This study presents the experimental design and validation of a Straight Spar structure intended for aeroelastic flutter testing, particularly for fixedwing UAV applications. The main objective is to develop a spar that exhibits flutter onset within a target velocity range of 20-25 m/s. The research employs fully experimental methods, including vibration testing for modal analysis and wind tunnel testing to observe flutter behavior. Comparative analysis with simulation results was conducted for validation. The designed spar successfully demonstrated flutter at 20 m/s, with only a 0.32 m/s deviation from simulation predictions. Furthermore, both experimental and simulation methods identified the bending and torsion mode shapes at nearly identical frequencies, confirming strong agreement and model validity. These findings affirm the suitability of the proposed spar design for UAVs operating within the specified flight speed range and lay the foundation for future studies on aeroelastic energy harvesting.
Due to the presence of additional structures, complex dynamic and static interference phenomena frequently occur within the internal flow of the fan. This study employs large eddy simulation (LES) combined with hybrid calculation methods to investigate the aerodynamic noise characteristics of a single-stage axial flow fan. Experimental research on the flow field and noise was conducted using a fan test bench. The noise flow modes associated with additional mechanisms, such as junction boxes and support plates, were analyzed using dynamic mode decomposition (DMD). The results demonstrate that the hybrid calculation method based on LES accurately predicts the aerodynamic characteristics and aerodynamic noise of a single-stage axial flow fan. The agreement between the predicted single-tone noise and broadband noise is excellent. The rotor wake was extracted in the planes at X =-0.15, capturing the dynamic and static interference effects. It was found that the presence of additional structures resulted in unidentified frequency components of 92 Hz and 146 Hz. Further analysis revealed complex wake-structure interference effects at 1BPF and 2BPF on the X = 0 and X = 0.2 planes. The vortex shedding at the tail of the support plate was identified as the source of the 92 Hz noise component, while the interference effect between the stator wake and the junction box cylinder was identified as the aerodynamic sound source of the 146 Hz noise component.
The hypersonic inlet/isolator is a critical component of scramjet engines, where complex shock wave-boundary layer interaction (SWBLI) occur, significantly influencing overall engine performance. This study employs numerical simulations using Fluent with the k-omega Shear Stress Transport (SST) turbulence model to systematically investigate the impact of varying incoming boundary layer thicknesses on inlet/isolator performance. By extending the upstream flat plate length, boundary layers with relative thicknesses (delta/h) ranging from approximately 0.17 to 1.18 were generated. Performance parameters, including static pressure ratio, static temperature ratio, outlet average Mach number, and total pressure recovery coefficient, were analyzed for external compression angles of 0 degrees and 10 degrees at a freestream Mach number of 5. The results demonstrate that increasing the boundary layer thickness leads to an upstream shift of the shock train within the isolator, intensifies SWBLI, and promotes flow separation. Consequently, the total pressure recovery coefficient decreases, indicating a deterioration in inlet/isolator performance. A critical relative thickness (delta/h approximate to 3/5) was identified, beyond which the total pressure recovery coefficient drops significantly for the 0 degrees compression angle. Notably, for the 10 degrees compression angle, the flow field at the isolator outlet becomes more uniform under varying boundary layer thicknesses, resulting in smaller variations in the total pressure recovery coefficient. This enhanced stability suggests that the presence of a compression angle improves the inlet/isolator's resistance to disturbances, which is beneficial for downstream combustion processes. These findings provide valuable insights for the design and optimization of robust hypersonic inlet/isolator systems.
