开口式风洞喷口来流风速的修正

Velocity Correction of Nozzle in 3/4 OpenJet Wind Tunnel

摘要:

采用数值仿真方法对1∶15的３／４开口回流式汽车风洞进行模拟，并将喷口法和驻室法推导得到的风速与风洞喷口来流风速监测值进行对比，提出来流风速的修正方案.与风洞试验数据对比，验证了数值仿真方法的有效性.空风洞仿真结果表明：在不同来流风速下，两种方法计算结果皆与风洞喷口来流风速监测值接近.安装车辆模型的风洞计算结果表明：在不同雷诺数下，由于安装车辆导致的阻塞作用，喷口附近的压力受到影响，两种方法推导得到的风速皆需进一步修正.用于压差修正的系数，是依赖于风速的高阶多项式，可有效降低风速测量的误差.

关键词:汽车风洞; 数值仿真; 喷口法; 驻室法; 风速修正

Abstract:

In this paper, numerical simulation is employed to calculate the flow field in 1∶15 wind tunnel with 3/4 openjet test section. Two measurement methods of wind speed tested at the nozzle and the chamber were adopted and a correction method of velocity data derived from wind tunnel test is proposed based on comparative analysis. Simulation results indicate that, for empty wind tunnel at the different upstream velocities, the two methods both show good agreement with test data; for wind tunnel with car model in the test section at the wind speed of different Reynolds numbers, the predicted velocity results of both two methods need to be corrected due to the blockage effect of test model on the pressure distribution around the nozzle area. The coefficient for pressure correction can effectively improve the prediction accuracy of wind speed, because it is a higherorder polynomial term depending on the upstream velocity.

Key words:automotive wind tunnel; numerical simulation; nozzle method; plenum method; wind speed correction