Multivariate Statistics Analysis of the Pressure Field Induced By High-Speed Turbulent Boundary Layers

Abstract

A DNS database of turbulent boundary layers with the freestream Mach number spanning from M∞ = 2:5 to M∞ = 14 is utilized to study multivariate statistics of pressure fluctuations induced by high-speed turbulent boundary layers. The multivariate pressure statistics include pressure correlations and coherence at multiple wall-normal locations, including those within the boundary layer and in the free stream. Within the boundary layer, the extent of pressure-correlation contours increases in both streamwise and spanwise directions as the wall-normal height increases, and variations in the freestream Mach number and the wall temperature do not seem to cause substantial differences in the size of large-scale pressure structures. In the free stream, however, the acoustic pressure structures exhibit a significant reduction in spatial length scales and the structure angle as compared with those in the outer region of the boundary layer, and the pressure wave front is found be significantly shallower as Mach number increases. For all wall-normal locations, the coherence of pressure fluctuations attains much higher values at low frequencies and decays at high frequencies, with the spanwise coherence decaying substantially faster than the streamwise coherence. The coherence length increases with wall-normal coordinate within the boundary layer in both streamwise and spanwise directions. In the free stream, the streamwise coherence length and the Lagrangian correlation length are similar to those close to the wall, and such an apparent match indicates that the acoustic sources are located near the wall and is consistent with the 'Mach wave radiation' concept.

Meeting Name

46th AIAA Fluid Dynamics Conference (2016: Jun. 13-17, Washington, DC)

Department(s)

Mechanical and Aerospace Engineering

Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Acoustics; Aerodynamics; Atmospheric Thermodynamics; Boundary Layer Flow; Fluid Dynamics; Mach Number; Multivariant Analysis; Turbulence; Turbulent Flow; Wavefronts; Acoustic Pressures; Coherence Lengths; Correlation Lengths; Freestream Mach Number; Mach Wave Radiation; Multivariate Statistics; Pressure Fluctuation; Turbulent Boundary Layers; Boundary Layers

International Standard Book Number (ISBN)

978-1624104367

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2016 American Institute of Aeronautics and Astronautics (AIAA), All rights reserved.

Publication Date

01 Jun 2016

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