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Title: Cavitation associated low-frequency fluctuation
Author: Li, Shengcai
ISNI:       0000 0001 2419 6050
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1990
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This self-guided thesis presents the research results of the Cavitation Associated Low-frequency Fluctuation, i. e. one part of the long-term research project on Statistical Characteristics of Cavitation Bubble Collapse Pulses. Associated Low-frequency Fluctuations and Flow Noise which was initiated and carried out by the author in USA. China and UK successively over last 9 years. The background and the objectives of the long-term project is introduced in the thesis through a broad review of the development of the cavitation research in the fields relevant to the project. Then, the observed phenomenon of Cavitation Associated Low-frequency Fluctuation in the venturi cavitating flow of the University of Michigan ( USA ) is explained in detail. A one-dimensional linear physical model based on the theorem of the interaction between the cavitation cloud of the homogeneous liquid-vapour/gas mixture and the surrounding liquid portion in the flow system is proposed to describe the mechanism of the phenomenon. The appearance of this low-frequency fluctuation is an association nature of the cavitating flow, which could be regarded as an alternatively indirect indicator of cavitation inception especially in such sort of cavitating flow systems. When the natural frequencies for both the cavitation cloud and the surrounding liquid portion coincide, the low- frequency pressure fluctuation component reaches its maximum, which is defined as Cavitation Resonance. A numerical verification of the frequency response characteristics, using the hydraulic impedance approach, of this venturi system is presented as well. The knowledge of the cavitation associated low-frequency fluctuation acquired from the study of the venturi cavitating flow has been used to analyze the phenomenon of the pressure fluctuations associated with the cavitating flows in the hydraulic machinery systems such as the HL-160-25 ( Francis ) Hydraulic Turbine System (draft-tube cavitating flow). The results are also briefly presented.
Supervisor: Not available Sponsor: National Science Foundation (U.S.) ; University of Michigan ; Guo jia zi ran ke xue ji jin wei yuan hui (China) ; North China University of Water Resources and Electric Power ; Science and Engineering Research Council ; University of Warwick
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TA Engineering (General). Civil engineering (General) ; TJ Mechanical engineering and machinery