Investigations of Flow Properties in an Expansion Tube

摘要

Early experimental investigations of expansion tubes, which incorporate unsteady expansions to produce high Mach number, high energy flow, have pointed to two major difficulties: (1) flow contamination; and (2) lack of flow uniformity. The tests reported, which include (1) measurements of the number densities of the major impurities Fe, CN, Cr; (2) pitot pressure measurements in conjunction with interferometric measurements of free stream density; and (3) stagnation heat transfer measurement; show that the extent of these difficulties is largely overestimated. The effect of a diaphragm cutting device for the secondary diaphragm (the uncontrolled bursting of the diaphragm is thought to be responsible for the difficulties experienced) is found to have an adverse effect on the flow properties. Preliminary results from an expansion tube with the secondary diaphragm supported by a 'nozzle plate' are, however, encouraging. (Author)