The combustion characteristics of hydrocarbon fuels after shock wave interaction remain insufficiently understood, despite their continued widespread use in engineering applications. This article studied the numerical results solved by Navier-Stokes equation with chemical source term, focusing on the differences of flow pattern of reactive shock (Ma = 1.22) interacting with hydrocarbon cylinder (two-dimensional configuration) or bubble (threedimensional configuration) to reflect the influence of three-dimensional effect on Hydrocarbon cylinder/bubble's morphology and dynamics. Results showed that the flow field of cylinder and bubble has both similarities and differences. The similarities are that the leading edge of cylinder and bubble both roll up due to baroclinic vorticity while the interface has higher temperature and fuller combustion. Analysis of the flow structure evolution reveals three typical stages in the process. As a result of the dilation effect of chemical heat release, cylinder and bubble both have a nonlinear increase in the streamwise direction. The differences are that the main vortex of the cylinder expands continuously without obvious tailing, while in the threedimensional configuration, the region of the main vortex shows limited increase at later stage. There is a trailing lobe separating the main vortex of bubble from its tailing, showing the limiting formation of the compressible reacting vortex ring. Further considering the location of different portions of cylinder and bubble quantitatively, it can be modeled that bubble has a higher advancing velocity and kinematic velocity of vortical structure than the cylinder does due to the self-induced velocity from Biot-Savart law, vortex-wake decoupling and enhanced baroclinicity.
Drones are increasingly employed across various domains where performance, safety, and energy efficiency are essential. As the primary thrust-generating element, the propeller critically influences overall aerodynamic performance. This study investigates a non-uniform leading-edge (LE) tubercle design, inspired by the humpback whale flipper, to enhance UAV-scale propeller efficiency at low Reynolds numbers. Unlike conventional uniform tubercle configurations, the present work introduces variable amplitude and wavelength distributions along the blade span. The non-uniform configuration modifies local flow curvature and vortex strength, promoting smoother pressure gradients, delaying flow separation, and maintaining higher momentum near the blade surface. Computational Fluid Dynamics (CFD) simulations conducted in ANSYS Fluent compare the aerodynamic performance of the tubercle-modified propeller with a pla in baseline across a range of advance ratios (J = 0.1-0.6) and rotational speeds (2000-10,000 RPM). Results indicate that the tubercle propeller demonstrates improved aerodynamic performance, particularly at higher RPM, with an average increase of 10-18% in thrust coefficient (KT) and 8-15% in power coefficient (KP), leading to notable efficiency gains. The findings confirm that incorporating non-uniform LE tubercles enhances flow stability, reduces drag, and improves thrust generation. These advantages are more pronounced at higher advance ratios, highlighting the design's adaptability to diverse opera ting conditions. The study establishes a foundation for future experimental validation and optimization of biomimetic propeller geometries for UAV applications.
This paper presents the design, fabrication and experimental validation of an E-shaped microstrip patch antenna (MPA) intended for C-band communication applications. The antenna is implemented on a Rogers RT/duroid 5880 substrate and fabricated using a fabrication-aware hybrid process combining laser engraving and photolithography to achieve high dimensional accuracy and repeatability. The E-shaped configuration is employed to overcome the bandwidth limitations of conventional rectangular microstrip patches while maintaining a simple single-layer planar structure. The antenna design was optimised using CST Studio Suite and subsequently characterised experimentally using a calibrated vector network analyser (VNA) and planar near-field measurements in an anechoic chamber. Simulation results predict resonance at 6.02 GHz with a return loss of-21.4 dB and a VSWR of 1.19, while experimental measurements indicate resonance at 5.80 GHz with a return loss of-11.8 dB and a VSWR of 1.69, showing good agreement between simulation and measurement. Radiation measurements confirm stable directional characteristics, a measured gain of 8.21 dBi, and a radiation efficiency of 55.96% at 5.8 GHz. The results demonstrate that the proposed E-shaped microstrip patch antenna achieves reliable C-band performance with consistent impedance matching, radiation efficiency, and gain, making it suitable for aerospace and satellite communication systems where manufacturability and experimental validation are critical considerations.
Fire safety remains a critical challenge in modern aviation due to the increasing use of composite materials, high-power electrical systems, and lithium-ion batteries. This review provides a comprehensive overview of advances in aircraft fire safety from 2000-2025, covering fire-resistant materials, cabin and cargo fire behavior, detection technologies, suppression systems, and regulatory developments. The performance of polymer composites, interior materials, and fuel tank protection systems is discussed, with emphasis on heat release, smoke toxicity, and structural integrity under fire conditions. Recent progress in smoke, gas, and temperature-based detection systems, as well as emerging AI-assisted monitoring, is reviewed alongside current limitations such as false alarms and delayed detection. The transition from Halon-based suppression to environmentally acceptable alternatives and the growing challenge of lithium-ion battery fires are also examined. The review highlights the shift towards performance-based regulations and integrated safety management systems. Overall, the paper emphasizes the need for coordinated material, system, and regulatory innovations to enhance fire safety in next-generation aircraft.
