多孔介质对风洞管道内压缩波传播的影响

Influences of porous media on propagation of compression wave in wind tunnel

磁浮飞行风洞运行中产生的压缩波在风洞管道内传播至风洞端面后反射,可能在测试段与模型发生碰撞,干扰试验结果。为了消除压缩波对风洞试验的影响,采用在风洞管道内部铺设多孔介质的方式降低风洞内压缩波强度,依据现有的多孔介质压降模型推导管道内压缩波通过多孔介质区域压降规律方程,并根据方程内影响多孔介质消波能力的参数进行了数值模拟。结果表明:多孔介质对不同强度压缩波均有相似比例的压降作用,其消波能力随压缩波强度、多孔介质惯性阻力系数及厚度的增大而增大;但当多孔介质惯性阻力系数及厚度增大时,部分压缩波不能通过多孔介质而是被其反射,反射压缩波强度也随惯性阻力系数及厚度的增大而增大。增加层数可以在不改变多孔介质其他参数的情况下降低反射压缩波强度,提高多孔介质的总体消波能力;多孔介质可以在较宽的环境压力(0.0001~1 atm)内保持良好的消波能力。

Generated during the operation of the maglev flight tunnel and reflected at the end of the tunnel,the compression wave may collide with the model at the test section and interfere with the test results.In order to attenuate the influence of compression wave during the tunnel test,the method of laying porous media inside the tunnel pipe is used to reduce the intensity of the compression wave.According to the existing porous media pressure drop equation,the equations describing the compressional wave pressure drop law through porous media in the tunnel pipe were derived.The parameters on which the wave elimination ability of porous media in the equation depend were analyzed by numerical simulation.The results show that the porous media has the same proportion of the pressure drop effect on the compression wave within different strengths.Its wave elimination ability increases with the increase of the compression wave strength,inertial resistance coefficient and porous media thickness.However,with the increase of the inertial resistance coefficient and thickness,a part of the compression wave is reflected instead of passing through the porous media.The strength of the reflected compressional wave also increases with the increase of the inertial resistance coefficient and thickness.Dividing the porous media into multiple layers can reduce the strength of the reflected compressional wave while other parameters of the porous media remain unchanged,so as to improve the overall wave elimination ability of the porous media.Porous media could maintain favourable wave elimination ability under a wide range of ambient pressure changes(0.0001-1 atm).