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The Interaction of a Reflected Shock Wave with the Boundary Layer in a Shock Tube

Description: Ideally, the reflection of a shock from the closed end of a shock tube provides, for laboratory study, a quantity of stationary gas at extremely high temperature. Because of the action of viscosity, however, the flow in the real case is not one-dimensional, and a boundary layer grows in the fluid following the initial shock wave. In this paper simplifying assumptions are made to allow an analysis of the interaction of the shock reflected from the closed end with the boundary layer of the initial shock afterflow. The analysis predicts that interactions of several different types will exist in different ranges of initial shock Mach number. It is shown that the cooling effect of the wall on the afterflow boundary layer accounts for the change in interaction type. An experiment is carried out which verifies the existence of the several interaction regions and shows that they are satisfactorily predicted by the theory. Along with these results, sufficient information is obtained from the experiments to make possible a model for the interaction in the most complicated case. This model is further verified by measurements made during the experiment. The case of interaction with a turbulent boundary layer is also considered. Identifying the type of interaction with the state of turbulence of the interacting boundary layer allows for an estimate of the state of turbulence of the boundary layer based on an experimental investigation of the type of interaction. A method is proposed whereby the effect of the boundary-layer interaction on the strength of the reflected shock may be calculated. The calculation indicates that the reflected shock is rapidly attenuated for a short distance after reflection, and this result compares favorably with available experimental results.
Date: March 1, 1958
Creator: Mark, Herman
Item Type: Report
Partner: UNT Libraries Government Documents Department

Investigation of Aperiodic Time Processes with Autocorrelation and Fourier Analysis

Description: Autocorrelation and frequency analyses of a series of aperiodic time events, in particular, filtered noises and sibilant sounds, were made. The position and band width of the frequency ranges are best obtained from the frequency analysis, but the energies contained in the several bands are most easily obtained from the autocorrelation function. The mean number of zero crossings of the time function was determined from the curvature of the latter function in the vicinity of the zero crossing, and also with the aid of a decimal counter. The second method was found to be more exact.
Date: March 1, 1958
Creator: Exner, Marie Luise
Item Type: Report
Partner: UNT Libraries Government Documents Department

NACA Conference on high-speed aerodynamics

Description: This document contains reproductions of technical papers presented by staff members of the NACA Laboratories at the NACA Conference on High-Speed Aerodynamics held at the Ames Aeronautical Laboratory of the NACA, March 18, 19, and 20, 1958. The primary purpose of this conference was to convey to the military services and their contractors the results of recent research results and to provide those attending an opportunity to discuss the results. The papers in this document were prepared for presentation at the conference and are considered as complementary to, rather than as substitutes for, the Committee's more complete and formal reports.
Date: March 1, 1958
Item Type: Report
Partner: UNT Libraries Government Documents Department