This paper presents the aero-structural design, analysis, and validation of a small-scale modular RC aircraft developed using a civil aerospace systems engineering framework inspired by ARP4754A. The ARP4754A Vmodel lifecycle-linking systematic requirement decomposition to verification and validation-is adapted to ensure traceability, rigor, and consistency throughout the aircraft development process. The platform was developed using explicit requirement flow-down (Tier-1 to Tier-3), trade-study-driven configuration selection, multi-domain simulation, and ground and flight testing, addressing the lack of structured systems-engineering practices commonly observed in small-scale modular RC aircraft development. A high-wing CH10 monoplane configuration with a carbon-fiber-reinforced balsa spar was selected using Pugh matrices within a multidisciplinary trade framework. Aerodynamic characteristics were evaluated using XFLR5 and AVL, structural integrity was assessed through analytical beam theory and finite element analysis, and modal behavior was examined using MATLAB and ANSYS to assess dynamic response and flutter margins. Manufacturing fidelity was supported through geometric dimensioning and tolerancing (GD&T). Quantitative validation demonstrated stable trimmed flight at approximately 2 degrees angle of attack, a thrust-to-weight ratio near unity, and maximum wing stresses within 95% of conservative carbon-fiber allowable limits under limit-load conditions. The results demonstrate that an ARP4754A-aligned, model-based systems engineering approach can be effectively applied to the aero-structural development of small-scale modular unmanned aircraft, yielding verifiable performance, conservative safety margins, and traceable design decisions.
To address the challenges of high volatility in aviation spare parts demand data and the insufficient accuracy of traditional grey forecasting models, this paper proposes an improved grey rolling prediction model (AMPSO-AGRMO(1,1)) that integrates afull-information buffering operator and adaptive multi-strategy particle swarm optimization (AMPSO). First, a full-information weak buffering operator is constructed to correct the original data sequence. By dynamically adjusting the sequence weight parameter (lambda) and the effect adjustment weight parameter (gamma), the operator effectively eliminates abnormal fluctuations caused by typical aviation support events- such as sudden failures and batch replacements-while preserving the core demand trends determined by support strategies like periodic overhaul and condition-based maintenance. Second, an improved particle swarm optimization algorithm is employed to dynamically optimize the parameters of the buffering operator. Its adaptive adjustment mechanism simulates the decision-making process of support personnel integrating historical experience with current optimal strategies, thereby overcoming the tendency of traditional PSO algorithms to converge to local optima and enhancing the model's adaptability to the nonlinear and intermittent characteristics of aviation spare parts demand. Finally, by combining a rolling modeling mechanism, the optimized buffering operator is integrated with the improved grey model to establish a forecasting model that possesses both global search capability and convergence precision. Using 16 periods of actual demand data for maintenance spare parts of a certain type of aircraft engine's highpressure turbine blades as a case study, comparative analysis with traditional GM(1,1), rolling GM(1,1), LSTM, ARIMA, and SVR models shows that the AMPSO-AGRMO(1,1) model achieves a mean absolute percentage error (MAPE) of 3.05%, significantly outperforming the comparison models. Sensitivity analysis indicates that the model is insensitive to parameter perturbations (MAPE variation rate < 7%), verifying its robustness. This research provides a novel technical approach closely aligned with support mechanisms for forecasting spare parts of complex equipment, offering significant engineering application value for enhancing the efficiency of aviation equipment maintenance support and optimizing resource allocation.
