Search Results (926)

Background/Objectives: This investigation aims to assess the potential for repurposing nitazoxanide (NIT) as a treatment for COVID-19. NIT was loaded into terpene-enriched chondrosomes (TECs) to assess its anti-hCoV-19 activity through pulmonary delivery. Methods: NIT-TECs were then fabricated utilizing the ethanol injection method. Using a D-optimal design, the effects of factors on entrapment efficiency (EE%), particle size (PS), and zeta potential (ZP) were determined, and the optimal formulation was selected. Results: The optimum TEC exhibited an EE% of 98.87 ± 0.69, a PS of 129.43 ± 5.43 nm, a polydispersity index (PDI) of 0.433 ± 0.022, and a ZP of −25.99 ± 0.99 mV. The optimum TEC was lyophilized to attain a dry powder. Further, the differential scanning calorimetry test confirmed that NIT was transformed from crystalline to amorphous form inside the optimum TEC. In addition, the mucoadhesion test confirmed the ability of the optimum TECs to adhere to pulmonary tissues. Additionally, NIT binding to the active site of SARS-CoV-2 enzymes was investigated using in silico analysis. When compared to NIT, the aerodynamic characteristics of the lyophilized optimum TECs employing the cascade impactor showed superior residence in the lungs. Conclusions: These findings suggest that loading NIT into TECs enhanced its antiviral activity, as indicated by the in vitro cytotoxicity study. Overall, the results point to NIT-loaded TECs as a potentially effective pulmonary delivery system for COVID-19 treatment. Full article

This paper presents the development of a novel morphing wing prototype with three camber-twist morphing flaps. Reflexed airfoil morphing is achieved by means of two chordwise degrees-of-freedom, thereby decoupling lift from the aerodynamic moment with respect to the aerodynamic centre. The prototype wing design is characterised by a novel morphing flap concept and driven by the boundary conditions pertinent to the wind tunnel testing facilities and the choice of research questions. The flaps’ spanwise ends are adapted to represent a seamless and a discontinuous transition between adjacent flaps. Linear electric motors induce the morphing shapes, equipped with load cells on their respective push rods, for actuator force measurement. Pressure taps are included to measure the pressure distribution along the wing section. Upon manufacturing, preliminary static test results validate the wing’s morphing functionality. The morphing trailing edge demonstrates a range of camber morphing and twist morphing shapes, as well as the ability to support asymmetric morphing between adjacent flaps. Full article

Flapping-wing drones (FWDs), owing to their compact size and operation in cluttered and unsteady airflow environments, encounter significant aerodynamic and stability challenges. Studies of avian flight reveal that falcons and other raptors actively deflect their covert feathers to mitigate gusts and maintain stable flight. Drawing inspiration from this mechanism, this study presents a peregrine falcon-inspired Active Flow Control Unit (AFCU) integrated with a Deep Deterministic Policy Gradient (DDPG)-based deep reinforcement learning (DRL) controller for real-time disturbance attenuation. The AFCU employs mechanical covert feathers (MCFs) that actuate to dissipate gust loads during high wind conditions. A reduced-order bond graph model that encapsulates the nonlinear interaction between the primary wing and the feather-based active flow control surfaces is created which is used as a dynamic training environment for the DDPG agent. Utilizing closed-loop interactions, the successfully obtained learned policy produces optimal actuator forces to reduce feather-displacement error and aerodynamic load variations. The designed controller stabilizes the internally unstable open-loop AFCU, attaining near-zero steady-state error and settling times under 1.6 s for gust magnitudes ranging from 12.5 to 20 m/s. Simulations further illustrate a reduction of up to 50% in gust-induced loads compared to traditional approaches. This integration of bio-inspired design with learning-based active flow control offers a viable avenue for the development of highly adaptive and gust-resilient flapping-wing aerial systems. Full article

