涡流发生器对3/4汽车模型风洞流场品质的影响

采用数值计算的方法对3/4开口回流式汽车风洞喷口处的涡流发生器进行了研究.对比研究了三种不同片数的涡流发生器对流场品质的影响.首先采用定常雷诺时均纳维斯托克斯方程求解了流场的定常特性,接着采用大涡模拟(LES)方法对流场的非定常特性进行了研究.并就两种计算方法给予了相应的试验验证.对比计算结果得到涡流发生器可以在一定程度上提高流场均与性,尤其是三片式涡流发生器的工况能较好地拓宽风洞测试区的高流速区域的范围,降低测试区的静压梯度,减小试验段内的湍流度和剪切层内的湍流度,延长测试段内低湍流区的长度,分散流场内的脉动能量,降低低频颤振敏感频率区的能量聚集.

Effect of Vortex Generator to Flow Field Quality in 3/4 Open Jet Automotive Wind Tunnel

Computational fluid dynamics (CFD) method was applied to studying the vortex generator effects toward 3/4 open jet automotive wind tunnel. Three vortex generators with varied plate numbers were studied separately. Firstly, the steady Reynolds Averaged Navier Stokes(RANS) method was adopted to get the steady characteristics of the flow field. Then the large eddy simulation (LES) method was used to get the unsteady characteristics of the flow field. The corresponding tests were carried out to validate the simulation methods. A comparison of the simulation results show that with the vortex generators especially the generator with three plates, the uniformity inside the flow field increases. The test section range with high speed flow is enlarged. The static pressure gradient in the axial direction is reduced and the turbulence intensity inside test section and prism layer is reduced, too. The length of test section with low turbulence intensity is extended. The turbulence energy inside flow is dispersed. The energy is minimized within the frequency range sensitive to the buffeting phenomenon.