Turbulent Statistics and Associated Acoustic Sources Near Shock Wave Shear Layer Interactions
Abstract
Supersonic jet exhaust from high performance fighter aircraft during take-off on aircraftcarriers creates high amplitude acoustic radiation in the near-field. This radiation is harmful to theairmen working in the vicinity of the flight vehicle. One dominant component of the acousticradiation is caused by the shock wave shear layer interactions present within the jet plume. Wepropose to examine the statistics of the turbulence within the shear layer and how the statistics arealtered as they propagate through the shock waves. By understanding the turbulent statistics withincompressible shear layer before and after the shock wave interaction and th"eir relation to radiatednoise, we will understand the amplification of the radiated noise from the shock wave shear layerinteracti"on. The statistics of turbulence will be examined using a new mathematical frameworkbased on a decomposition approach of the Navier#NAME?e statisticsare directly related to the acoustic radiation through a new type of acoustic analogy. The nozzleshape and the effect" of additions to the nozzle geometry, such as chevrons, directly alters thewavenumber spectra near the shocks. Using the theory of"" isotropic and anisotropic turbulence andnew basis functions of anisotropic turbulence, the two-point cross-correlation of the Navi""er-Stokesequation is written as a vector-normalized, two-point cross-correlation multiplied bycorresponding wavenumber spectra of" the structure functions. Composite structure functions ofthe field variables are adapted from canonical theory of isotropic turbulence. Anisotropic structurefunctions are found numerically by large-eddy simulation and represented through a new basisfunction. A"t the conclusion of this program, we will provide guidance regarding how to potentiallyreduce near-field noise from shocks through" slight modifications of the nozzle exit or alternativelythrough a modification of the turbulent statistics near the shock wave shear layer interactions.Perturbations of the fluid at the nozzle exit will elude to the sensitivity of the noise and turbulentstatistics. We will create a new aeroacoustic framework that directly ties the most importantturbulent statistics (those that were derive"d analytically) to the radiated noise. Most importantly,the outcome of this effort will result in new research avenues to reduce he""aring loss for US Navypersonnel. This proposal titled, ~Turbulent Statistics and Associated Acoustic Sources Near ShockWave Shear"" Layer Interactions,~ is written by the principal investigator, Assistant Professor StevenA. E. Miller, and is based at the Univers"ity of Florida Department of Mechanical and AerospaceEngineering.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 05, 2017
- Source ID
- N000141712583
Entities
People
- Steven Arthur Eric Miller
Organizations
- Office of Naval Research
- United States Navy
- University of Florida