Aerodynamic Drag Force Research Articles

Mechanism of active flow control using a novel spike aerodome-channel concept in the hypersonic flow: A numerical study

Among the design requirements of hypersonic vehicles, reducing aerodynamic heating and drag force simultaneously is the main challenge. This paper proposes a novel spike aerodome-channel combination concept to realize the flow field reconstruction around the hypersonic blunt body. The novel configuration is investigated in the axisymmetric flow at a Mach number of 6 at zero angle of attack. The two-dimensional Reynold-averaged Navier–Stokes equations are numerically solved, and the shear-stress transport k–ω model is the turbulence model implemented in this study. Parameters such as spike length and lateral jet location are investigated to explore the drag and heat reduction performance and the flow control features. The obtained results show that the application of the novel spike aerodome-channel concept alters the flow field by eliminating or replacing the strong bow shock wave, and the design of hypersonic vehicles can benefit from the application of the proposed concept. The blunt body coupled with a frustum of cone-tipped spike-channel configuration provides a remarkable drag reduction effect of 20.71% with respect to the case without channel. Considering the effect of lateral jet location, the drag reduction performance of the case with LR = 0.75 is superior to that of the root jet case at the same spike length, and a considerable drag reduction of 28.93% is obtained with L/D = 2.4. In addition, longer spike length is beneficial for improving drag reduction performance, while excellent efficiency of heat protection is obtained in a certain spike length range. For the case of L/D = 1.6 with root jet, the peak Stanton number is significantly decreased by 33.51%.

Comprehensive Analysis of Satellite Deployment Dynamics using MATLAB

A crucial section of area missions is satellite placement, which requires proper management and analysis to guarantee undertaking fulfilment. This paper presents a comprehensive framework for evaluation and simulation of satellite deployment dynamics based on MATLAB. The proposed framework combines visualization processes, dynamics of satellite deployment, and numerical methods to accurately model satellite behaviour all through deployment ranges. The simulation platform uses MATLAB's capability which includes thrust, aerodynamic drag, and gravitational forces to represent the complicated dynamics of satellite deployment. Furthermore, the platform permits multi-satellite deployment situations and parameter-customizable analysis of unmarried and multi-satellite deployments. The performance and acceptability of the MATLAB-primarily based platform is illustrated through case research and overall performance reviews, providing insightful data for planning satellite missions, design optimization, and manipulate strategies. For engineers and academics running on satellite improvement area assignment layout, the proposed framework is a useful resource to better apprehend and examine deployment dynamics underneath numerous operational eventualities.

Wax "Tails" Enable Planthopper Nymphs to Self-Right Midair and Land on Their Feet.

The striking appearance of wax 'tails'-posterior wax projections on planthopper nymphs-has captivated entomologists and naturalists alike. Despite their intriguing presence, the functional roles of these formations remain largely unexplored. This study leverages high-speed imaging to uncover the biomechanical implications of wax structures in the aerial dynamics of planthopper nymphs (Ricania sp.). We quantitatively demonstrate that removing wax tails significantly increases body rotations during jumps. Specifically, nymphs without wax undergo continuous rotations, averaging 4.2 ± 1.8 per jump, in contrast to wax-intact nymphs, who do not complete a full rotation, averaging only 0.7 ± 0.2 per jump. This along with significant reductions in angular and translational velocity from takeoff to landing suggest that aerodynamic drag forces on wax structures effectively counteract rotation. These stark differences in body rotation correlate with landing success: Nymphs with wax intact achieve a near perfect landing rate of 98.5%, while those without wax manage only a 35.5% success rate. Jump trajectory analysis reveals that wax-intact jumps transition from parabolic to asymmetric shapes at higher takeoff velocities and show a significantly greater reduction in velocity from takeoff to landing compared to wax-removed jumps, demonstrating how wax structures help nymphs achieve more stable and controlled descents. Our findings confirm the aerodynamic self-righting functionality of wax tails in stabilizing planthopper nymph landings, advancing our understanding of the complex relationship between wax morphology and aerial maneuverability, with broader implications for wingless insect aerial adaptations and bioinspired robotics.

