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Title: Pressure fluctuations beneath turbulent spots and instability wave packets in a hypersonic boundary layer.

Abstract

The development of turbulent spots in a hypersonic boundary layer was studied on the nozzle wall of the Boeing/AFOSR Mach-6 Quiet Tunnel. Under quiet flow conditions, the nozzle wall boundary layer remains laminar and grows very thick over the long nozzle length. This allows the development of large turbulent spots that can be readily measured with pressure transducers. Measurements of naturally occurring wave packets and developing turbulent spots were made. The peak frequencies of these natural wave packets were in agreement with second-mode computations. For a controlled study, the breakdown of disturbances created by spark and glow perturbations were studied at similar freestream conditions. The spark perturbations were the most effective at creating large wave packets that broke down into turbulent spots. The flow disturbances created by the controlled perturbations were analyzed to obtain amplitude criteria for nonlinearity and breakdown as well as the convection velocities of the turbulent spots. Disturbances first grew into linear instability waves and then quickly became nonlinear. Throughout the nonlinear growth of the wave packets, large harmonics are visible in the power spectra. As breakdown begins, the peak amplitudes of the instability waves and harmonics decrease into the rising broad-band frequencies. Instability waves are stillmore » visible on either side of the growing turbulent spots during this breakdown process.« less

Authors:
; ;  [1]
  1. (Purdue University, West Lafayette, IN)
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
1038193
Report Number(s):
SAND2010-8879C
TRN: US201208%%334
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Proposed for presentation at the 49th Aerospace Sciences Meeting held January 4-7, 2011 in Orlando, FL.
Country of Publication:
United States
Language:
English
Subject:
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; AMPLITUDES; BOUNDARY LAYERS; BREAKDOWN; CONVECTION; DISTURBANCES; FLUCTUATIONS; HARMONICS; INSTABILITY; NOZZLES; SPECTRA; TRANSDUCERS; WAVE PACKETS

Citation Formats

Beresh, Steven Jay, Casper, Katya M., and Schneider, Steven P. Pressure fluctuations beneath turbulent spots and instability wave packets in a hypersonic boundary layer.. United States: N. p., 2010. Web.
Beresh, Steven Jay, Casper, Katya M., & Schneider, Steven P. Pressure fluctuations beneath turbulent spots and instability wave packets in a hypersonic boundary layer.. United States.
Beresh, Steven Jay, Casper, Katya M., and Schneider, Steven P. Wed . "Pressure fluctuations beneath turbulent spots and instability wave packets in a hypersonic boundary layer.". United States.
@article{osti_1038193,
title = {Pressure fluctuations beneath turbulent spots and instability wave packets in a hypersonic boundary layer.},
author = {Beresh, Steven Jay and Casper, Katya M. and Schneider, Steven P.},
abstractNote = {The development of turbulent spots in a hypersonic boundary layer was studied on the nozzle wall of the Boeing/AFOSR Mach-6 Quiet Tunnel. Under quiet flow conditions, the nozzle wall boundary layer remains laminar and grows very thick over the long nozzle length. This allows the development of large turbulent spots that can be readily measured with pressure transducers. Measurements of naturally occurring wave packets and developing turbulent spots were made. The peak frequencies of these natural wave packets were in agreement with second-mode computations. For a controlled study, the breakdown of disturbances created by spark and glow perturbations were studied at similar freestream conditions. The spark perturbations were the most effective at creating large wave packets that broke down into turbulent spots. The flow disturbances created by the controlled perturbations were analyzed to obtain amplitude criteria for nonlinearity and breakdown as well as the convection velocities of the turbulent spots. Disturbances first grew into linear instability waves and then quickly became nonlinear. Throughout the nonlinear growth of the wave packets, large harmonics are visible in the power spectra. As breakdown begins, the peak amplitudes of the instability waves and harmonics decrease into the rising broad-band frequencies. Instability waves are still visible on either side of the growing turbulent spots during this breakdown process.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2010},
month = {12}
}

Conference:
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