The accuracy of predicting the surface quantities in high-speed rarefied flows depends on the nonequilibrium conditions. Recently, a newly developed first-order slip condition incorporating the near-wall distance was proposed, yielding accurate predictions of slip velocity in hypersonic flows. The present study proposes a second-order slip condition, incorporating that distance, to enhance the aforementioned first-order slip condition. It is designed to work with the Navier-Stokes-Fourier equations through the "rhoCentralFoam" solver in OpenFOAM. Aerodynamic configurations, such as the wedge, the flat plate with a sharp leading edge, and the vertical plate, are selected to validate the proposed second-order slip condition. The working fluid in the current study is nitrogen gas. It can be concluded that the proposed second-order slip condition generally predicts slip velocities more accurately than the newly developed first-order slip condition and agrees well with the results obtained from Direct Simulation Monte Carlo simulations.
The Common Research Model (CRM) wing is a widely used reference model in aerodynamics research for aircraft design. This study investigates the aerodynamic performance of a scaled-down CRM wing at Mach 0.85 under transonic flow conditions using ANSYS Fluent 2023. This paper presents a novel numerical investigation that systematically assesses the influence of grid size on the numerical results. Additionally, the performance of six different turbulence models is comparatively analysed. The K-epsilon model showed a validation error of 2.7%, indicating accurate prediction of drag. The findings support the transonic flow analysis of the CRM wing. This research provides useful aerodynamic data for researchers working in nacelle flow analysis and geometry optimization.
A solid rocket is a type of propulsion system that uses a solid mixture of fuel and oxidizer to generate thrust. It is widely recognized for its simplicity, reliability, and high energy efficiency in aerospace and defense applications. Aluminum powder, a commonly used metallic fuel, provides high combustion energy but faces challenges such as oxide shell formation and particle agglomeration, which can prevent complete combustion. To overcome these limitations, researchers have investigated embedding of aluminum and copper metal wires to enhance reactivity and improve combustion performance. The experimental studies include burn rate under ambient environment, density measurement, calorific value and flame temperature analysis. The burn rate of propellant samples embedded with high thickness aluminum and copper metal wires increased by 49.18%, and 52.40%, respectively. The heat of combustion, density, and flame temperature also increased significantly with the increase in metal wire thickness. These findings highlight a trade-off between performance enhancement and combustion efficiency at larger wire dimensions, suggesting that an optimal wire thickness is crucial for maximizing propellant performance.
This study presents the design and implementation of a flexible testing setup for a basic landing gear model integrated with electro-hydraulic systems. The setup enables thorough assessment of landing gear operations critical to takeoff and landing. A key contribution is the construction of a scaled-down, slider-crank-inspired model to demonstrate extension and retraction, serving both rigorous testing and educational purposes. The model bridges theory and practice, providing hands-on experience for students and professionals. The novelty of this work lies not in proposing a new landing gear configuration, but in developing an experimentally validated, modular, and scalable integrated design framework that combines a slider-crank mechanism with electro-hydraulic actuation. The setup supports systematic parametric studies through variation of link dimensions, actuation parameters, and operating angles, enabling evaluation under diverse landing scenarios, including emergency and high-impact conditions. By integrating static analysis, kinematic simulation, and experimental validation, the platform serves as a practical foundation for educational and early-stage aerospace design studies, while remaining readily extendable to advanced testing scenarios such as dynamic response evaluation, control strategy development, and integration with sensing and monitoring systems. In aeronautical engineering, landing gear is one of the most critical aircraft systems, requiring thorough evaluation to ensure safety performance and reliable operation. As modern aircrafts evolve to adopt electro-hydraulic actuation and greater automation, there is a growing need for small-scale setups that represent these technologies while remaining suitable for academic use and early-stage research. Overall, this research advances aeronautical engineering by offering a robust platform for testing and demonstrating landing gear technologies, enhancing accuracy, reliability, and the development of safer, more efficient aircraft operations, while emphasizing the value of being flexible to integrate advanced technologies in both education and industry. Building on earlier automation-focused studies by the authors, this work emphasizes an experimentally validated electrohydraulic and mechanical integration framework suitable for both educational and early-stage aerospace research.
