Numerical Simulation of Jet Noise

Author:

Paliath, Umesh

Graduate Program:

Aerospace Engineering

Degree:

Doctor of Philosophy

Document Type:

Dissertation

Date of Defense:

December 21, 2005

Committee Members:

Philip John Morris, Committee Chair/Co-Chair
Dennis K Mc Laughlin, Committee Member
Kenneth Steven Brentner, Committee Member
Victor Ward Sparrow, Committee Member

Keywords:

Large eddy simulation
Detached eddy simulation
Jet noise

Abstract:

In the present work, computational aeroacoustics and parallel computers are used to conduct a study of flow-induced noise from different jet nozzle geometries. The nozzle is included as part of the computational domain. This is important to predict jet noise from nozzles associated with military aircraft engines. The Detached Eddy Simulation (DES) approach is used to simulate both the jet nozzle internal and external flows as well as the jet plume. This methodology allows the turbulence model to transition from an unsteady Reynolds Averaged Navier-Stokes (URANS) method for attached boundary layers to a Large Eddy Simulation (LES) in separated regions. Thus, it is ideally suited to jet flow simulations where the nozzle is included. Both cylindrical polar and Cartesian coordinate systems are used. A spectral method is used to avoid the centerline singularity when using the cylindrical coordinate system. The one equation Spalart-Allmaras turbulence model, in DES mode, is used to describe the evolution of the turbulent eddy viscosity. An explicit 4th order Runge-Kutta time marching scheme is used. For spatial discritization the Dispersion Relation Preserving scheme(DRP) is used. The far-field sound is evaluated using the Ffowcs Williams-Hawkings permeable surface wave extrapolation method. This permits the noise to be predicted at large distances from the jet based on fluctuations in the jet’s near field. The present work includes a study of the effect of different nozzle geometries such as axisymmetric /non-axisymmetric and planar/non-planar exits on the far field noise predictions. Also the effect of operating conditions such as a heated/unheated jet, the effect of forward flight, a jet flow at an angle of attack, and the effect of a supersonic exit Mach number, are included in the study