Thesis--Indian Institute of Science, Bangalore. / Includes bibliographical references.

No description available.

Th. Univ.--Math.--Paris 6, 1990. / Bibliogr. p. 195-200.

Master of Science / Department of Mechanical and Nuclear Engineering / Mohammad H. Hosni / Cavitation is a phase change process and its conversion of fluid from liquid to vapor requires pressure reduction. In this thesis, cavitation of R134a refrigerant is evaluated experimentally. This work is part of an ongoing project that seeks to develop a novel cooling cycle based on the cooling potential of the fluid during cavitation. A blowdown system was designed, built, and used for conducting the experiments. This system included a special test section containing a unique converging-diverging nozzle system designed for this investigation. In the end, cavitation was achieved by flowing the test fluid through a converging-diverging nozzle. As the fluid flows through the nozzle throat, the velocity increases while the pressure decreases and cavitation occurs when its static pressure drops below its vapor pressure. The onset of cavitation was evaluated by measuring pressure, temperature, and refrigerant flow rate, and by visualizing the flow using a high-speed video camera.

Thèse doctorat : Mathématiques Appliquées : Villeurbanne, INSA : 2005. / Thèse rédigée en anglais. Introduction en français. Titre provenant de l'écran-titre. Bibliogr. p. [271]-283.

No description available.

Thesis (M.S.)--University of Michigan, 1965.

Thesis (M.S.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 58).

Master of Science / Department of Mechanical and Nuclear Engineering / Mohammad Hosni / A typical refrigeration loop is composed of an evaporator, compressor, condenser, and an expansion valve. There are many possible refrigerants that can be used, but the physical properties of water make it ineffective in the traditional refrigeration loop. But if water could be used it would have many advantages as it is abundant, cheap, and is safe for the environment. This research focuses on a different kind of refrigeration loop using water. This new refrigeration loop utilizes water flowing through a nozzle, initiating cavitation. Cavitation is generally defined as creating vapor from liquid, not through adding heat, but by decreasing the pressure. In a converging/ diverging nozzle, as the cross sectional area is constricted, the velocity of the flow will increase, decreasing the pressure. Therefore, by flowing water through the nozzle it will cavitate. Transforming liquid into gas requires a certain amount of energy, defined as the latent heat. When a liquid is turned to vapor by an increase in the temperature, the latent heat is provided by the heat transfer to the system. As no energy is being added to the nozzle to cause the cavitation, the energy transfer to create the vapor comes from the remaining liquid, effectively causing a temperature drop. This research focused on the flow visualization of water cavitating as it travelled through a converging/ diverging nozzle. Under different flow conditions and different nozzle geometries, the cavitation manifested itself in different formations. When gasses were entrained in the water they formed bubbles, which acted as nucleation sites as they moved through the nozzle. This was called travelling bubble cavitation. In venturi nozzles the cavitation nucleated off of the wall, forming attached wall cavitation. When water flowed out of an orifice, a turbulent mixture of liquid and vapor, orifice jet, was formed which caused vapor to form around it. This was known as shear cavitation. When the water was rotated prior to the throat of an orifice, the orifice jet expanded radially and formed swirl cavitation. In addition to studying how the cavitation was formed, the void fraction and velocity were measured for attached wall cavitation.

Cavitating Flow Luminescence (CFL) is spontaneous photon emission associated with hydrodynamic cavitation which occurs when a flowing liquid passes through a Venturi.1 In this work, cavitation and micro-plasma generation in a flowing liquid, using a micro-Venturi, has been investigated. A bench-top system was designed and constructed to study CFL in a variety of liquids. The system comprised a high flow, liquid handling manifold and micro-Venturi with a variety of orifice sizes ranging from 160 – 220 μm i.d. The CFL was detected for the first time on a micro-scale using a PMT. The effect of various parameters such as temperature, flow rate (a proxy for the pressure differential) and orifice diameter were investigated to optimise the system. Studies were carried out using DDW and the effect of temperature, pressure and orifice size on CFL; it was found that low temperatures and high pressures resulted in more intense CFL. The effect of re-gassing with different noble gases was investigated and resulted in a large increase in CFL. Investigations in to the effect of solute concentration on CFL were performed using dimethylsulphoxide, polyethyleneglycol-200, isopropanol, diethyleneglycol and Triton X 100 & titanium sulphate nano-particles. Solutes with low vapour pressures resulted in an increase in CFL whereas solutes with a high vapour pressure supressed CFL, due to quenching effects. Low resolution spectra were produced using bandwidth filters to identify wavelength areas of strong emission from CFL.