Accession Number : ADA289471

Title :   Analysis of Hypersonic Boundary Layer Second Mode Instability Over a 7 deg Cone.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Dennery, Richard A.

PDF Url : ADA289471

Report Date : DEC 1994

Pagination or Media Count : 93

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.

Descriptors :   *TURBULENT FLOW, *BOUNDARY LAYER TRANSITION, *HYPERSONIC VELOCITY, *HYPERSONIC FLOW, REMOVAL, DATA TRANSMISSION SYSTEMS, THESES, POWER SPECTRA, SIGNALS, DATA REDUCTION, DATA ACQUISITION, MACH NUMBER, FREE STREAM, SPECTRUM ANALYSIS, LAMINAR FLOW, HISTOGRAMS, CONICAL BODIES, INSTABILITY, REYNOLDS NUMBER, WAVES.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE