27 Nov 2024
Cited by 1 | Viewed by 2245
Abstract
Considering the advantages of using expanded polystyrene (EPS) reinforced with adhesive tape made of glass fibers, this paper presents a design and technological solution for a functional drone of class C1, meaning a maximum take-off mass of 900 g, and tests validating the [...] Read more.
Considering the advantages of using expanded polystyrene (EPS) reinforced with adhesive tape made of glass fibers, this paper presents a design and technological solution for a functional drone of class C1, meaning a maximum take-off mass of 900 g, and tests validating the use of EPS for small UAVs under flight conditions. The selected profile was MH-49, which had a maximum chord thickness of 10.5%. This profile demonstrated a much lower coefficient of pitching moment than that of the NACA 63215 profile, giving this flying-wing UAV superior governability. This airfoil implies a geometry with greater attenuation of the trailing edge, and the design favors the placement of stress concentrators towards the trailing edge. Due to the use of fiberglass tape reinforcement technology, it is possible to address this profile, implying improved aerodynamic performance. The use of EPS in the disposable UAV industry may bring significant benefits, contributing to the development of high-performance, versatile, and low-cost UAVs, suitable for a wide range of tactical and logistic applications. This study presents the design, the fabrication, and testing of this drone, highlighting the advantages and possible challenges of the proposed solution. Full article
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11 pages, 6060 KiB  
Article
Investigation of Asymmetric Flow of a Slender Body with Low-Aspect Ratio Fins Having Large Deflection Angles
by Yonghong Li, Lin Zhang, Chuan Gao, Jilong Zhu and Bin Dong
Aerospace 2024, 11(10), 835; https://doi.org/10.3390/aerospace11100835 - 10 Oct 2024
Cited by 4 | Viewed by 1087
Abstract
To understand the asymmetric flow of a slender body with low-aspect ratio fins, a wind tunnel experiment was carried out, and the asymmetric flow was observed when the pair of fins had a symmetric deflection angle of 30° at a small angle of [...] Read more.
To understand the asymmetric flow of a slender body with low-aspect ratio fins, a wind tunnel experiment was carried out, and the asymmetric flow was observed when the pair of fins had a symmetric deflection angle of 30° at a small angle of attack and zero sideslip angle at transonic speeds. The unsteady characteristics of flow around the moving fins, especially for the evolution of the asymmetric flow, was carefully numerically investigated via the RANS method. To verify the numerical method, the experimental steady wind tunnel data of the NACA 0012 airfoil with sinusoidal pitching motion were adopted. A hysteresis loop exists as a function of the deflection angle during the upstroke and downstroke motions. The side force is periodic due to the asymmetric flow peaks at the downstroke and their peak value appeared at around δz = 25°, which was independent of the deflection frequency. As the deflection frequency increased, the asymmetric flow formed at a higher deflection angle during the upstroke motion, but decayed at a lower deflection angle during the downstroke motion, resulting in a more significant unsteady hysteresis effect. Full article
(This article belongs to the Section Aeronautics)
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19 pages, 8455 KiB  
Article
Analysis of the Transonic Buffet Characteristics of Stationary and Pitching OAT15A Airfoil
by Xueyuan Nie, Guannan Zheng, Lianyi Wei, Chengde Huang, Guowei Yang and Zhanling Ji
Appl. Sci. 2024, 14(16), 7149; https://doi.org/10.3390/app14167149 - 14 Aug 2024
Cited by 1 | Viewed by 1287
Abstract
Transonic buffet flow is a classical complex and unstable flow that has a negative effect on aircraft fly safety. Therefore, it is crucial to study the unsteady characteristics of buffet flow. The numerical analysis method is very useful in achieving the aforementioned goal. [...] Read more.
Transonic buffet flow is a classical complex and unstable flow that has a negative effect on aircraft fly safety. Therefore, it is crucial to study the unsteady characteristics of buffet flow. The numerical analysis method is very useful in achieving the aforementioned goal. In this paper, focused on the typical supercritical airfoil OAT15A in fixed and pitching conditions, unsteady Reynolds averaged Navier–Stokes (URANS) closed with the sst-kω turbulence mode, coupled with the structure dynamical equation, is utilized to investigate the transonic buffet flow. Firstly, from the perspective of coherent flow structure, flow velocity divergence snapshots constructed from unsteady flow solutions are used to analyze the feature of transonic buffets in the two cases mentioned. Then, DMD modes are extracted by the dynamic mode decomposition technique from the velocity snapshots and adopted to analyze the flow modes of the two distinct flow fields. The numerical simulation results show that, in the fixed case, the regular motion feature of the buffet is present, the shock oscillation is closely related to the vortex structure, and the durations of rearward and forward movements of the shock are both equal to half of the buffet period. In the pitching case, the duration of the rearward motion of the primary shock is approximately five eighths of one buffet period, and the secondary shock appears with the primary one moving downstream, and they interact with each other. The region of the shock movement is larger than that of the fixed case, and there is chaotic flow rather than periodic flow in its wake. Structural elastic oscillation changes the characteristics of the aerodynamic response, which is solely affected by the frequency of the pitching oscillation. Full article
(This article belongs to the Section Aerospace Science and Engineering)
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16 pages, 5933 KiB  
Article
Wind Tunnel Investigation of the Icing of a Drone Rotor in Forward Flight
by Derek Harvey, Eric Villeneuve, Mathieu Béland and Maxime Lapalme
Drones 2024, 8(8), 380; https://doi.org/10.3390/drones8080380 - 7 Aug 2024
Cited by 2 | Viewed by 2484
Abstract
The Bell Textron APT70 is a UAV concept developed for last mile delivery and other usual applications. It performs vertical takeoff and transition into aircraft mode for forward flight. It includes four rotor each with four rotating blades. A test campaign has been [...] Read more.
The Bell Textron APT70 is a UAV concept developed for last mile delivery and other usual applications. It performs vertical takeoff and transition into aircraft mode for forward flight. It includes four rotor each with four rotating blades. A test campaign has been performed to study the effects of ice accretion on rotor performance through a parametric study of different parameters, namely MVD, LWC, rotor speed, and pitch angle. This paper presents the last experimentations of this campaign for the drone rotor operating in forward flight under simulated icing conditions in a refrigerated, closed-loop wind tunnel. Results demonstrated that the different parameters studied greatly impacted the collection efficiency of the blades and thus, the resulting ice accretion. Smaller droplets were more easily influenced by the streamlines around the rotating blades, resulting in less droplets impacting the surface and thus slower ice accumulations. Higher rotation speeds and pitch angles generated more energetic streamlines, which again transported more droplets around the airfoils instead of them impacting on the surface, which also led to slower accumulation. Slower ice accumulation resulted in slower thrust losses, since the loss in performances can be directly linked to the amount of ice accreted. This research has not only allowed the obtainment of very insightful results on the effect of each test parameter on the ice accumulation, but it has also conducted the development of a unique test bench for UAV propellers. The new circular test sections along with the new instrumentation installed in and around the tunnel will allow the laboratory to be able to generate icing on various type of UAV in forward flight under representative atmospheric conditions. Full article
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