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The purpose of this paper is to investigate the mechanism and performance of a potential strategy, which is to enhance turbulence to carry out drag reduction for heavy trucks.

Enhancing turbulence deflector (ETD) was placed on the roof surface of an ground transportation system (GTS) to investigate the drag reduction mechanism of enhancing turbulence. Transition shear-stress transport improved delay detach eddy simulation model was adopted to simulate the unsteady small-scale flow around the ETD.

By optimizing the three influencing factors, diameter, streamwise length and streamwise position, the optimized ETD has achieved a maximum drag reduction of 7.04%. The analysis of flow field results shows that enhancing turbulence can effectively suppress flow separation and reduce the negative pressure intensity in the wake region of GTS.

The present work provides another potential possibility for the improvement of the aerodynamic performance of heavy trucks.

This study aims to achieve optimum flow separation control for a road vehicle using a reverse flow fan on rear side.

A full-length reverse flow fan array (fan’s air speed is 50% of the car’s speed) is attached throughout the width of the vehicle at rear edge corner.

The reverse flow fan array positioned at rear edge of car pushes the airflow against the car’s rear window. It creates the recirculation region and alters the pressure distribution. This reduces the lift coefficient by 150%, which becomes the downforce and reduces the drag coefficient by 22%. As the car speed increases, fan speed should also be increased for effective flow control.

This active flow control method for 3D Ahmed car body has been studied computationally at low speed (40 m/s).

This design increases the downforce, thus gives better cornering speed and stability, and decreases the drag which improves fuel efficiency. It can be used for effective flow control of cars (hatchback/sedan). The findings can be applied to the bluff bodies, road vehicles, UAV and helicopter fuselage for flow separation control.

The fan array is attached on car’s rear side, which blows air against the car’s rear window. It alters the pressure distribution and aerodynamics forces favorably. But the existing high-speed fan used in a sports cars sucks the air from bottom and pushes it rearward, which increases both the traction force and drag.

The aim of this article is to minimize the drag of an unmanned amphibious aerial vehicle (UAAV) and enhancing the endurance.

Various surface geometrical profiles such as rectangular, semicircular groove, razor blade and V-groove riblets are incorporated into the UAAV, and computational fluid dynamic (CFD) analysis is performed for various angles of attack at diverse vehicle speed conditions to estimate the coefficient of drag considering k–e turbulence model. Comparative evaluation between riblet and blunt body shape methodology is performed. Wind tunnel experiments are conducted to validate the flow characteristics around the UAAV.

It is observed that V-groove riblet method produced minimal drag in comparison with other profiles. The pressure distributions around UAAV for various geometrical profiles suggested that V-groove profile has achieved minimal vortex region, flow separation and turbulent boundary layer near to the outer profile.

The CFD analysis of UAAV for various riblet configurations and validation with wind tunnel smoke test confirms that UAAV with V-groove riblet provides low drag.

The purpose of this paper is to study pressure measurement correlations, as the location of the pressure sensors should enable to capture variation of the drag force depending on the yaw angle and some geometrical modifications.

The present aerodynamical study, performed on a reduced scale mock-up representing a sport utility vehicle, involves both numerical and experimental investigations. Experiments performed in a wind tunnel facility deal with drag and pressure measurements related to the side wind variation. The pressure sensor locations are deduced from wall streamlines computed from large eddy simulation results on the external surfaces of the mock-up.

After validation of the drag coefficient (Cd) values computed with an aerodynamic balance, measurements should only imply pressure tap mounted on the vehicle to perform real driving emission (RDE) tests.

Relation presented in this paper between pressure coefficients measured on a side sensor and the drag coefficient data must enable to better quantify the drag force contribution of a ground vehicle in RDE tests.

The purpose of this paper is to present numerical investigations of the flow dynamic characteristics of a 47° Ahmed Body to identify wake flow control strategy leading to drag coefficient reduction, which could be tested later on sport utility vehicles.

This study begins with a mean flow topology description owing to dynamic and spectral analysis of the aerodynamic tensor. Then, the sparse promoting dynamic modal decomposition method is discussed and compared to other modal approaches. This method is then applied on the wall and wake pressure to determine frequencies of the highest energy pressure modes and their transfers to other frequency modes. This analysis is then used to design appropriated feedback flow control strategies.

This dynamic modal decomposition highlights a reduced number of modes at low frequency which drive the flow dynamics. The authors especially notice that the pressure mode at a Strouhal number of 0.22, based on the width between feet, induces aerodynamic losses close to the rear end. Strategy of the proposed control loop enables to dampen the energy of this mode, but it has been transferred to lower frequency mode outside of the selected region of interest.

This analysis and methodology of feedback control shows potential drag reduction with appropriated modal energy transfer management.

In this paper, an innovative hybrid intelligent position control method for vertical take-off and landing (VTOL) tiltrotor unmanned aerial vehicle (UAV) is proposed. So the more accurate the reference position signals tracking, the proposed control system will be better.

In the proposed method, for the vertical flight mode, first the model reference adaptive controller (MRAC) operates and for the horizontal flight, the model predictive control (MPC) will operate. Since the linear model is used for both of these controllers and naturally has an error compared to the real nonlinear model, a neural network is used to compensate for them. So the main novelties of this paper are a new hybrid control design (MRAC & MPC) and a neural network-based compensator for tiltrotor UAV.

The proper performance of the proposed control method in the simulation results is clear. Also the results showed that the role of compensator is very important and necessary, especially in extreme speed wind conditions and uncertain parameters.