An igniter in rockets is a device that initiates the combustion of the rocket propellant to start thrust generation. A bag-type pyrotechnic igniter is a compact, lightweight device used in solid rocket motors. It contains hightemperature burning powders or pellets in a combustible bag, ensuring uniform and reliable ignition through concentrated heat release. While known for simplicity and robustness, detailed studies on igniter compositions are limited. This study evaluates six pyrotechnic igniter compositions using magnesium, aluminium, and potassium nitrate, with carbon black and ferric oxide as additives. Experimental calorific value measurements and thermogravimetric analysis (TGA) were conducted. Results show that aluminium-based igniters generally provide higher energy output than magnesium-based ones. However, adding Fe2O3 to Mg-KNO3 significantly boosts its calorific value, even surpassing pure aluminium-based compositions. Carbon black slightly enhances or maintains energy output but mainly extends combustion by acting as extra fuel. Overall, Fe2O3 proves to be an effective additive for increasing ignition energy and reactivity, thus demonstrating the properties of an effective igniter.
The objective of the present work is to model elliptical notches reinforced with power law based functionally graded material layer (PFGML) to analyse the stress distribution near the notches, within the PFGML and the stress concentration factor (SCF). The PFGML parameters are also optimized to smoothen the stress distribution as well as the SCF. To model the current problem, a 2D rectangular panel is considered with two semielliptical notches on both side of the panel, surrounded by the PFGML and the panel is subjected to uniaxial tensile and bending loads. For numerical analysis, the problem is modelled using the extended finite element method (XFEM), and the computer code was developed in MATLAB. The prepared computer code was first validated with existing results from the literature for elliptical notches in homogeneous material panels, as well as with experimental results for PFGML around circular holes. The validated computer code has been used to analyze stresses near elliptical notches. It has been observed that by applying PFGML, the stress distribution becomes smoother and the SCF is significantly reduced. The interaction effect of PFGMLs is found to be more influential in tensile loading and can be minimized by selecting a smaller PFGML coefficient n. The PFGML coefficient 0.75 is found to be suitable for both tensile and inplane bending loads. A thin PFGML is observed to be suitable for elliptical notches, whereas circular notches require a thicker PFGML.
This study analyzes turning flights (kinematics) of bees flying in a curved tunnel, and compares the turning characteristics observed in a curved tunnel with those observed in a semi-outdoor environment called a 'bee cloud', in the core as well as the outer periphery of the cloud environment. A high-speed synchronized stereo camera setup was used to capture and investigate the turning flight characteristics of bees in this study. To convert the captured video data into meaningful information, one has to determine the 3D location of each bee in each video frame. To achieve this, we used our custom-built tracking software "Bee-Trace", to track and reconstruct the trajectories of the bees in three dimensions. The analysis and interpretation of data collected in the three different environments are discussed in this paper. The results indicate that bees turning in the tunnel and in the periphery of the bee cloud tend to hold their flight speed constant while undergoing substantial changes in the curvature and centrifugal force. These turns are very different from those of bees flying in the central core of the cloud, where the centrifugal force is held constant. The comparative analysis performed in this study provides a more complete understanding on how turning flight of insects differs in three different environments, eventually enabling us to apply the deduced flight principles of insects to aerial vehicles traversing similar conditions.
Thermal runaway (TR) in lithium-ion (Li-ion) batteries is a critical safety issue for space use due to limited cooling, vacuum, and thermal cycling. Predictive modelling is vital for robust battery design. This study used ANSYS Fluent's Conjugate Heat Transfer (CHT) model with a four-equation abuse source term to simulate two 4-cell 18650 Li-ion packs under near-space conditions. A bare-cell pack served as the baseline; the second includes an aluminium interstitial to boost lateral heat conduction. Both packs faced a 40 W heat flux on a trigger cell and a 10 A discharge at full charge. The aluminium-interstitial pack delayed TR initiation in the trigger cell from 202 s to 1186 s and raises the critical temperature (Tc) from 447 K to 483 K. Subsequent cells showed progressive Tc improvements of 11-13%, with initiation times extended up to 487%. Temperature contour analysis revealed more uniform thermal fields and reduced hotspot formation with aluminium interstitials. Model validation showed under 5.1% error versus single-cell experiments, confirming predictive accuracy. These results demonstrated that aluminium interstitials effectively mitigate TR propagation risk in space-grade Li-ion batteries and provide design guidance for safer energy storage systems.