Experimental investigation of interactions between a water droplet and an airflow boundary layer

The deformation and movement of droplets is widely relevant in many fields of research. The present work experimentally investigates the evolution of a single droplet interacting with an air boundary layer. A series of experiments are carried out using a high-speed photography technique to determine the effects of the airflow velocity, drop height, and droplet size. The morphological characteristics can be classified into three types according to the experiments. The outcomes indicate that both the drop height and the airflow velocity significantly influence the maximum streamwise spreading length, but only the drop height has an impact on the maximum lateral spreading width. The maximum streamwise spreading factor follows a power function relationship with WeRe−0.5. In addition, the crater maximum streamwise and lateral spreading diameters are mainly influenced by the drop height. An energy conversion model is established by considering the effects of the aerodynamic drag force, surface tension, and viscous force. This study provides experimental reference data for the scenario of a droplet interacting with an air boundary layer.

Investigation of Different Windshield Designs for Aerodynamic Drag Force in Motorcycle

This research investigates the aerodynamic performance of different windshielddesigns for the Honda CB500X motorcycleat 140 km/h, focusing on drag force, drag coefficient, and pressure distribution. Three aftermarket windshields and oneoriginal equipment manufacturer(OEM)windshieldwere developed in SolidWorks and simulated using computational fluid dynamics (CFD) in ANSYS Fluent. The OEM windshieldoutperformed the aftermarket designs in terms of aerodynamic efficiency, with a lower drag force (735.65991 N) and drag coefficient (0.3951). However, apressure distribution study found that aftermarket windshields provided better deflection of airflow, resulting in less direct wind effect on the rider, potentially improving rider comfort and safety.These findings highlight the trade-off between aerodynamic efficiency and rider comfort in windshield design.

Identification of Engine Thrust and Aerodynamic Drag Force According to Flight Test Data with Smoothing of Random Measurement Errors

Identification of Engine Thrust and Aerodynamic Drag Force According to Flight Test Data with Smoothing of Random Measurement Errors

The Effect of Arm Movements on the Dynamics of the Wheelchair Frame during Manual Wheelchair Actuation and Propulsion

Wheelchair propulsion and actuation are influenced by the moving masses of the wheelchair user; however, the extent of this effect is still unclear. The main evidence of this effect is that the speed of the wheelchair frame continues to increase after the end of the push phase. The wheelchair’s speed was measured using IMUs and the duration of the push period was recorded using miniaturised pressure sensors attached to the driver’s middle fingers. The velocity and acceleration were determined for various average stroke cycle speeds to determine the speed dependency of the acceleration. The wheelchair was then mounted on a force plate to measure the inertial forces of the hands moving back and forth. The aerodynamic drag and rolling resistance forces were determined from coast-down experiments. Based on the measured forces, the behaviour of the force and velocity profiles was finally modelled by gradually reducing the mass of the arms and thus their inertial force. The results showed that the wheelchair is accelerated throughout the push phase (except for a temporary deceleration in the middle of the push phase at higher velocities), and that this acceleration continues well after the push phase. In the second half of the recovery phase, the wheelchair decelerates. The horizontal inertial forces measured on the force plate are predominantly negative in the push phase and in the second half of the recovery phase, and positive in the first half of the push phase, and their impulse is zero due to the conservation of momentum. Modelling the wheelchair with moving masses showed that reducing the horizontal inertial forces has no effect on the driver’s propulsive force but reduces the velocity fluctuations. The main conclusion of this research is that the wheelchair user’s power should be calculated only from the pure propulsive force that is required in the push phase to overcome the dissipative forces and that enables the gain or loss in speed per stroke cycle, but not directly from the measured velocity.

