A new technique for the study of test time and rarefaction wave effects in hypersonic shock tubes

A knowledge of test time in shock tubes is important. Calculated values are unreliable because of the large role played by non-ideal effects such as turbulent flow through the opening diaphragm and by boundary layer phenomena. Moreover, in the case of combustion-driven and arc-driven shock tubes the driver gas state is usually only poorly known. For these reasons the test time must be evaluated experimentally. The author has developed a technique which employs a smear camera to measure the test time. The technique also provides a method for determining that regime of shock tube operation where the rarefaction wave reflected from the driver section plays a dominant role.