Strategy of Active Flow Control to Reduce Aerodynamic Drag with Steady Jet for 25°Ahmed Model

Abstract:

Based on computational fluid dynamics(CFD) numerical simulation method, aerodynamic drag reduction of 25°Ahmed model with active flow control of steady jet are researched using shear stress transport(SST) κ-ω turbulent model. Jet holes are located at the model tail to study the optimum parameters of hole diameter, distance to the nearest side edge, shape, jet velocity and jet angle, and to analyze the influence of different jet state to the flow structure, total drag coefficient and local drag coefficient. In addition, the numerical simulation results are in good agreement with the date from wind tunnel experiment, which verifies the accuracy and reliability of present numerical method. The numerical results indicate that the wake structure with flow control is significantly improved and the longitudinal vortex is effectively suppressed, compared to the one without control. Simultaneously, the drag coefficient significantly decreases. In the scheme of placing jet hold on the single location, the one placing jet at the top of slant get the lowest drag coefficient 0.252 2 (with 11.3% drag reduction). The drag coefficient of the optimal combining scheme obtained by orthogonal experiment method is 0.246 7 (with 13.23% drag reduction).

Key words:external flow field; active control; wake structure; jet flow; aerodynamic drag reduction