Testing Time and Contact-Zone Phenomena in Shock-Tube Flows

Abstract

Measurements have been made in a shock tube of the hot-flow duration, the structure of the contact front, and the nature of the mixing zone. The flow duration was obtained by spectroscopically detecting the first arrival of the driver gas, and is observed to become vanishingly small with decreasing initial driven gas pressure. These data and the data of Roshko and Duff are compared with predictions of Roshko's (laminar) theory and the numerical example of Anderson's (turbulent) theory. Agreement with the one point of Anderson's prediction is surprisingly good, while the agreement with Roshko's theory ranges from excellent to unsatisfactory. Approximations in Roshko's treatment which contribute to the lack of correlation with the data obtained in the smaller diameter shock tubes of Duff and the present work are emphasized and a formulation of the flow model is developed which better predicts the actual shock-tube flow durations.

Analytical Method of Evaluating Nonuniformities in Shock Tube Flows: Theory and Development

“…This observation provides further evidence that the method accurately predicts the primary flow behaviours, but is hampered by the contamination. In agreement with the analysis of Hooker [23], the presence of strong mixing at the contact discontinuity adds considerable uncertainties to any evaluation of the rear portions of the test slug in either the multidimensional simulation or even experiments, and so the overprediction at rear of the test slug is considered acceptable. The second source of disagreement in test time is the [10].…”

“…δ m is the mass flow thickness as defined by Hooker [23] and improved upon by Mirels [1]. u w = u s is the wall speed, which equals the speed of the reference frame (shock speed), and ρ w = P E /(RT w ) is the density along the wall, which assumes a cold wall of temperature equal to the pre-shock gas temperature.…”

“…From Hooker [23], the mass flow thickness δ m for a laminar boundary layer may be calculated by Equation 5using conditions at the wall and packet distance l from the shock, where u abs = u shock − u E :…”

Analysis of the Optimum Performance of Buffered Shock Tubes

“…The calculations are quite lengthly, but fortunately the results can be expressed as equations involving only the single independent variable " , (22) so that the following conditions must be satisfied to determine the maximum final shock strength: 0 -=0 , and…”

Measurement and Simulation of the Interface in a Low-Enthalpy Shock Tunnel

“…2 because it was postulated that higher flow speeds through the diaphragm station would generate higher mixing rates across the interface. Considering only the data by Hooker,11 there does appear to be an increase in growth rate with increasing post shock speed (as illustrated by the broken line in Fig. 2).…”