Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 34 for “"low Mach number"”.
-
The aeroacoustics response and shear layer dynamics of confined cavities subject to low Mach number turbulent flow
Cavities exposed to low Mach number flow in various engineering applications are often liable for generating flow-excited acoustic oscillations, resulting in large acoustic amplitudes and vibrations. This compromises the safety and reliability of critical equipment due to a phenomenon attributed to …
-
Large eddy simulation of acoustic propagation in turbulent flow through ducts and mufflers
… solver is developed and validated for a low Mach number flow simulation of acoustic pulse. This new solver is developed using C++ based OpenFOAM toolkit and further tested for low Mach number flow test case. The analysis of simple expansion muffler for various structures, frequency ranges …
-
Computation and control of flow-induced noise behind a circular cylinder using an acoustic analogy approach
… computers and reliable algorithms have allowed the prediction of far-field noise through the use of Computational Fluid Dynamics (CFD) data as near-field sound sources. One of the most useful analytical methods, used for the computation of noise, is Lighthill's acoustic analogy. The latter …
-
Sensitivity analysis of low-density jets and flames
… Direct numerical simulation (DNS) using a Low-Mach-number formulation of the Navier–Stokes equations is used to calculate direct-linear and adjoint global modes for axisymmetric low-density jets and lifted jet diffusion flames. The adjoint global modes provide a map of the most sensitive …
-
Time-resolved stagnation temperature and pressure measurements in the vortex street behind a cylinder
… temperature is nonuniform around vortices. For low Mach number flows, the instantaneous total pressure was also shown to become nonuniform in such a similar manner that the near-wake patterns of instantaneous total pressure exhibit almost exact facsimiles of these of total temperature. Here, the …
-
Etude expérimentale des sons auto-entretenus produits par un jet issu d'un conduit et heurtant une plaque fendue
… of self-sustained tones (up to 125 dB) by a low Mach number free plane jet impinging on a slotted plate, known as slot-tone, is experimentally studied. For all geometries of the slot’s edge tested, the tones are generated from 6 m/s and when a resonant mode of the duct from which the jet …
-
Quasi-optimal steady state and transient maneuvers with and without thrust vectoring
… greatest effect of thrust vectoring occurs at low Mach number.
-
Direct numerical simulation of droplet-laden isotropic turbulence
… method for simulating incompressible two-fluid flows. The method's main advantage is that the variable coefficient Poisson equation that arises in solving the incompressible Navier-Stokes equations for two-fluid flows is reduced to a constant coefficient equation. This equation can then be solved …
-
Efficient simulation of molecular gas transport for micro- and nanoscale applications
… are characterized by non-vanishing Knudsen numbers, preventing simple analyses based on the Navier-Stokes equations; and also by small departures from equilibrium (low Mach number, small temperature gradients, etc.), which make the traditional particle methods like the direct simulation …
-
Three-dimensional viscous hypersonic flows over general bodies using shock-layer and parabolized Navier-Stokes equations
The three-dimensional viscous hypersonic flowfield over blunted cones at large angles of attack, including crossflow separation, has been solved using both viscous shock-layer (VSL3D) and parabolized Navier-Stokes equations (PNS). The viscous shock-layer equations have been used for the solution of …
-
Empirical aspects of a Mini-Helicon Plasma Thruster Experiment (mHTX@MIT)
… (SPL) vacuum chamber. This experiment allows study of the intrinsic advantages of efficient helicon plasma production for use in space electric propulsion. Historical helicon experiment data have been applied to help size the experiment. The goal was to create a robust and flexible …
-
Numerical Simulations and Studies on Round Jet Impingement, Twin Jet Impingement and Helicopter Rotor Blades Ground Effect
… jet impingement on water surface in the range of Mach number from 0 to 0.3. Currently the studies on round jet impingement on water surface are very few. The goal of this research is to study the difference of aerodynamics and flow physics between air jet impinging on water surface and ground …
-
An Investigation of Blast Waves Generated by Constant Velocity Flames
The relevant flow field parameters associated with the generation and propagation of blast waves from constant velocity flames were systematically studied through numerical integrations of the non-steady equations for mass, momentum, and energy. The flow was assumed to be that of an adiabatic …
-
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 …
-
Towards Improvement of Numerical Accuracy for Unstructured Grid Flow Solver
… and quartic polynomials composed of both flow variables and their gradients. The high order flux is then calculated using the concept of MUSCL (Monotone Upstream-centered Schemes for Conservation Laws) approach. In order to maintain the accuracy for the finite volume scheme, an innovative …
-
Acceleration Techniques for Industrial Large Eddy Simulation with High-Order Methods on CPU-GPU Clusters
… to accurately and reliably predict turbulent flows with significant regions of separation. Scale-resolving simulations such as large eddy simulation (LES) are increasingly utilized with more complex problems such as flow over high lift configurations and through aircraft engines. The present …
-
A study of compressibility effects on laminar, unsteady flow past a two-dimensional bluff body
… of compressibility on the laminar, unsteady flow past a two-dimensional bluff body. The study was performed by solving the governing equations of fluid motion. The set of integral-differential equations which govern the fluid motion were approximated by a finite volume discretization. A fifth …
-
Sensitivity analysis and optimization in low order thermoacoustic models
… to system parameters can be obtained at a low computational cost. This information is used as an input to an optimization routine to find stable thermoacoustic configurations. In this thesis thermocaoustic oscillations are analysed using a linear low order network model. This modelling …
-
Sound from Rough Wall Boundary Layers
Turbulent flow over a rough surface produces sound that radiates outside the near wall region. This noise source is often at a lower level than the noise created by edges and bluff body flows, but for applications with large surface area to perimeter ratios at low Mach number, this noise source can …
-
Normalization of Roughness Noise on the Near-Field Wall Pressure Spectrum
… can be a significant contributor of sound in low Mach number, high Reynolds number flows. Only a small amount of experimental research has been conducted to analyze roughness noise because of its often low energy levels that are hard to isolate even in a laboratory setting. This study details …
Page 1 of 2