The Nozzle Reed Whistle Cavitation Characteristics Of The Cylindrical Cavity

With the rapid development of modern industry and the speed of urbanization, water pollution is more and more serious, causing many water non-recycling, thus to increase water shortages and influence on the human survival environment sustainable utilization. Therefore, seeking new methods and techniques for large flow, more pollution and complicated composition industrial pollution wastewater effectively and depth treatment were urgent, to create conditions for recycling. The physical methods for water treatment known as "green water treatment because of no secondary pollution;" The sound of cavitation physics law sets high temperature and high pressure, mechanical shearing and broken as a whole, and for the physical methods for water purification processing creates special environment. Reed whistle as acoustic cavitation generator, is one by jet injection reeds, stimulate reeds do impact to the fluid surrounding the transverse vibration and sound radiation. At the same time, because of vents changes, and reeds cavitation bubble of mechanical vibration effect will make small vacuoles difficult to merge, thereby strengthening the cavitation intensity, therefore, to study of water flow with great attention. And because it is simple in structure, durable, large quantity, small power consumption, power is convenient wait for a characteristic, in the oil emulsion, averaging function, as well as in the production of petroleum wax viscosity-decreasing effect has shown its industrial application in the effect and the huge unique vitality.From the existing literature, the application of reed whistle advanced in basic research. And applied research to specific analysis of the experimental phenomena, in the aspect of design, reed whistle only according to the empirical formula, mainly based on empirical formulas and different status of the test results and the characteristics of curve is to consider the question. In the application of basic theory, according to the relevant features of acoustic frequency and intensity of parameters, and can accurately predict, achieve more convenient for application of control research in theory, almost blank. Nearly ten years, except Cengyi Luo professor discusses the mechanism of the reeds endpoint displacement feedback, and the working characteristics of research rarely reports.In this thesis, the first in this aspect prior to the theoretical and experimental research progress were summarized, and the application of the finite element analysis of reeds again, this paper discusses the vibration of structural parameters of simulated natural frequency and vibration of reeds modal, Then use the finite volume method of computational fluid dynamics of reed whistle software Fluent cavitation intensity is studied by numerical simulation, the operation parameters and the structure of the reed whistle cavitational effect, Finally the experimental method of application of reed whistle of cylindrical nozzle acoustic properties and characteristics are analyzed and studied, and the simulation results and experimental results on its voice mechanism and the cavitation mechanism are analyzed and discussed.The mainly items are following:1. The reed whistle research progress and application are summarized and introduced.2. Finite element analysis software ANSYS to simulate the vibration of the reed to explore the length and thickness of the reed influence on the natural frequency and vibration mode. Simulation results show that:(1) When the reeds thickness and width constant, vibration frequencies of reeds decreases as the length increases; when reeds length and width were constant, vibration frequencies of reeds increases as the length increases. (2) There reed's vibration mode in various ways, and with the increase of vibration frequency, vibration mode from single mode to multi-modal changes in mutual superposition.3. The use of the finite volume method based on the computational fluid dynamics software Fluent, the cavitation flow fields in the nantilever Reed-whistle were simulated. The distribution of pressure, the distribution of turbulent kinetic energy and the distribution of velocity of the cavitation areas in the Reed-whistle were computed. The influence of operating conditions and the structure of the Reed-whistle were researched, to provide the basis for the structure optimization. Reed whistle for the structure optimization provides the basis. Simulation results show that:(1) when the reed whistle has the same size, increase of the inlet pressure can make the cavitation turbulent and the flow field velocity increase and pressure value reduced, and then strengthen cavitation intensity. (2) When the inlet pressure is constant, the distance between the nozzle and the reed influence on cavitation intensity and there is an optimal value. (3) When the inlet pressure of nozzle and the distance to the reeds of certain size, cavitation intensity increase as the ratio of nozzle length and thickness increasing.4. Through experimental method to comparatively study the acoustic characteristics of the cylindrical nozzle reed whistle. Research shows that:(1) there is an optimal value for the inlet pressure to reed whistle harmonic frequency level, not with the increase of the inlet pressure and unlimited. (2) Nozzle to the distance to break reed whistle harmonic frequency level to the effect of an optimal value, When the nozzle is very close to the reeds, increase the ratio of nozzle length and thickness, also can send a strong voice. (3) The sound frequency impacted by the size of the cylindrical cavity nozzle reed whistle, and its influence mainly depends on the ratio of length and the thickness of the nozzle. (4) The sound frequency impacted by the size of reeds. When reeds length unchanged, the vibration frequency increases as the thickness of reeds increasing, When reeds thickness unchanged, the vibration frequency increases as the thickness of reeds decreasing, and the vibration frequency variation same as the law of the theoretical simulation.5. Through experimental method to comparatively study the cavitation characteristics of cylindrical nozzle reed whistle. Research shows that:(1) there is an optimal value for the inlet pressure to reed whistle before cavitation flow field influence on cavitation strength, not increases with the increase of the inlet pressure. Turbulence intensity and relative strength of cavitation intensity depends on the vibration intensity of coupling vibration. (2) Nozzle distance to the reed whistle cavitation strength there is an optimal value. (3) Reed whistle nozzle size on the cavitation intensity of impact, with the nozzle length and the thickness ratio increases, the cavitation effect of strengthening.