【作者】 冯卫民；

【导师】 刘光临；

【作者基本信息】 武汉大学 ， 流体机械及工程， 2004， 博士

【摘要】 随着人类文明和经济的发展,管道流体输送系统越来越多,如何保证泵系统的运行安全则是人们所必须要面临的首要任务。因此水锤过程分析及安全设计越来越被人们所认识和重视。 从计算机的广泛应用至今,管道流体输送系统水锤及其防护问题的理论研究和实际应用两方面都获得了相当程度的进展,整个水锤研究体系日趋完善,研究范围也日益扩大。如何更加经济合理、科学有效地防止水锤事故,根据实际情况寻找最优的防护对策,长期以来一直是人们所必须认真对待的一个研究课题。 瞬变流的过程控制是对水锤防护理论的深入和发展。瞬变流过程是一个非常复杂且难以把握和控制的波动过程。首先水锤波本身是一个复杂波,很难将其解析简化。其次水锤波源是非恒定的,且多不单一。再者影响其传播过程的因素更是十分复杂,有些如水体的汽化等,甚至能够从本质上改变水锤波动原有的特性。 波动理论告诉我们,基于独立传播原理的波动叠加现象是波动过程的重要特征,也是基本特征之一。它的作用将会造成波动的加强或减弱。多年的研究经验告诉我们,关注和研究水锤波在其传播过程中的叠加现象对于进一步解析和把握水锤波动机理及其过程控制(水锤防护),具有较大的理论意义和实用价值。 本文第一章综述了目前泵系统水锤防护方法的类型和应用,主要有:(1)缓冲稳压法。诸如:调压塔、单向调压塔、空气阀、空气罐等;(2)泄水限压法。属于这种类型的主要有:设置旁通管、取消止回阀、水锤消除器、防爆膜等;(3)减速疏压法。如:加大管径、降低波速、增设飞轮,加大机组惯性等。(4)阀调节。泵站中目前常用的瞬态调节阀门有缓闭及快关式止回阀、两阶段关闭液控蝶阀等。 本文第二章用波的传播、叠加及相干理论来深入分析水锤波动的传播、叠加过程和干涉条件,进一步深化对瞬变流过程水锤机理的认识。从单阀调节到长管道多阀调节进行了基于水锤波动理论的最优阀调节策略及水锤控制方法的研究,发展泵系统水更多还原

【Abstract】 With the development of civilization and economic, there are more and more projects with liquid piping transportation. The key mission is how to ensure these projects’ safety, so the process analysis and safety design of water hammer is more and more being attached importance to. The analysis of the water-hammer protection provides the gist for design and material purchase and the guidance for management rules.From the time of the computer being widely applied up to the present, both the theory and application of the water hammer and water hammer protection are developed quickly. The whole research system about water hammer is being perfected, and the scale of research is being extended. It is a long time research task that how to prevent the water-hammer accident more economical and efficient and search the best countermeasure for water-hammer accident. The process control of unsteady flow is a research progress of the theory of water-hammer protection. The transient flow is a very complicated wave process, it is difficult to grasp and control. The first, water hammer is a complicated wave; it is difficult to simplify the resolution. Secondly, the water-hammer wave fountain is unsteadily and not simplex. Additionally, the factors affecting the water-hammer diffusion process (such as the gasification of water) are more complicated, these may alter the intrinsic characteristic of water hammer.The wave superposition based on wave independently transmit theory is an important and essential character of wave process. It will strengthen or weaken the wave process. From years of research experience, we know, the research about wave interference is significative on theory research and application to resolve and grasp the water hammer wave mechanism and process control (water hammer protection).The currently research actuality about pumping system water hammer protection issummarized in the Chapter 1. The mainly used protection measures are: (1) Regulating pressure as a cushion. There are many measures: simple pressure regulating tower, One-Way pressure regulating tower, air valve and air jar. (2) Discharging water to drop the pressure. There are many measures: setting sideline pipe, cancel check valve, water-hammer arrester and explode-preventing film. (3) Decelerate to evacuate the pressure. Such as: increase the pipe diameter, reduce the wave velocity and increase the unit’s inertia. (4) Valve stroking. The mainly used valve types in pump stations are: slow-closing check valve and two-stage closing fluid control butterfly valve.In Chapter 2, the theory of wave transmition, superposition and interference is used to thoroughly analyze the transmition, superposition process and interference condition of water hammer fluctuate, and deepen the cognition for the mechanism of transient water hammer. The research of valve stroking optimization problems and water hammer protection based on water hammer wave superposition theory is studied on two aspects: single-valve stroking and multi-valves stroking, it develops the pumping system water hammer protection theory and perfects the water hammer control method.In Chapter 3, based on the theory of water hammer wave superposition, in allusion to the pipe system (especially tranmition pump sytem with the long-distance pipe), problems about the transient valve stroking optimization are deeply reseached. The system carrying capacity and valve hydrodynamic characteristic are complete considered, dynamic programming models and two-layers recursion programming optimization model are built. Dynamic programming model is used to optimize the sequence of valve closing. Two-layers recursion programming optimization model is used to optimize the whole system problems (including the sequence of pump-outlet valve closing and the sequence and setting location of middle-pipe valve). For the advantage of novelty design and practicality, it is very significant for reduce the project cost and management cost.Many types wave superposition generated by valve stroking to protect water hammer is researched combined many actual projects in Chapter 2 and Chapter 3. As an example of valves stroking of pump outlet valve and pipe terminal valve, the JingKou Pump Station is researched. From this research, the water hammer protection effect using pipe terminal valve in axial-flow pumps station is validated. As an example of multi valve stroking, the JiuJiang Third Water Station is researched. From this research, the water hammer protection effect using multi valves with mid-pipe valve and pump outlet valve is validated.In Chapter 4, the first, the flow-adjustable valve is introduced. Because of adjusting flow well and being operated reliably, flow-adjustable valve is set in pipe multi valve stroking system as a mid-pipe water hammer protection valve. The author wants to control the water hammer process using the water hammer wave superposition and decompose the concentrated water hammer pressure increase to dispersive. This method is used to achieve the greatest water hammer protection effect. Valve characters and requirements is analyzed considered system stabilization and energy-saving.Based on hydrodynamics, the fluid field analysis of ring-spray type flow- adjustable is finished. The valve structure is optimized to meet the need. The multi-optimized ring-spray type water hammer arrester has many advantages: (1) smaller vortex area and faintish vortex intensity, the maximum of vortex intensity is reduced 48.2%. The vortex is controlled effectively and the noise is debased because of the vibration of vortex is controlled effectively; (2) the pressure is distributed more equality, the transition area is larger. The local stress state is improved because of the valve bearing more equable, and the valve is more secure. (3) The lowest absolute pressure is higher then water vaporizable pressure, so no vibration generated by cavitations. (4) The velocity of flow is decreased. The maximum velocity of flow is decreased 40.5%, so the length of the flow-regulating straight pipe after valve may shorten. It can enhance the valve’s adaptability to topography. (5) The losing is decreased.In Chapter 5, the ring-spray type flow- adjustable is set in the JiuJiang Water Project to calculate. It is proved that the ring-spray type flow- adjustable is reliable and feasible. It is proved that the flow- adjustable can protect water hammer efficient and be reliable.更多还原