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Showing 1 to 20 of 97 for “"aeroacoustics"”.
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Numerical techniques for computational aeroacoustics
… noise is considered following the Computational Aeroacoustics approach which is based on direct numerical simulation of the sound field. In the region of sound generation, the unsteady airflow is computed separately from the sound using Computational Fluid Dynamics (CFD) codes. Overlapping this …
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Aeroacoustics Applications to Jets and Rotors
<p>Aeroacoustics plays a critical role in the advancement of propulsion technologies for both conventional and emerging aerial systems. This dissertation investigates two key topics: noise suppression in supersonic rectangular jets and rotor noise characterization in hover and ground effect. Using …
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Adaptive mesh refinement for computational aeroacoustics
… ADAPTIVE MESH REFINEMENT FOR COMPUTATIONAL AEROACOUSTICS by Xun Huang<br/>This thesis describes a parallel block-structured adaptive mesh refinement (AMR) method that is employed to solve some computational aeroacoustic problems with the aim of improving the computational efficiency. AMR …
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Defect correction methods for computational aeroacoustics
… is extended to the area of Computational Aeroacoustics (CAA) where sound waves generated by the pressure fluctuations are typically several orders of magnitude smaller than the pressure variations in the main flow field that accounts for flow acceleration. A decomposition of variables is …
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Aerodynamics and aeroacoustics of flap side-edges
… carried out to determine the aerodynamics and aeroacoustics of a flap side-edge. A porous side-edge treatment was applied to the flap side-edge in an attempt to reduce airframe noise. Measurements taken as part of the experimental study were forces, on-surface pressures, particle image …
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Slat aerodynamics and aeroacoustics with flow control
This study primarily investigated the flow and aeroacoustics associated with the slat of a three-element aerofoil in approach conditions. The study assessed importance of several factors and examined their aerodynamic impacts. The factors investigated were aerofoil incidence, slat angle, slat cusp …
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A multidomain spectral method for computational aeroacoustics
This thesis presents a method for computational aeroacoustics, primarily aimed at computing sound propagation in, and radiation from, turbofan inlets. The physics of sound propagation is modeled by the system of partial differential equations that describe conservation of mass, momentum and energy …
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Aeroacoustics of the bifurcated 2D supersonic inlet
An investigation was performed to determine the aerodynamic and acoustic performance of the bifurcated 2D supersonic inlet during takeoff and approach flight conditions, and to compare these results indirectly to those of the axisymmetric supersonic inlet. The comparison is not direct since the …
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Analysis of Two-point Turbulence Measurements for Aeroacoustics
Simultaneous two-point three-component four-sensor hot-wire velocity measurements taken in three flows of aeroacoustic interest are here analyzed. The analyses provide information on the turbulence structure of the flows as it would be encountered by hypothetical noise producing blades passing …
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A source-extraction based coupling method for computational aeroacoustics
This thesis involves the computation of aerodynamically generated sound using a source-extraction based coupling approach. In the present coupling method, the unsteady aerodynamic calculation and the calculation of sound propagation are separated artificially. A set of acoustic perturbation …
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Aeroacoustics of perforated drag plates for quiet transport aircraft
Historically aircraft noise is one of the principal environmental issues for aviation. Within this context, the Silent Aircraft Initiative was launched with the objective to achieve a step-change in noise reduction compared to current practice. One of the most critical tasks in noise reduction is …
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Effect of struts on aeroacoustics of axisymmetric supersonic inlets
A study was conducted to determine the effect of strut position on the aerodynamic and acoustic performance of a supersonic inlet. The investigated inlet was a prototype 1/14 scale model of a mixed compression, axisymmetric supersonic inlet designed for the high speed civil transport aircraft. A …
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Computational aeroacoustics via linearized Euler equations in the frequency domain
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1993.
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Comparison of the aeroacoustics of two small-scale supersonic inlets
An aerodynamic and acoustic investigation was performed on two small-scale supersonic inlets to determine which inlet would be more suitable for a High Speed Civil Transport (HSCT) aircraft during approach and takeoff flight conditions. The comparison was made between an axisymmetric supersonic P …
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Aeroacoustics of Supersonic Jet Interacting with Solid Surfaces and its Suppression
<p>The noise generated by supersonic jet is of primary interest in the high-speed flight. In several flight conditions jet exhaust of the propulsion system interacts with solid surfaces. For example, jet impingement on ground for a rocket lift-off, or interactions influenced by the integration of …
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Towards a silent fan: an investigation of low-speed fan aeroacoustics
… features of the flow field. In this work, the aeroacoustics of low-speed fans are investigated using a compact mixed-flow fan as a test case. The low-speed regime is less developed compared to large-scale, high-speed machines and is increasingly relevant to applications such as micro air …
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A computational and experimental investigation into the aeroacoustics of low speed flows
The noise produced by low Mach number (M ? 0.4) laminar and turbulent flows is studied using computational and experimental techniques. The emphasis is on the development and application of numerical methods to further the understanding of noise generation and far field radiation. Numerical …
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TIME-CONSERVATIVE FINITE-VOLUME METHOD WITH LARGE-EDDY SIMULATION FOR COMPUTATIONAL AEROACOUSTICS
This thesis presents a time-conservative finite-volume method based on a modern flow simulation technique developed by the author. Its applicability to technically relevant aeroacoustic applications is demonstrated. The time-conservative finite-volume method has unique features and advantages in …
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A Computational Analysis of the Aerodynamics and Aeroacoustics of Jets with Fluid Injection
<p>A detailed numerical analysis of fluidic injection as a tool to reduce noise emission is presented here. The noise reduction strategy, developed at the Pennsylvania State University, is based on injectors that blow air into the diverging section of the nozzle to emulate the effect of interior …
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Analysis and Application of Perfectly Matched Layer Absorbing Boundary Conditions for Computational Aeroacoustics
… The idea was extended to Computational Aeroacoustics in 1996, when Hu applied the method to Euler's equations. Since that time much of the work done on PML in the field of acoustics has been specific to the case where mean flow is perpendicular to a boundary, with an emphasis on …
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