Features of determining the car aerodynamic drag coefficient and its influence on fuel consumption

Abstract

The article discusses the determination of the aerodynamic drag coefficient of a car using CFD modeling and the experimental free run method. The influence of the Cx coefficient on vehicle fuel consumption has been studied. The study was carried out on a Nissan Terrano 3. Computer modeling was performed using the domestic FlowVision CFD module. The features of the formation of the model are considered. Special attention is paid to the selection of solver settings and adaptation of the computational grid using the example of a verification model - the Ahmed body. The calculation results are presented in the form of visualization, in numerical values and graphical form. The values of the forces acting on the elements of the car and the coefficients Cx for flow around at a speed of 57 km/h were obtained. The coefficient Cx was determined experimentally using empirical dependencies. A justification is given for the discrepancy between the results of calculation and experiment related to assumptions in the geometry of the car and boundary conditions during modeling. The influence of the coefficient on the power expended on aerodynamic drag has been established. When the Cx coefficient decreases by 0,05, the consumed power is reduced by 12%. The influence of this coefficient on vehicle fuel consumption was also revealed.