Thin-airfoil aerodynamics in a rarefied gas wind tunnel: A theoretical study

We study the steady aerodynamic field and loadings about a thin flat plate placed in a wind tunnel under non-continuum conditions. Considering a two-dimensional straight tunnel configuration, the flow is driven by either density or temperature differences between the inlet and outlet tunnel reservoirs, producing a pressure gradient across the channel. Focusing on highly rarefied conditions, we derive a semi-analytic description for the gas flow field in the free-molecular limit for diffuse- and specular-wall configurations. The solution is valid at arbitrary differences between the inlet and outlet reservoirs as well as plate angles of attack α. The results are compared with direct simulation Monte Carlo calculations, indicating that the free-molecular description is valid through O(1) plate-size-based Knudsen numbers. The aerodynamic lift and drag forces are evaluated and their variations with α, reservoir conditions, and tunnel size are analyzed. At a fixed pressure ratio between the outlet and inlet reservoirs, the density-driven flow generates higher aerodynamic loads compared with its counterpart temperature-driven configuration, in line with the associated larger mass flow rate in the former. The results are discussed in light of the existing rarefied-gas description of the free-stream (non-confined) problem.

The Role of Coherent Airflow Structures on the Incipient Aeolian Entrainment of Coarse Particles

AbstractThe role of coherent airflow structures capable of setting gravel‐sized particles in motion is studied theoretically and experimentally. Specifically, a micromechanical model based on energy conservation is proposed to describe the incipient motion of large‐particles ranging from rocking (incomplete entrainment) to incipient rolling (full entrainment). Wind tunnel experiments were conducted on an aerodynamically rough bed surface under near‐threshold airflow conditions. Synchronous signals of airflow velocities upwind of the test particles and particle displacement are measured using a hot film anemometer and a laser distance sensor, respectively, from which coherent airflow structures (extracted via quadrant analysis) and particle movements are interlinked. It is suggested that the incipient motion of gravel‐sized particles (rocking and rolling) may result from sufficiently energetic sweep events corresponding to aerodynamic drag forces in excess of the local micro‐topography resistance. However, full entrainment in rolling mode should satisfy the presented work‐based criterion. Furthermore, using an appropriate probabilistic frame, the proposed criterion may be suitable for describing processes of energy transfer from the wind to the granular soil surface, ranging from the creep transport of gravels to the “mechanical sieving” of mega‐ripples, as well as the transport of light anthropogenic debris (such as plastics).

Compressible FSI of elastic spikes for drag reduction under hypersonic flow

In this study, a new fluid structure interaction (FSI) algorithm is developed for the aerodynamic-elasticity problem, aiming to address the coupling problem between compressible fluids and deformable solid structures. To verify the feasibility of the proposed model, a two-dimensional cantilever panel case under shock waves was conducted. Our numerical results present good consistency with the data from literatures. Furthermore, the validated FSI algorithm is applied on an elastic spike under compressible hypersonic flow. The complicated interaction between the fluid and solid structure under various spike geometry sizes and materials were revealed in respect of the spike deformation, pressure, temperature, and flow fields distribution. The main findings show that the spike deformation largely affects pressure and temperature on the blunt, the aerodynamic drag and lift force, indicating the necessity of FSI. For the spike diameters and lengths, it is found that larger spike diameters and shorter spikes benefits for deformation reduction, thereby minimizing fluctuations in aerodynamic drag force. For spike materials, spikes with larger elastic moduli and lower densities are preferred for the drag reduction. Thus, the proposed FSI model can accurately predict flow fields around and deformations for elastic spikes and offer guidance for drag reduction design in aerospace engineering.

