Heat flux measurement techniques over the protuberance at the hypersonic flow of Mach 7

An experimental investigation has been conducted on the aerodynamic heating caused by an object protruding from a flat plate at hypersonic flows of Mach 7. Three different experimental techniques are applied to measure the heat flux and temperature over the protuberance, using two types of hypersonic wind tunnels, namely, blowdown and impulse types. This paper presents the experimental techniques needed for use in hypersonic tunnels focusing on issues such as heat flux measurement techniques, as well as the measurement of detailed experimental data. It was confirmed that the data set agree well through the comparison of data results. A large separation region is observed in front of the protuberance with that region being very sensitive to the height of the protuberance and the length of the flat plate. These flow features affect the aerodynamic heating over the protuberance. Basically, the measured heat flux is large when the height of the protuberance is large and the length of the flat plate is long. Also, the heat flux measurements at the upper positions are larger than at the lower positions. For high protuberances, a severe jump in the heat flux is observed, from about 0.6∼0.7 of the height of the protuberances. However, when the protuberance is sufficiently short, a rise in the heat flux is rarely observed as the protuberance is submerged totally under the separation region upstream from the protuberance.