汽车风洞试验段非定常流场的试验

采用三维热线风速仪测量了不同工况下某全尺寸汽车风洞1∶15模型风洞试验段内的非定常流场.对测点自功率谱密度(PSD)分析表明,对于喷口风速小于37m.s-1的低速工况,湍流能量主要集中在20Hz附近,当喷口风速为25m.s-1时,该频率对应的PSD数值最大;喷口风速大于37m.s-1的高速工况,湍流能量主要集中在43Hz附近,当喷口风速为41m.s-1时,该频率对应的PSD数值最大.无论是高速工况还是低速工况,气流从喷口到收集口处脉动速度的振动幅值都逐渐增加,且在高速工况下的脉动速度幅值增量明显大于低速工况.通过试验还发现脉动速度在收集口角度为0°的工况下的振动能量远高于收集口角度为15°的工况.

Test Research of Unsteady Characteristic of Flow Inside Test Section of Automotive Wind Tunnel

Three dimensional hot-wire was used to test the unsteady characteristic of the flow inside the test section of an 1:15 scaled wind tunnel under the different situations. By analyzing the PSD data of the test points, we got the following conclusions: When nozzle speed was lower than 37m/s the turbulent density was concentrate at the frequency of about 20Hz. At the speed of 25m/s the PSD value was max. When nozzle speed was higher than 37m/s the turbulent density was concentrate at the frequency of about 43Hz. At the speed of 41m/s the PSD value was max. Under both low speed and high speed situations the peak of the velocity fluctuations were all enlarged along with the flow from nozzle to collectors. And the amplification was larger under the situation of high speed. From test we also found that when the angle of the collectors was 0 degree the velocity fluctuations were much lower than that of 15 degree collectors.