Previous studies and current wind-load standards for low-aspect-ratio circular structures primarily consider external pressure and insufficiently address the combined effects of roof openings, internal–external-pressure interaction, and surface roughness. To overcome these limitations, this study investigates the net-pressure characteristics of such structures through wind-tunnel experiments conducted for two aspect ratios and four levels of surface roughness. The vertical variation in net pressure and its implications for wind-load estimation are systematically examined. For smooth surfaces, the net-pressure distribution exhibits pronounced height dependence due to the free-end effect. This dependence diminishes as surface roughness increases, indicating a significant modification of the flow structure around the cylinder. Neglecting this height-dependent behavior leads to substantial inaccuracies in drag-coefficient estimation. Comparisons with existing standards reveal that the drag coefficients specified in AS/NZS 1170.2 and AIJ-RLB overestimate values for smooth surfaces by up to 38.7% and 21.5%, respectively, whereas the AIJ-RLB provisions underestimate values for rough surfaces by approximately 4.7%. To improve predictive accuracy, a simplified model for the circumferential distribution of mean net-pressure coefficients is developed. The proposed model incorporates height-dependent aerodynamic parameters and demonstrates strong agreement with experimental data, with a maximum relative error below 8.6%. This model provides a practical reference for more reliable wind-load estimation in the structural design of low-aspect-ratio circular structures with roof openings. Full article

Understanding the unsteady aerodynamic behavior of quadrotor unmanned aerial vehicle (UAV) is critical for improving flight stability, control, and performance, particularly in complex operational environments. In closely spaced multirotor configurations, coherent tip vortices shed from each blade convect downstream and form helical vortex streets that interact with subsequent blades and neighboring rotors. These interactions induce rapid fluctuations in local inflow velocity and effective angle of attack, resulting in transient lift variations, increased vibratory loads, and elevated acoustic emissions. This study presents a comprehensive computational investigation of quadrotor rotor interactions and wake dynamics using a large-eddy simulation (LES). Detailed analyses reveal that the formation and evolution of tip vortices and blade–vortex interaction phenomena significantly influence lift fluctuations and aerodynamic loading. The simulations capture transient wake structures and their effects on neighboring rotors, highlighting unsteady aerodynamic mechanisms that are not adequately predicted by conventional RANS or URANS approaches. Parametric studies examining vortex-street offset distance demonstrate the sensitivity of wake-induced instabilities to design and operational parameters. The results provide new physical insights into multirotor wake dynamics and establish the LES as a predictive framework for quantifying unsteady aerodynamic loading in quadrotor drones. The findings provide insights into the complex flow physics of multirotor systems, offering guidance for more accurate modeling, rotorcraft design optimization, and the development of control strategies that mitigate adverse unsteady aerodynamic effects. This study provides new insights into rotor–vortex-street interactions, with applications to multirotor UAVs, by isolating multi-vortex coupling effects and quantifying the influence of horizontal vortex spacing on unsteady aerodynamic loading, complementing existing high-fidelity LES research. Full article

To alleviate the adverse effects of the flow-field structure caused by interstage sealing structures on the aerodynamic characteristics of compressor cascades, a blade-root through-slot structure was designed in this study. The structure links the pressure surface to the suction surface of the blade. Numerical simulation techniques were utilized to investigate the process. In this process, the through-slot structure enhances corner separation across varying jet positions, jet heights, and jet widths. The results indicate that the high-speed fluid ejected by the through-slot configuration can suppress the accumulation of low-energy fluid at the suction root. It can also alleviate blockages in the cascade passage and reduce the range of separation vortices and recirculation zones on the suction side. Consequently, the flow loss due to separation is reduced. As the through-slot jet progresses from the blade leading edge to the trailing edge, its restraining impact on the low-energy fluid cluster gradually diminishes. This leads to a corresponding reduction in its effect on the total pressure loss. With an increase in the slot height, the restraining impact on corner separation and total pressure loss first rises and then falls. As the through-slot height increases, the suppressive effect on corner separation and loss initially intensifies and then weakens. As the through-slot width increases, the suppressive effect on corner separation and total pressure loss increases steadily. Compared to the original compressor cascade, the through-slot configuration attains peak performance at 25% chord length, with a height of 6% height and a width of 10 mm, reducing the total pressure loss coefficient by 19.22%. Furthermore, as the incoming flow incidence angle enlarges, the enhancement impact of the through-slot configuration on cascade performance initially intensifies and then diminishes. The peak enhancement impact occurs at a 0° incidence angle. At this angle, the configuration can reduce flow loss by 16.72% compared to the original, significantly improving the aerodynamic performance of the high-load compressor cascade. Full article

