Book Description

The driver-reservoir method of extending the test time of a tailored hypersonic shock tunnel by using a reservoir and a nozzle (perforated plate) at the upstream end of the driver is treated theoretically. It is shown that the flow following the rupture of the diaphragm is highly complex and contains both steady and unsteady flow regimes. It is also shown that the area ratio of the nozzle separating the driver from the reservoir determines the nature of the wave system produced. For a unique or 'ideal' nozzle area ratio a flow system is produced which contains no downstream running disturbances other than Mach waves. That is, both the head and the tail of the initial rarefaction wave are prevented from interfering with the shock-tunnel reservoir. Consequently, the running time of the shock tunnel can be extended. The ideal area ratios are calculated for a wide range of shock tunnel operating conditions and compared with experimental results. The comparison shows that the ideal nozzle area ratio can be predicted accurately from theory. (Author).