Aerodynamic and aeroacoustic estimations of oscillatory supersonic flows
Aerodynamic and aeroacoustic estimations of oscillatory supersonic flows
Supersonic cavity flows and over-expanded round jets develop large scale instabilities which characterise the aerodynamic near-field, leading to large amplitude aerodynamic pressure fluctuations, pressure drag, and far-field noise radiation.
A joint computational fluid dynamic and aeroacoustic method was developed to study the physics of the unsteady high Reynolds number flows. The investigation aimed to resolve the large scale time dependent structures in a two-dimensional cavity flow and an over-expanded axisymmetric jet. The turbulent flow-field was modelled by the discrete short-time averaged Navier-Stokes equations with a κ — ω turbulence model. An approximate Riemann solver was used to evaluate the inviscid fluxes which were integrated in time with the viscous fluxes by a multi-step Runge-Kutta time stepping scheme. The instantaneous and time averaged flow solutions provided the source terms in a first attempt to estimate the far-field acoustic pressure using the Lighthill acoustic analogy.
The proposed numerical model produced predictions of mean and time-dependent flow fields, in good agreement with concilable model experimental measurements. The predicted mean flow features included shear layer growth, surface pressure, pressure drag, and shock cells. The time-dependent flow prediction produced the short-time averaged flow evolution, indicating the development of the dominant instability modes.
The coupled numerical method was used to study the far-field noise from the large scale structures. Areas of large momentum flux fluctuations were identified. The far-field noise predictions, including sound pressure level, directivity and spectra, produced qualitative agreement with the measured values.
Following the study of flow physics, methods were proposed to suppress the flow oscillation, through geometry modification in the cavity flow study. Significant reductions in pressure fluctuations were observed.
University of Southampton
1997
Rona, Aldo
(1997)
Aerodynamic and aeroacoustic estimations of oscillatory supersonic flows.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Supersonic cavity flows and over-expanded round jets develop large scale instabilities which characterise the aerodynamic near-field, leading to large amplitude aerodynamic pressure fluctuations, pressure drag, and far-field noise radiation.
A joint computational fluid dynamic and aeroacoustic method was developed to study the physics of the unsteady high Reynolds number flows. The investigation aimed to resolve the large scale time dependent structures in a two-dimensional cavity flow and an over-expanded axisymmetric jet. The turbulent flow-field was modelled by the discrete short-time averaged Navier-Stokes equations with a κ — ω turbulence model. An approximate Riemann solver was used to evaluate the inviscid fluxes which were integrated in time with the viscous fluxes by a multi-step Runge-Kutta time stepping scheme. The instantaneous and time averaged flow solutions provided the source terms in a first attempt to estimate the far-field acoustic pressure using the Lighthill acoustic analogy.
The proposed numerical model produced predictions of mean and time-dependent flow fields, in good agreement with concilable model experimental measurements. The predicted mean flow features included shear layer growth, surface pressure, pressure drag, and shock cells. The time-dependent flow prediction produced the short-time averaged flow evolution, indicating the development of the dominant instability modes.
The coupled numerical method was used to study the far-field noise from the large scale structures. Areas of large momentum flux fluctuations were identified. The far-field noise predictions, including sound pressure level, directivity and spectra, produced qualitative agreement with the measured values.
Following the study of flow physics, methods were proposed to suppress the flow oscillation, through geometry modification in the cavity flow study. Significant reductions in pressure fluctuations were observed.
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Published date: 1997
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Local EPrints ID: 463015
URI: http://eprints.soton.ac.uk/id/eprint/463015
PURE UUID: 835ca295-43a3-4c77-9cd6-655319072f20
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Date deposited: 04 Jul 2022 20:37
Last modified: 04 Jul 2022 20:37
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Author:
Aldo Rona
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