Novel hybrid control method. 10;-New method to use neural network as compensator in an UAV.

This paper aims to provide the results of investigations concerning an influence of the tyre with longitudinal grooves on the car body aerodynamics. It is considered as an important aspect affecting the vehicle aerodynamic drag.

To investigate a contribution of grooved tyres to the overall vehicle drag, three wind tunnel experimental campaigns were performed (two by Peugeot Société Anonyme Peugeot Citroen, one at the Lodz University of Technology). In parallel, computational fluid dynamics (CFD) simulations were conducted with the ANSYS CFX software to enable formulation of wider conclusions.

The research shows that optimised tread patterns can be derived on a single tyre via a CFD study in combination with a controlled experiment to deliver designs actively lowering the overall vehicle aerodynamic drag.

A reduction in the aerodynamic drag is one of ways to decrease vehicle fuel consumption. Alternatively, it can be translated into an increase in the maximum travel velocity and the maximum distance driven (key factor in electric vehicles), as well as in a reduction of CO₂ emissions. Finally, it can improve the vehicle driving and steering stability.

The tyre tread pattern analysis on isolated wheels provides an opportunity to cut costs of R&D and could be a step towards isolating aerodynamic properties of tyres, irrespective of the car body on which they are applied.

The purpose of this paper is to investigate the optimal average drag coefficient of the Ahmed body for mixed platoon driving under crosswind and no crosswind conditions using the response surface optimization method. This study has extraordinary implications for the planning of future intelligent transportation.

First, the single vehicle and vehicle platoon models are validated. Second, the configuration with the lowest average drag coefficient under the two conditions is obtained by response surface optimization. At the same time, the aerodynamic characteristics of the mixed platoon driving under different conditions are also analyzed.

The configuration with the lowest average drag coefficient under no crosswind conditions is 0.3 L for longitudinal spacing and 0.8 W for lateral spacing, with an average drag coefficient of 0.1931. The configuration with the lowest average drag coefficient under crosswind conditions is 10° for yaw angle, 0.25 L for longitudinal spacing, and 0.8 W for lateral spacing, with an average drag coefficient of 0.2251. Compared to the single vehicle, the average drag coefficients for the two conditions are reduced by 25.1% and 41.3%, respectively.

This paper investigates the lowest average drag coefficient for mixed platoon driving under no crosswind and crosswind conditions using a response surface optimization method. The computational fluid dynamics (CFD) results of single vehicle and vehicle platoon are compared and verified with the experimental results to ensure the reliability of this study. The research results provide theoretical reference and guidance for the planning of intelligent transportation.

The purpose of this paper is to study the aerodynamic characteristics of Ahmed body in longitudinal and lateral platoons under crosswind by computational fluid dynamics simulation. It helps to improve the aerodynamic characteristics of vehicles by providing theoretical basis and engineering direction for the development and progress of intelligent transportation.

A two-car platoon model is used to compare with the experiment to prove the accuracy of the simulation method. The simplified Ahmed body model and the Reynolds Averaged N-S equation method are used to study the aerodynamic characteristics of vehicles at different distances under cross-winds.

When the longitudinal distance x/L = 0.25, the drag coefficients of the middle and trailing cars at β = 30° are improved by about 272% and 160% compared with β = 10°. The side force coefficients of the middle and trailing cars are increased by 50% and 62%. When the lateral distance y/W = 0.25, the side force coefficients of left and middle cars at β = 30° are reduced by 38% and 37.5% compared with β = 10°. However, the side force coefficient of the right car are increased by about 84.3%.

Most of the researches focus on the overtaking process, and there are few researches on the neat lateral platoon. The innovation of this paper is that in addition to studying the aerodynamic characteristics of longitudinal driving, the aerodynamic characteristics of neat lateral driving are also studied, and crosswind conditions are added. The authors hope to contribute to the development of intelligent transportation.

The purpose of this study is to explore the effects of aerospike and hemispherical aerodisks on flow characteristics and drag reduction in supersonic flow over a blunt body. Specifically, the study aims to analyze the impact of varying the length of the cylindrical rod in the aerospike (ranging from 0.5 to 2.0 times the diameter of the blunt body) and the diameter of the hemispherical disk (ranging from 0.25 to 0.75 times the blunt body diameter). CFD simulations were conducted at a supersonic Mach number of 2 and a Reynolds number of 2.79 × 10⁶.

ICEM CFD and ANSYS CFX solver were used to generate the three-dimensional flow along with its structures. The flow structure and drag coefficient were computed using Reynolds-averaged Navier–Stokes equation model. The drag reduction mechanism was also explained using the idea of dividing streamline and density contour. The performance of the aero spike length and the effect of aero disk size on the drag are investigated.

The separating shock is located in front of the blunt body, forming an effective conical shape that reduces the pressure drag acting on the blunt body. It was observed that extending the length of the spike beyond a specific critical point did not impact the flow field characteristics and had no further influence on the enhanced performance. The optimal combination of disk and spike length was determined, resulting in a substantial reduction in drag through the introduction of the aerospike and disk.

To predict the accurate results of drag and to reduce the simulation time, a hexa grid with finer mesh structure was adopted in the simulation.

The blunt nose structures are primarily employed in the design of rockets, missiles, and re-entry capsules to withstand higher aerodynamic loads and aerodynamic heating.

For the optimized size of the aero spike, aero disk is also optimized to use the benefits of both.