Airflow direction influence on aerodynamic forces acting on a vehicle

Introduction. The paper considers the airflow around a railway car at different directions of its speed. The main purpose of the study is to determine the values of the longitudinal and transverse forces acting on the car for the entire possible range of changes in the angle of attack of the airflow.Materials and methods. The simulation of airflow aerodynamics is performed in the ANSYS CFX software package, designed to perform tasks using the finite volume method. During the calculation, the Reynolds-averaged Navier–Stokes equations were numerically solved, and for their closure was used the k–ε turbulence model.Results. The authors obtained dependences of the distribution of flow velocities and pressures on the frontal and lateral surfaces of the vehicle, as well as the values of the longitudinal and transverse forces acting on the car from the wind for different values of the angle of attack of the airf low. It is shown that the value of the angle of attack of the airflow has a significant effect on the positions of the current lines and the values of aerodynamic resistance coefficient of the car. During the calculations, it was found that the longitudinal force acting on the vehicle under consideration is maximum at the values of the angle of attack of the airflow from 10 to 30°. The greatest transverse forces are realised at angles of attack from 45 to 90°.Discussion and conclusion. The developed method of computer simulation of streamline by airflow may be used to analyse the aerodynamic forces acting on other vehicles. The obtained results during calculations could be used in the digitalisation of production processes for the operation of railway rolling stock.