A hybrid aquatic–aerial vehicle (HAAV) is a novel type of aircraft capable of both aerial flight and underwater navigation. Inspired by the swan’s gliding and landing motion on water surfaces, this study investigates the dynamic modeling and integrated optimization design of an HAAV equipped with a biomimetic skipping plate. By comprehensively accounting for the aerodynamic, impact, hydrodynamic, and frictional forces during the water entry process, a dynamic model for the HAAV’s gliding water entry is established. The reliability of the model is verified through comparisons between numerical simulations and theoretical predictions. Parametric modeling of the skipping plate’s configuration and layout is performed to analyze the influence of different parameters on the water entry dynamics. With the objectives of minimizing the overload and pitch angle variation, a hybrid infilling strategy based on a radial basis function neural network (RBFNN) surrogate model is constructed to improve optimization efficiency. This is combined with a quantum-behaved particle swarm optimization (QPSO) algorithm to conduct the multi-objective optimization of the biomimetic plate, thereby obtaining its optimal configuration and layout parameters. The results demonstrate that the established dynamic model is effective and can accurately capture the kinematic characteristics of the gliding water entry process. The error between the peak load and the pitch angle variation is less than 5%. Compared with the direct QPSO algorithm, the proposed method reduces the number of model evaluations by 66.7%, the computational time by 52.1%, and the optimal solution response value by 12.01%, demonstrating strong potential for engineering applications. Full article

This work presents an integrated experimental and numerical determination of the aerodynamic (lift) characteristics of an ogive forebody equipped with all moving canards. Experimental testing was conducted in the subsonic custom-made wind tunnel of the Vlatacom Institute at a nominal free stream velocity of 32 m/s (and Mach number M = 0.09). Aerodynamic loads on the canards were measured using a custom one-component force balance, while free stream flow properties were obtained via a calibrated Pitot–Prandtl probe on the full-scale geometry model. On the numerical side, RANS simulations were performed in ANSYS Fluent using the k-ω SST turbulence model. Two geometric representations were considered: (a) a high-fidelity configuration explicitly resolving the physical gap between the canard and ogive, and (b) a simplified configuration with the gap removed. Boundary conditions, Reynolds number, and operating parameters were matched to the wind tunnel conditions to enable a strict one-to-one comparison. Particular emphasis was placed on examining the effect of geometric simplification on the predicted lift characteristics. The gap-resolved configuration reproduces the experimentally measured lift curve within approximately 10% across the investigated angle-of-attack range, satisfying conventional aerodynamic validation criteria. The results confirm both the robustness of the applied RANS approach for highly three-dimensional separated flows often found in engineering applications, as well as the reliability of the experimental measurement system. Full article

The purpose of this paper is to present the development of an engineering level code for calculating hypersonic aerodynamics and convective heating, HI-Mach. Novel to this paper are the use of analytic methods for streamline tracing and the direct differentiation of geometric sensitivities for both forces and heat load. Independent panel inclination methods calculate the pressure distribution on the surface of a hypersonic vehicle. Normal shock relations provide the thermodynamic state on each panel. Streamlines are integrated using closed-form streamline equations. Flat plate formulas corrected for compressibility calculate the skin friction coefficient and acreage heat flux on each panel. Formulas for heating on stagnation points and lines, including effects of ellipticity and sweep, are used to calculate stagnation region heating. A method for obtaining the sensitivities of a quantity of interest with respect to the geometry in a hypersonic panel code is described. These are obtained using direct analytical derivatives. The approach is precise and has been thoroughly tested against finite differencing. HI-Mach provides results orders of magnitude faster than would be obtained by CFD. Results from HI-Mach are analyzed and compared to experimental results for the HL-20 lifting body geometry. For the aerodynamic characteristics, HI-Mach predicted force coefficients within 12% of experimental results at $M\infty =4.5$ and 21% at $M_{\infty }=1.6$. Heating results for the HL-20 match experimental and CFD results to within 20% over a wide range of operating conditions. Full article