Aerodynamic design optimization of locally built FSR Isuzu bus through numerical simulation

Reducing the fuel consumption of commercial vehicles—especially those used for public transportation—has become increasingly important due to advancements in the automotive industry. On the other hand, the main disadvantages of buses and other commercial vehicles are their fuel consumption, exhaust pollutants, and crosswind stability. Most buses built in Ethiopia have aerodynamic rectangular shapes and strong drag resistance forces, which lead to higher fuel consumption. One of the most accessible buses in Ethiopia is the FSR Isuzu Bus; its external body is locally constructed and has a poor aerodynamic shape. The primary goal of this study is to reduce aerodynamic drag force by improving the outer body shape of the current FSR Isuzu Bus. It also aims to examine the impact of roughness (strip) on the overall aerodynamic characteristics of the bus when it encounters crosswinds, thereby reducing fuel consumption, roll moment, and side force. For computational fluid dynamics (CFD) analysis, ANSYS Fluent is used, and Solidwork is used to model the bus body. A comparison is made between the current CFD analysis of the bus body and the modified design at varying speeds. Three separate models are used in the analysis. At an average speed of 100 kmph, 29.58% (4 to 5 liters) of fuel can be saved, and the drag force is reduced by roughly 49.7% when comparing the new concept to the current bus. By utilizing a strip on the bus’s roof, the side force coefficient and the roll moment coefficient are subsequently reduced from model two to model three by 8.76% and 9.01%, respectively. The study’s conclusions indicate that the external body shape changes have reduced drag; and, adding roof strips has decreased drag to acceptable level and enhanced crosswind stability.

Kriging-based multi-objective optimization on high-speed train aerodynamics using sequential infill criterion with gradient information

For models with large numerical simulation costs, such as high-speed trains, using as few samples as possible to construct a high-precision surrogate model during aerodynamic multi-objective optimization is critical to improving optimization efficiency. This study proposes a sequential infill criterion (SIC) appropriate for the Kriging surrogate model to address this issue. Three multi-objective functions are employed to test the feasibility of constructing a surrogate model based on SIC, and the SIC surrogate model then performs multi-objective aerodynamic optimizations on the high-speed train. The findings indicate that the expected improvement infill criterion (EIC) in the first stage can enhance the global prediction accuracy of the SIC. An infill criterion based on EIC that fuses gradient information (PGEIC) in the second stage is proposed to seek samples in the Pareto front. The PGEIC surrogate model achieves the lowest generational distance and prediction error. The performance of EIC for global search, EIC for Pareto front search, and infill criterion for Pareto front search using only gradient information is poor. The final PGEIC–SIC surrogate model of train aerodynamics has less than 1% prediction error for the three optimization objectives. The optimal solution reduces the aerodynamic drag force of the head car and the aerodynamic drag and lift force of the tail car by 4.15%, 3.21%, and 3.56%, respectively, compared with the original model. Furthermore, sensitivity analysis of key parameters revealed that the nose height v1, cab window height v3, and lower contour line have a greater impact on aerodynamic forces. Moreover, the nose and cab window heights of the optimal model have been reduced, and the lower contour line is concave. Correspondingly, the streamlined shape appears more rounded and slender.

Идентификация транзиентных эффектов в атмосфере Земли при помощи малых космических аппаратов

The paper considers the dynamic aspects of the possibility of carrying out a space mission to study gamma-ray flares of terrestrial origin. We propose an approach to the selection of reference orbits that allows the satellites to form equilateral triangle in the near-equatorial zone. In addition, an algorithm for phasing the satellites by latitude argument using aerodynamic drag forces is proposed.

Phy-Taylor: Partially Physics-Knowledge-Enhanced Deep Neural Networks via NN Editing.

Purely data-driven deep neural networks (DNNs) applied to physical engineering systems can infer relations that violate physics laws, thus leading to unexpected consequences. To address this challenge, we propose a physics-knowledge-enhanced DNN framework called Phy-Taylor, accelerating learning-compliant representations with physics knowledge. The Phy-Taylor framework makes two key contributions; it introduces a new architectural physics-compatible neural network (PhN) and features a novel compliance mechanism, which we call physics-guided neural network (NN) editing. The PhN aims to directly capture nonlinear physical quantities, such as kinetic energy, electrical power, and aerodynamic drag force. To do so, the PhN augments NN layers with two key components: 1) monomials of the Taylor series for capturing physical quantities and 2) a suppressor for mitigating the influence of noise. The NN editing mechanism further modifies network links and activation functions consistently with physics knowledge. As an extension, we also propose a self-correcting Phy-Taylor framework for safety-critical control of autonomous systems, which introduces two additional capabilities: 1) safety relationship learning and 2) automatic output correction when safety violations occur. Through experiments, we show that Phy-Taylor features considerably fewer parameters and a remarkably accelerated training process while offering enhanced model robustness and accuracy.

