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Electronic Theses and Dissertations

Cavitation

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Numerical Simulations Of Cavitation In The Oil Pump And Thin-Fluid-Bearing For Automotive Applications, Jiaqi Xu Jan 2022

Numerical Simulations Of Cavitation In The Oil Pump And Thin-Fluid-Bearing For Automotive Applications, Jiaqi Xu

Electronic Theses and Dissertations

The cavitation in hydraulic pumps and fluid bearings could cause system instability, wearing, and failure. Modern commercial computational fluid dynamics (CFD) solvers such as Simerics Inc and GT-Suite have the capabilities of predicting cavitation. However, the fidelity and accuracy of those models require further evaluation. The aim of the thesis is to develop a methodology to improve the analysis of oil flow and cavitation in the oil circuit. The research project is conducted jointly by the University of Windsor and Politecnico di Torino. 3D CFD models of the vane pump and journal bearing are simulated using Simerics Inc to evaluate …


Cavitation In Vial Drop Subjected To Mechanical Shock, Houman Babazadehrokni Nov 2014

Cavitation In Vial Drop Subjected To Mechanical Shock, Houman Babazadehrokni

Electronic Theses and Dissertations

Cavitation is a phenomenon that occurs when the local pressure falls down below the critical pressure. Previous work from the Randolph lab demonstrated that protein aggregates can form when a vial of therapeutic solution is dropped onto a hard surface. The process by which this occurs is most likely shock induced cavitation. During this process, hot spots can be created with temperatures and pressures reaching thousands of Kelvin and hundreds of atmospheres, respectively, leading to degradation of protein therapeutics. This work will extend previous efforts by exploring differences generated by change in vial materials, solutions, drop methods and fill volumes. …


A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart Jan 2013

A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart

Electronic Theses and Dissertations

In the combustion zone of industrial- and aero- gas turbines, thermomechanical fatigue (TMF) is the dominant damage mechanism. Thermomechanical fatigue is a coupling of independent creep, fatigue, and oxidation damage mechanisms that interact and accelerate microstructural degradation. A mixture of intergranular cracking due to creep, transgranular cracking due to fatigue, and surface embrittlement due to oxidation is often observed in gas turbine components removed from service. The current maintenance scheme for gas turbines is to remove components from service when any criteria (elongation, stress-rupture, crack length, etc.) exceed the designed maximum allowable. Experimental, theoretical, and numerical analyses are performed to …


Cavitation In Pharmaceutical Manufacturing And Shipping, Donn Sederstrom Jan 2013

Cavitation In Pharmaceutical Manufacturing And Shipping, Donn Sederstrom

Electronic Theses and Dissertations

Therapeutic proteins are used to successfully treat hemophilia, Crohn's Disease, diabetes, and cancer. Recent product recalls have occurred because of sub-visible particle formation resulting from the inherent instability of proteins. It has been suggested that particle formation is associated with late stage processing steps of filling, shipping, and delivery. Previous work at the University of Denver demonstrated that fluid cavitation can generate a large number of sub-visible protein particles in ultra clean formulations, but that mitigation can be achieved with fluid property manipulation. The goal of this research was to (1) assess the risk of cavitation under common pharmaceutical manufacturing …


The Effect Of Static Pressure On The Inertial Cavitation Threshold And Collapse Strength, Kenneth Bryan Bader Jan 2011

The Effect Of Static Pressure On The Inertial Cavitation Threshold And Collapse Strength, Kenneth Bryan Bader

Electronic Theses and Dissertations

The amplitude of the acoustic pressure required to nucleate a gas and/or vapor bubble in a fluid, and to have that bubble undergo an inertial collapse, is termed the inertial cavitation threshold. The hydrostatic dependence of the inertial cavitation threshold was measured up to 30 MPa in ultrapure water using a high quality factor spherical resonator. The threshold increased linearly with the hydrostatic pressure and was found to be temperature dependent. The strength of the bubble collapse at the threshold was measured in terms of shock waves and light emissions. The shock amplitudes increased linearly with the hydrostatic pressure, while …