The development of sustainable and efficient aircraft concepts, such as those featuring flared folding wing tips (FWTs), introduces both aerodynamic and structural challenges. FWTs have demonstrated strong potential for enhancing aerodynamic performance and alleviating gust-induced loads, making them an attractive option for next-generation transport aircraft. This study investigates the load reduction potential of transonic transport aircraft configurations equipped with hinged FWTs, with particular focus on gust impact. Reynolds Averaged Navier Stokes simulations are combined with Gaussian Process regression to evaluate the influence of the fold angle, flare angle, and angle of attack on key quantities of interest, including lift and wing root bending moment coefficients. The GP surrogate model, developed within the Gust Load Alleviation by Non-linear Folding Wing Tip (GUSTAFO) project, accurately reproduces the high-fidelity data while capturing the underlying system uncertainties. The results show that increasing the flare angle within a given folding deflection can reduce the wing root bending moment by up to 38% for flare angles between 0–${45}^{\circ }$ and fold angles between 0–${15}^{\circ }$. These findings highlight the effectiveness of surrogate-based modeling for early-stage design and emphasize the importance of incorporating FWT behavior to achieve accurate, efficient, and robust load predictions. Full article

The paper focuses on the practical benefits of using artificial neural networks (ANNs) in the control of unmanned aircraft vehicles (UAVs) and for the purposes of identification and surveillance. The presented methodology for modeling flight dynamics uses ANNs. Modeling of the object dynamics was based on experimental results obtained during flight tests. The aerodynamic g-loads were derived as a function of the flow parameters. The aim of ANN is to select weights of the neural network in such a way that it simultaneously generates all the necessary parameters to implement into the model with a high fidelity. Full article

Although air resistance represents a relatively small portion of a ship’s total resistance, it can vary significantly for containerships due to loading conditions and container configurations. As containerships grow, their exposed projected windage area increases, leading to higher wind loads that affect maneuverability, heading control, and operational efficiency. Accurately assessing these aerodynamic effects is therefore crucial for both ship design and operational planning. This study investigates the aerodynamic contribution to ship resistance by evaluating the impact of random container configurations on wind loads for a post-Panamax 6750 TEU containership. Numerical simulations are performed at full scale under open-sea conditions using the Reynolds-averaged Navier-Stokes equations with the Realizable k-ε Two-Layer turbulence model. The resulting aerodynamic forces and moments are expressed as non-dimensional wind load coefficients, following ITTC recommendations. Numerical results are compared with methods provided by Blendermann and Isherwood, which are based on systematic wind tunnel measurements. Full article