Evaluation the Aerodynamic Drag Force of CC201 and CC203 Locomotives by CFD Simulation

Trains are a very important mode of transportation for freight and passengers in Indonesia. This encourages PT KAI, which is a train operator in Indonesia, to improve its performance. Currently PT KAI uses several types of locomotives. CC201 locomotives made in 1977-1978 and CC203 made in 1995 are locomotives that are still widely operated. Fuel consumption is one of the components of train operating costs, the percentage of which reaches more than 30%. Railroad fuel consumption is strongly influenced by various factors, one of which is the aerodynamic performance of the locomotive. This study presents an evaluation of the aerodynamic performance of CC201 and CC203 locomotives. The research stages include direct measurement of locomotive geometry and dimensions, CAD drawing creation using SoildWorks and aerodynamic evaluation using ANSYS software. The simulation results show that the flat front design of the CC201 locomotive has greater aerodynamic resistance. This can be seen from the pressure contours and turbulence around the locomotive body. This causes the drag force of the CC201 locomotive to be 44% greater than that of the CC203 locomotive.

Analisis Ketahanan Rangka Stasiun Pengisian Kendaraan Listrik Berbasis Panel Surya Portabel Terhadap Laju Angin

High wind velocity can induce external pressures and loads on the structural framework of an Electric Vehicle Charging Station (EVCS), jeopardizing the overall stability and structural integrity of the framework. The objective of this research is to ascertain the magnitude of aerodynamic drag force and the maximum pressure values on the surface of the EVCS framework, with respect to variations in wind velocity. The methodology employed in this study involves Computational Fluid Dynamics (CFD) simulations utilizing the Solidworks Flow Simulation. Three wind velocity scenarios were considered: 3 km/h, 6 km/h, and 9 km/h, allowing for the observation of airflow acceleration phenomena, aerodynamic drag force values, and peak pressure distributions on the EVCS framework's surface. Research findings reveal that the aerodynamic drag force at a wind velocity of 3 km/h measures 22,34 N, escalating to 90,42 N at 6 km/h wind velocity, and reaching 202,7 N at 9 km/h wind velocity. Furthermore, the highest-pressure value at a wind velocity of 3 km/h is 101325,45 Pa. As the wind velocity increases to 6 km/h, the maximum pressure value rises to 101338,18 Pa. Under the condition of the highest input wind velocity, i.e., 9 km/h, the peak pressure reaches 101353,46 Pa.

Effect of upstream flow characteristics on the wake topology of a square-back truck

The influence of upstream flow characteristics on the bi-stable flow structure in the wake region of a simplified square-back heavy vehicle model at a Reynolds number of 2.7 × 104 was investigated by using the improved delayed detached eddy simulation method. The asymmetric wake structure of this model and its corresponding aerodynamic response were examined, aiming to identify the effect mechanism of three inlet profiles on the asymmetric wake structure of the named ground transportation system (GTS) model in simulations. The accuracy of the numerical method used in this study was validated by comparison with wake structure data, including the flow states, vortex core's location, and aerodynamic drag obtained from previous large eddy simulations and water channel experiments. The numerical results show that different turbulent inlet velocity profiles lead to different wake topologies. When the turbulent velocity profile with a turbulence intensity of 15% generated by TurbSim, a stochastic inflow turbulence tool for generating turbulent velocity inlet on an atmospheric boundary layer profile, is used, the expected bi-stable flow topology is still observed, but it is not shown in the case by means of the turbulence generator incorporated into ANSYS Fluent. Those turbulent inlet velocity profiles contribute to the increase in GTS model's aerodynamic drag forces. Compared to the uniform velocity profile, the TurbSim velocity profile can achieve a drag increase in 7.23%. In addition, this turbulent profile intensifies the flow fluctuations in the wake region and enhances the transient response frequency of the wake region. Thus, when assessing the vehicle aerodynamic performance in open air, especially under crosswinds, the real turbulence velocity profile, e.g., the profile generated by TurbSim in the current study, is recommended to be used for a more accurate prediction in numerical simulations.

