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Full-Text Articles in Engineering
Methods For Identifying Acoustic Emissions From The Front Face Of A Small Piezoelectric Blower, Brad K. Solomon
Methods For Identifying Acoustic Emissions From The Front Face Of A Small Piezoelectric Blower, Brad K. Solomon
Theses and Dissertations
This thesis focuses on identifying acoustic noise generating components in piezoelectric blowers through transverse velocity measurements and the development of a numerical fluid model. Piezoelectric ceramics have proven useful for many industries and areas of research involving: high precision actuators, noise control, ultrasonic devices, and many other areas. As of late, a unique adaptation of piezoelectric ceramics is surfacing in the area of pumping and cooling. Air pumps that use these ceramics replace the traditional electric motor, resulting in lower power consumption, less moving parts, constant pressure gradients, lower overall weight, and a low profile. The current drawback of this …
Experimental Characterization Of Baffle Plate Influence On Turbulent And Cavitation Induced Vibrations In Pipe Flow, Gavin J. Holt
Experimental Characterization Of Baffle Plate Influence On Turbulent And Cavitation Induced Vibrations In Pipe Flow, Gavin J. Holt
Theses and Dissertations
Turbulent and cavitation induced pipe vibration is a large problem in industry often resulting in pipe failures. This thesis provides an experimental investigation on turbulent flow and cavitation induced pipe vibration caused by sharp edged baffle plates. Due to large pressure losses across a baffle plate, cavitation can result. Cavitation can be destructive to pipe flow in the form of induced pipe wall vibration and cavitation inception. Incipient and critical cavitation numbers are design points that are often used in designing baffle plate type geometries. This investigation presents how these design limits vary with the influencing parameters by exploring a …
Experimental Characterization Of Flow Induced Vibration In Turbulent Pipe Flow, Andrew S. Thompson
Experimental Characterization Of Flow Induced Vibration In Turbulent Pipe Flow, Andrew S. Thompson
Theses and Dissertations
This thesis presents results of an experimental investigation that characterizes the wall vibration of a pipe with turbulent flow passing through it. Specifically, experiments were conducted using a water flow loop to address three general phenomena. The topics of investigation were: 1) How does the pipe wall vibration depend on the average flow speed, pipe diameter, and pipe thickness for an unsupported pipe? 2) How does the behavior change if the pipe is clamp supported at various clamping lengths? 3) What influence does turbulence generation caused by holed baffle plates exert on the pipe response? A single pipe material (PVC) …
Analysis Of Induced Vibrations In Fully-Developed Turbulent Pipe Flow Using A Coupled Les And Fea Approach, Thomas P. Shurtz
Analysis Of Induced Vibrations In Fully-Developed Turbulent Pipe Flow Using A Coupled Les And Fea Approach, Thomas P. Shurtz
Theses and Dissertations
Turbulent flow induced pipe vibration is a phenomenon that has been observed but not fully characterized. This thesis presents research involving numerical simulations that have been used to characterize pipe vibration resulting from fully developed turbulent flow. The vibration levels as indicated by: pipe surface displacement, velocity, and acceleration are characterized in terms of the parameters that exert influence. The influences of geometric and material properties of the pipe are investigated for pipe thickness in the range 1 to 8 mm at a diameter of 0.1015 m. The effects of pipe elastic modulus are explored from 3 to 200 GPa. …
Numerical Simulation Of Plasma-Based Actuator Vortex Control Of A Turbulent Cylinder Wake, Nathan Keith Mcmullin
Numerical Simulation Of Plasma-Based Actuator Vortex Control Of A Turbulent Cylinder Wake, Nathan Keith Mcmullin
Theses and Dissertations
A numerical study has been performed to investigate the mechanics of the turbulent wake of a circular cylinder that is controlled by a plasma actuator. The numerical investigation implements a straightforward moving wall boundary condition to model the actuator's effects on the flow. Validations of the moving wall for this simulation are set forth with the understanding that the moving wall can model the plasma actuator bulk flow effects at a distance downstream and not in a region near or on the plasma actuator. The moving wall boundary condition is then applied to a circular cylinder at a Reynolds number …
Large Eddy Simulation Based Turbulent Flow-Induced Vibration Of Fully Developed Pipe Flow, Matthew Thurlow Pittard
Large Eddy Simulation Based Turbulent Flow-Induced Vibration Of Fully Developed Pipe Flow, Matthew Thurlow Pittard
Theses and Dissertations
Flow-induced vibration caused by fully developed pipe flow has been recognized, but not fully investigated under turbulent conditions. This thesis focuses on the development of a numerical Fluid-Structure Interaction (FSI) model that will help define the relationship between pipe wall vibration and the physical characteristics of turbulent flow. Commercial FSI software packages are based on Reynolds Averaged Navier-Stokes (RANS) fluid models, which do not compute the instantaneous fluctuations in turbulent flow. This thesis presents an FSI approach based on Large Eddy Simulation (LES) flow models, which do compute the instantaneous fluctuations in turbulent flow. The results based on the LES …
A Similarity Model For Flow In A Turbulent Boundary Layer, Earl Clark Lemmon
A Similarity Model For Flow In A Turbulent Boundary Layer, Earl Clark Lemmon
Theses and Dissertations
One of the basic goals in engineering is to generate models which will provide a means for analytically predicting observed phenomenon. Such a model is often modified several times to obtain better results. The purpose of this study was to generate a model for an equilibrium turbulent boundary layer for steady flow over a flat plate and compare the results obtained by using the model with experimental data. Part of the objective was to also suggest ways in which the model could be modified to obtain better results.
Transition From Laminar To Turbulent Flow For Dilute Guar Gum Solutions, Martin L. Palmer
Transition From Laminar To Turbulent Flow For Dilute Guar Gum Solutions, Martin L. Palmer
Theses and Dissertations
Solutions of many natural and synthetic polymers have been found to reduce turbulent friction losses in flow through pipes. The basic mechanism causing these reductions is not entirely understood although two general theories have been advanced.
The Aerodynamic Drag On Spheres Under Acceleration, Charles Earl Nielson
The Aerodynamic Drag On Spheres Under Acceleration, Charles Earl Nielson
Theses and Dissertations
The requirement of a greater understanding of the behavior of solids-gas systems has shown itself profoundly with the advancement of science and technology during recent years. The range and variety of processes in which these systems play an important role is exceptionally broad. These processes range from meteorological disturbances such as dust storms, rain and snow, to the use of vacuum cleaning equipment. With the advancement of aircraft and space technology the influence of these systems is again felt in such cases as the motion of rockets, missiles and aircraft in flight, the behavior of liquid droplets or metallic particles …
The Verification And Use Of A Hot-Wire Anemometer In Turbulence Measurements, Charles Young Warner
The Verification And Use Of A Hot-Wire Anemometer In Turbulence Measurements, Charles Young Warner
Theses and Dissertations
One very important part of research is the development of effective, reliable instruments. The measurement of turbulence in flow fields is a complex research problem. It depends heavily upon the hot-wire anemometer. This thesis describes the evaluation and use of a constant- current hot-wire anemometer, and presents the equations governing its use for turbulence measurements. The thesis first enumerates and explains some of the important parameters of turbulent flows, providing the basis for the discussion of their measurement which follows. The cooling of a heated wire in forced convection and a typical anemometer circuit are discussed. Derivations of the instrument …