Experimental study of shock wave strengthening by a positive density gradient in a cryogenic shock tube

Citation

Rupert, Viviane Claude (1973) Experimental study of shock wave strengthening by a positive density gradient in a cryogenic shock tube. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ZXBM-7809. https://resolver.caltech.edu/CaltechTHESIS:08272010-083731520

Abstract

An experimental investigation of the strengthening of a shock wave propagating through an isobaric region of increasing density is presented. A new experimental configuration consisting of a pressure-driven shock tube mounted vertically with the test section partially immersed in a cryogenic bath is used. The resulting test gas density distribution consists of a uniform region of low density near the shock tube diaphragm, then a strong local gradient followed by another uniform region of high density. The Mach number of the shock initiated at the diaphragm is determined as the shock emerges from the gradient from velocity and temperature measurements for various initial conditions. The experimental data are compared with predictions from approximate theoretical models and a numerical integration of the exact flow equations for the shock-gradient interaction. The measured Mach numbers are considerably higher than these predictions indicating that the models are not adequate to represent the experimental configuration. Calculations show that the additional strengthening of the shock results from multiple interactions between waves generated within the gradient and flow nonuniformities due to the shock formation mechanism.

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