High-Fidelity Drone Simulation with Depth Camera Noise and Improved Air Drag Force Models

Drone simulations offer a safe environment for collecting data and testing algorithms. However, the depth camera sensor in the simulation provides exact depth values without error, which can result in variations in algorithm behavior, especially in the case of SLAM, when transitioning to real-world environments. The aerodynamic model in the simulation also differs from reality, leading to larger errors in drag force calculations at high speeds. This disparity between simulation and real-world conditions poses challenges when attempting to transfer high-speed drone algorithms developed in the simulated environment to actual operational settings. In this paper, we propose a more realistic simulation by implementing a novel depth camera noise model and an improved aerodynamic drag force model. Through experimental validation, we demonstrate the suitability of our models for simulating real-depth cameras and air drag forces. Our depth camera noise model can replicate the values of a real depth camera sensor with a coefficient of determination (R2) value of 0.62, and our air drag force model improves accuracy by 51% compared to the Airsim simulation air drag force model in outdoor flying experiments at 10 m/s.

NEW PRODUCT DESIGN AS PART OF THE DIGITAL FACTORY CONCEPT

The concept of digital production represents the basis for the development of a digital production system, i.e. a digital factory. The digital factory represents the integration of the virtual and real factory. Inside the virtual factory, products, processes and resources are modeled on the basis of real data, which are then tested, improved and optimized through the application of digital production tools. Finally, when the results of the virtual factory are verified and all possible irregularities are removed, they can be applied in the real factory.
 The primary goal of this paper is to present the process of designing a new product. The design process is an integral part of the modern digital factory concept. The concept requires full integration of product data, as well as systems for design, planning and production, including the design of technological processes.
 The aim of this paper is to solve the problem of the budget coefficient of aerodynamic drag force of axisymmetric aircraft without wings. The problem is interesting because it provides a simple calculation of the axial aerodynamic coefficient of drag force for different airspeed. Ruling allows for easier comparison of the components of aerodynamic force coefficient of drag when changing airspeed and experimental values ​​from wind tunnel. The dependences of aerodynamic coefficients of aerodynamic parameters and shape aerodynamic configuration.The application of the proposed solutions will accelerate the flow of information theoretical researches aerodynamics of the aircraft. The accuracy in determining the values ​​of aerodynamic coefficients is one of the key factors for the assessment of flight "rapidly rotating" axisymmetric bodyes.

How Magnetic Erosion Affects the Drag-Based Kinematics of Fast Coronal Mass Ejections

In order to advance our understanding of the dynamic interactions between coronal mass ejections (CMEs) and the magnetized solar wind, we investigate the impact of magnetic erosion on the well-known aerodynamic drag force acting on CMEs traveling faster than the ambient solar wind. In particular, we start by generating empirical relationships for the basic physical parameters of CMEs that conserve their mass and magnetic flux. Furthermore, we examine the impact of the virtual mass on the equation of motion by studying a variable-mass system. We next implement magnetic reconnection into CME propagation, which erodes part of the CME magnetic flux and outer-shell mass, on the drag acting on CMEs, and we determine its impact on their time and speed of arrival at 1 AU. Depending on the strength of the magnetic erosion, the leading edge of the magnetic structure can reach near-Earth space up to ≈ three hours later, compared to the non-eroded case. Therefore, magnetic erosion may have a significant impact on the propagation of fast CMEs and on predictions of their arrivals at 1 AU. Finally, the modeling indicates that eroded CMEs may experience a significant mass decrease. Since such a decrease is not observed in the corona, the initiation distance of erosion may lie beyond the field-of-view of coronagraphs (i.e. 30~mathrm{R}_{odot }).