The Effect Of The Rotating Wheels On The Numerical Simulation Of Flow Field Around Automobile

The aerodynamic quality is one of the most important characteristics for automobile. It has a direct effect on automobile's power performance, the fuel efficiency and the control stability. The numerical simulation is an important method for studying the automobile's aerodynamics quality nowadays. In the numerical simulation of its external flow field, the automobile's body is usually simplified and the appendix such as the rearview mirror, the wheel etc. is ignored. As an important component of automobile body, the wheels increase the aerodynamic drag which can be accounted for 30% of the entire vehicle drag force. Hence, we can conclude that the wheels have an important influence on automobile's aerodynamics. In addition, the base flow field of the automobile body further complicates as a result of the wheels function, which also directly affects the entire vehicle's aerodynamic characteristic. Therefore, it's important to understand and to master the nearby flow field characteristic of the wheels and its influence on the entire vehicle's external flow field; it has such an important effect for improving and enhancing the automobile's aerodynamic properties.In this issue, firstly, the chosen turbulence model and the calculation accuracy of grid is gained by numerical simulation on Ahmed blunt body. The purpose in doing so is to ensure the follow-up results' reliability of this computation. And the changes of Ahmed blunt body's aerodynamic characteristics are also obtained by comparing the stilt in use and the stilt not been used. Secondly, the performance of single wheel's aerodynamic characteristic is analyzed both when it's in vacant and on land. Lastly, by choosing a domestic common automobile as the computation model, the differences of model's aerodynamic characteristics are compared on the condition of the auto body without wheels, with fixed wheels and with rotating wheels. And the detailed analysis of the flow field near the wheels is also done, as well as its influence to the entire vehicle's aerodynamic characteristics.The results confirmed that, the stilt has a major impact on Ahmed blunt body's aerodynamic characteristics; In the computation of both drag force and lift force, the error is bigger for the non-wheel model while the result tallies well for the model with wheels; Wheels are important appendix for producing drag and lift force; And also wheels have major impact on the turbulent flow shape of the body's rear part, as well as fixed wheels and rotating wheels do, and the coefficient of aerodynamic force gained by calculating is relatively close; It cannot be right or meet the actual project's requirements if the numerical simulation of automobile's external flow fields is ignored, for wheels affect the entire vehicle's external flow fields directly.