Date of Award

12-1994

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Rodney Bowersox, PhD

Abstract

This paper presents the results of the analysis of Mach 8.0 flow over a seven degree half-angle cone. The purpose of this analysis was to develop techniques to examine boundary layer transition at hypersonic velocities. The specific objectives were to look for second mode instability waves characteristic of the transition process and to quantify the percentage of turbulent flow. Two sets of data were used in this analysis. The first set of data was taken at several axial positions at a freestream Reynolds number 4.265 million per meter. This data was used to develop the analysis techniques. The second set of data was taken at station 35 for Reynolds numbers of 3.28, 3.94,4.92, and 6.56 million per meter. Spectral analysis was used to identify 2nd mode disturbances, if they existed. The energy associated with the disturbances was then removed from the data signal to produce a new signal. The new signal was then evaluated using conditional sampling techniques. Additional methods used to assess turbulent intermittency were histogram analysis and examination of the power spectrum of the data signal. It was determined that removal of the disturbances from the raw data signal produced a cleaner signal. However, the new signals were not amenable to conditional sampling techniques. The histogram analysis proved to be inconclusive. Examination of the power spectrum showed that a laminar flow could be identified by the presence of a strong peak corresponding to the 2nd mode disturbances, but could not be used to identify a flow as being turbulent by the absence of this peak.

AFIT Designator

AFIT-GA-ENY-94D-20

DTIC Accession Number

ADA289471

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