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Considering the aerodynamic characteristics of the vehicle traveling under the crosswind and the complexity of the flow field change, this paper uses overset mesh of STAR CCM+ software to carry out CFD simulation analysis on the aerodynamic characteristics of heavy commercial vehicles passing through the highway tunnel of which entrance and exit exist crosswind. Corresponding aerodynamic coefficients and flow field changes around the body at different crosswind speeds and different tunnel forms are monitored. The results show that the yaw moment is sensitive to the speed of crosswind. When a heavy commercial vehicle passes through a tunnel where crosswind increases from 10m/s to 13m/s,the yaw moment change rate increases from 34.8 kN•m/s to 45.9 kN•m/s. It also can be seen in these results is that when passing through two tunnels with a distance, the heavy commercial vehicle’s side force, roll moment and yaw moment change because of the surrounding periodic variation of flow field.

The underbody diffusers are used widely in race cars to improve the flow field structure at the bottom of the car and provide enough downforce. In recent years, passenger cars have begun to use bottom diffuser to improve aerodynamic characteristics, so as to reduce drag and increase downforce. In this paper, the aerodynamic characteristics of the bus with different underbody diffuser angles and channel numbers are studied by numerical simulation analysis. Firstly, the aerodynamics of the bus under different diffuser inlet and outlet angles are studied, and then an optimal inlet and outlet angle is determined based on the simulation results. Then, using this angle as a constant, the 2, 3, and 4 channel numbers were chosen as the diffuser channel variables to study the influence of the multiple-channel diffusers on the aerodynamic drag of the vehicle.

At present, there are two main simulation methods for the engine compartment thermal management system, which are called one-dimensional(1D) and three-dimensional(3D) simulation. 1D simulation can reflect the overall performance parameters of the thermal management system. The 3D simulation provides a flow field distribution inside the engine compartment, that provides precise guidance for local temperature field control. In this paper, the 1D and 3D coupling simulation method was used in the development of automobile thermal management, which shortened the simulation cycle under the premise of ensuring the calculation accuracy. Firstly, the cold flow field simulation of the engine compartment was performed, and the relevant results such as air flow and pressure drop coefficient was imported into the 1D simulation model as an input parameter for correction, and the 1D calculation result was used as an input to calculate the 3D temperature field.

It aims to study the unsteady flow characteristic of the side-view mirror wake field, and reduce the wind noise by means of unsteady flow control. In this paper, the PIV test in a wind tunnel is used to capture the unsteady flow in the wake field of the side-view mirror, which is used to verify the accuracy of the steady simulation method with RANS after being averaged. Then LES turbulence model is used to obtain the wind noise, and the unsteady flow characteristic like vortex shedding of the side-view mirror is studied. The results show that, in the wake of the side-view mirror, there is a vortex pair similar to Karman Vortex Street. In both horizontal and vertical sections, these two vortexes are respectively separated from the upper and lower edges of the side-view mirror. Accompanied by a significantly uncertain periodic shedding, they continue to extend back until dissipating.

Formula One (F1) racing cars are often running at high-speed with the pitching angle changing frequently due to road conditions. These pitching angle changes result in changes to the car’s aerodynamic characteristics that will directly affect handling stability and other performance factors including safety. This paper takes a F1 racing car as the model; the influence of the change of pitching angle on aerodynamic drag force and lift force are investigated. CFD code-PowerFLOW based LBM is used to simulate the aerodynamic characteristics with different pitching angles. The distribution of aerodynamic coefficients, velocity and pressure in the flow field are obtained; and the differences between different pitching angles were analyzed. The results show that as the pitching angle increases, the drag force increases and the lift force decreases. The down-force of the car is mainly supplied by the front wing and the rear wing.

It is known that the automobile cabin thermal comfort, could keep the driver and passengers feel better which has a great effect on traffic safety. In this paper, to the FAW truck cab, we did some researches about automobile cabin thermal comfort. Our plan is to calculate the air flow distribution and the temperature in steady and transient state when there is warm or cool air flow. The heating and cooling experiment methods standard of cabin are based on the national standard and the automobile industry standard of China. Then the numerical simulation process becomes very important. So we used the commercial CFD code- STAR-CCM+ for study in this paper. Firstly, Geometry Clean up. Secondly, Wrap and Remesh, we chose the internal surface at the wrap surface of cabin and air conditioning pipes, then we remesh the surface. Thirdly, generate the volume mesh which is polyhedral mesh, and the number of the volume mesh is 9.4 millions.

Automobile industry is facing the great challenge of energy conservation and emission reduction. It's necessary to do some researches on some surface components of a car body to find out which of them may affect aerodynamic drag remarkably. This will help an aerodynamic engineer modify an initial car model more clearly. We also hope to reduce the cost during the process, including time and resources. In this paper, with the purpose of developing an aerodynamic shape optimization process and realizing its automation, a MIRA reference car model was studied and three commercial softwares were integrated-Altair HyperStudy, HyperMesh and CD-adapco STAR-CCM+. The optimization strategy in this paper was: firstly, a DOE (design of experiment) matrix, which contained four design factors and thirty levels was created. The baseline model was morphed according to the DOE matrix. Then the morphed model's aerodynamic drag coefficient (Cd) and lift coefficient (Cl) were calculated via CFD software.

Similar to the traditional method of aeronautical wind tunnel testing a procedure to correct for support interference and wind tunnel interference in the automotive wind tunnel of Jilin University is described. Due to the fact that a moving belt is installed in the centre region of the test section the model was kept in place by an external support system. However, for our tests the moving belt was stationary. In order to separate the different interference effects two tests were carried out with the car model connected and disconnected from the support-structure linked to a six-component underfloor balance. In this way the aerodynamic force on a car model, which is then still contaminated by wind tunnel interference effects and the secondary interference effects of the model support on to the car model can be determined.