Stabilizing flame in the scramjet engine is crucial for the effective operation of the propulsion system in a supersonic air-breathing aircraft. Here, a novel strut design involving dual rocket strut with semicircular trailing edge is proposed for flame stabilization to improve the combustion characteristics of a scramjet. The proposed novel strut is an improved variant of the traditional wedge strut, featuring a leading edge, a stride and a rear wedge with enlarged angles, along with a semicircular trailing edge (T.E.) at the strut base. The two-dimensional steady Reynolds Averaged Navier-Stokes equations are solved using SST k-omega for turbulence modelling and single step reaction finite rate eddy dissipation approach for combustion modelling. The grid independence study showed that the medium grid offers the same accuracy as the fine grid. The simulated wall pressure and the density contours with the traditional DLR scramjet combustor displayed shock structures and flow patterns consistent with the experimental data, validating the adopted computational approach. The impact of the proposed strut on the mixing of the fuel and air thus on the combustion performance of the scramjet combustor is assessed by investigating the recirculation zone and evaluating the mixing efficiency. The findings revealed that the novel dual rocket strut with semicircular T.E. design exhibits two-pairs of recirculation zone, one around each fuel injection point with higher magnitudes of z-component of vorticity, implying stronger recirculation region and higher mixing. Thus, the novel strut shows 30% increase in mixing efficiency as compared to the single wedge strut.
The aim of the present work is to identify an appropriate machine-learning-based model for estimating an aircraft's stability and control derivatives (also referred to as aerodynamic parameters) using flight data. Parameter estimation is performed by minimizing the error between the simulated response and the response predicted by the trained machine-learning model. Machine-learning-based models, namely the Feed Forward Neural Network (FFNN), Cascade Forward Neural Network (CFNN), and Elman Forward Neural Network (EFNN), are employed in conjunction with Levenberg-Marquardt (LM) and Bayesian Regularization (BR) training algorithms. These models are trained using simulated, time-dependent aircraft longitudinal motion and control variables as inputs, with the corresponding force and moment coefficients as outputs. The trained models are subsequently tested using modified input sets of motion and control variables to generate predicted force and moment coefficients. Aerodynamic parameters are then estimated from these predicted coefficients using the Delta method. To assess robustness under realistic operating conditions, Gaussian noise of varying intensity is added to the simulated data. The performance of all ML-based models is validated by comparing the estimated parameters with their true values using mean square error metrics and graphical comparisons between simulated and estimated responses. Based on the results, the CFNN model trained with Bayesian Regularization demonstrates superior accuracy and robustness. The proposed approach is therefore suitable for application to both simulated and real flight-test data of aircraft, UAVs, and missiles for aerodynamic parameter estimation.
This study comprehensively investigates the aerodynamic performance of five distinct airfoils-e339-il, Falcon, MH60-il, NACA 2412, and TsAGI-12-il -integrated into Blended Wing Body (BWB) Unmanned Aerial Vehicle (UAV) designs. Through comparative analyses, we examined key aerodynamic parameters including lift, drag coefficient, lift-to-drag ratio, endurance curve, and pitching moment coefficient as a function of the angle of attack. Our findings indicate that for high angles of attack, the Falcon and TsAGI-12-il airfoils demonstrate superior aerodynamic efficiency, while the MH60-il and TsAGI-12-il achieve the highest lift-to-drag ratios (28.85 and 28.65 respectively), crucial for maximizing range. For optimal endurance, the Eppler 339 and NACA 2412 perform well, though the MH60-il excels at a 5degree angle of attack. Furthermore, the MH60-il, TsAGI-12-il, and NACA 2412 airfoils consistently exhibit superior longitudinal stability. The Eppler 339, conversely, shows significantly higher drag. This research provides critical data for the advanced design and optimization of BWB aerial platforms, highlighting the MH60-il as a strong candidate due to its balanced performance across efficiency, endurance, and stability at typical operational speeds. These superiorities were observed in maximum range, minimum descent rate, and maximum endurance, providing crucial data for the advanced design and optimization of next-generation BWB aerial platforms.