To address the strong nonlinearity of aerodynamic loads during projectile exterior ballistic flight and the difficulty in accurately modeling fuze dynamic responses, this paper proposes a data-driven modeling and simulation method for fuze exterior ballistic dynamics. A high-fidelity aerodynamic database covering a range of Mach numbers and angles of attack is constructed based on CFD (Computational Fluid Dynamics) simulations. An MLP (Multilayer Perceptron) neural network is then employed to develop an aerodynamic surrogate model, enabling continuous representation of aerodynamic loads within the given sample space. The results show that, within the data coverage range, the proposed model is able to capture the nonlinear variation in aerodynamic parameters and shows improved prediction accuracy compared with the polynomial fitting method. Specifically, for typical aerodynamic parameters, the RMSE (Root Mean Square Error) is reduced from 5.758 to 0.223, the MAE (Mean Absolute Error) is reduced to 0.099, and the R² (Coefficient of Determination) approaches 1. On this basis, the aerodynamic surrogate model is embedded into a six-degree-of-freedom projectile–fuze exterior ballistic dynamics model via the secondary development interface of ADAMS 2020 (Automated Dynamic Analysis of Mechanical Systems), enabling coupled simulation between aerodynamic loads and multibody dynamics. Comparison with firing table data indicates that, under typical operating conditions, the relative deviation of ballistic parameters is generally better than 94%, demonstrating that the proposed method can reasonably reproduce the projectile exterior ballistic characteristics. Furthermore, based on the coupled dynamics model, the dynamic response characteristics of the fuze moving body during the exterior ballistic phase are analyzed. The results indicate that the axial forward overload of the moving body increases significantly with the initial nutation angle, and the variation in the axial projection of gravity induced by nutation plays an important role in its transient response. The proposed approach provides a useful reference for the dynamic response analysis and safety evaluation of fuzes. Full article

Vertical axis wind turbines (VAWTs) suffer from dynamic stall (DS) at low tip-speed ratios (λ), where cyclic variations in angle of attack (α) dominate the blade aerodynamics, severely undermining aerodynamic performance and power extraction. The coupled influence of airfoil parameters on DS remains unexplored. To address this gap, a fully coupled parametric study using 126 incompressible URANS simulations is conducted, examining three geometric parameters of symmetric airfoils: maximum thickness (t/c), chordwise position of maximum thickness (x_t/c), and leading-edge (LE) radius index (I). The results show that coupled geometric modification fundamentally alters the stall mechanism, shifting it from abrupt, LE-driven separation toward a gradual, trailing-edge (TE)-controlled process as airfoils transition from thin, forward-x_t/c profiles to thicker configurations with aft x_t/c and reduced I. This transition enhances boundary-layer (BL) stability, delays DS onset, weakens dynamic stall vortex (DSV) formation, and mitigates unsteady aerodynamic loading. Within the investigated design space, the best-performing configuration (NACA0024–4.5/3.5) achieves a 73% increase in turbine power coefficient (C_P) relative to the baseline airfoil (NACA0018–6.0/3.0), mainly through passive control of BL separation and vortex development. These findings highlight the limitations of single-parameter optimization and establish a physics-based, coupled-design framework for mitigating DS-induced performance losses in VAWTs. Full article

Dragonflies exhibit remarkable flight stability in unsteady environments, largely due to aerodynamic interaction between their forewings and hindwings. This study investigates gust response in dragonfly-inspired micro-aerial vehicles (MAVs) from a system dynamics perspective, with emphasis on the aerodynamic role of tandem-wing interaction rather than control compensation. A six-degree-of-freedom (6DOF) rigid-body framework is developed and coupled with a quasi-steady aerodynamic model that includes explicit phase-dependent interaction between forewing and hindwing forces. Gusts are introduced as time-varying inflow perturbations, allowing physically consistent analysis of how disturbances propagate through aerodynamic loading into vehicle motion. Simulations are performed for representative flight conditions, including gliding, hovering, and gust-perturbed ascent. The results show bounded trajectory, velocity, and attitude responses under sustained gust excitation, even with conservative baseline control. Force and energy analyses indicate that wing–wake interaction redistributes aerodynamic loads in time and reduces peak force and moment fluctuations before they reach the rigid-body dynamics. This behavior is interpreted as passive aerodynamic filtering of gust disturbances inherent to the tandem-wing configuration. Comparative simulations using backstepping control and Active Disturbance Rejection Control (ADRC) further show that the dominant gust attenuation arises from aerodynamic configuration rather than from control action. Although the aerodynamic model is quasi-steady, the framework reproduces key trends reported in biological and CFD-based studies and provides a numerical foundation for future wind-tunnel and free-flight experiments on configuration-level gust attenuation. Full article