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

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).