An Analysis of the Piston Motion in a Hypersonic Gun Tunnel

A theoretical analysis and some experimental results of the piston motion in the hypersonic gun tunnel are contained in this paper. The piston motion has close effects upon the uniformity of flow at the test chamber, i.e. the fluctuation of the piston near the barrel end disturbs the pressure and makes the running time decrease. To prevent such a motion and to obtain good performance of the tunnel, the perforated plate technique has been applied. The calculation of the track of the piston motion is developed into the case with the perforated plate. On the other hand, the actual piston motion is measured by the microwave technique and it is proved that the test results agree well with the analytical results.