Investigation Into The Key Problems Of Water Hydraulic Control Valves

In this thesis, theoretical and experimental studies of the three kinds of water hydraulic valve are comprehensively and systemically dealt with. The test rig of cavitation performance in water hydraulic control valve is first developed interiorly with higher pressure and larger flow. The cavitation phenomenon at the orifice is investigated which is the base of water hydraulic control valve structure design, and the rule is studied which different structures influence the valve characteristic and flux coefficient. At the same time, the key problem are researched as cavitation resistance, seal technology, selected material and so on. The structural design of the water hydraulic control valve, the fabrication and the optimization of the prototype are discussed in detail, and as a result, some important and creative conclusions are achieved as follows:Some new-style structure are designed and the water hydraulic control valve prototype are manufactured. The test results show the over shoot was smaller than 30%, adjusting time was shorter than 500 ms, the control accuracy was 90.7% under 14MPa. Dynamic and static experiments show that the performance of the valves accomplished the expectation. The method are put forward which parameter are optimized from the view of flow field control. The first method is to amend the pressure distribution at the throttle orifice by increasing arc transition surface, the second method is to augment the exit diameter and the taper which can restrain the cavitation extent. The cavitation test results show that the cavitation coefficient is between 0.35 and 0.5 which is close to the value in oil system, also it show that the flux coefficient with two-stage throttle configuration is lower than the flux coefficient with one-stage throttle configuration, but its cavitation resistance is better. The test results show the orifice with sphericity or ellipse structure have preferable rigidity and stronger cavitation resistance.The main contents of this thesis could fall into seven chapters as the followings.Chapter 1 introduces the development and the present status of water hydraulic. Firstly, the definition and the characteristics of water hydraulic is introduced. Furthermore, the historical background of water hydraulic is discussed in tenns of the trends of the trends of the energy resource structure and the needs of the human sustainable development. Its content of the water hydraulic in research and difficulty are sum up. Water hydraulic has been proved successfully in entertainment facilities, food industry, paper machinery, under water tools, fire fighting, and itsapplication are illustrated. In addition, the present status of water hydraulic valve , structure types, typical representations ,the key problems are described as well as intention, meaning and measure of the thesis.Chapter 2 presents a novel apparatus to measure the cavitation . Firstly, the design idea and the design demand are introduced . The experimental apparatus and system to investigate the cavitation are described. The uncertainty in the experimental measurement was analyzed.Chapter 3 studies the performance of the cavitation resistance at the valve orifice. Water has the characteristic as higher vaporization pressure, lower compressibility and higher density. So, there are serious cavitation corrupt in water hydraulic valve, this is a very important causation result in invalidation. In order to reduce or eliminate the status, the appropriate structure design must be considered as well as the suitable material. Firstly, it is introduced which different media performance impact on cavitation erosion. Secondly, the measurement and principle are concluded which can ease or prevent cavitation erosion. Additionally, the experimental study of the valve orifice are carry through with different structure and some conclusion are obtained which can instruct the design of water hydraulic valve.Chapter 4 is about the principle of water hydraulic valve and the development of prototype. Water hydraulic valve is the key component of water hydraulic technology. The difficult problem must be conquered as erode, leakage, cavitation, impulsion, and so on. So, the structure, material, machining technology must be studied in order to manufacture the water hydraulic valve with good property. In water hydraulic valve, many novelty structure and material are adopted. Firstly, three kinds of water hydraulic valve are introduced which are developed by myself. Secondly, some conclusion are sum up about structure , machining art and material.Chapter 5 introduce optimization of the water hydraulic valves. Some parameters are obtained by designer experience in the process of water hydraulic structure design which are elective in a certain extent. The optimize design is mostly measurement to advance the water hydraulic hydraulic valve performance. The chapter develop the optimization design on the basis of aforementioned chapter. Some software are utilized to enhance reliability and efficiency including Matlab/Simulink, Amesim and Fluent. Firstly, the system simulation and flow simulation are carry through on the base of actual structure parameters. Then, the simulation results are analyzed and the parameters are optimized in order to ameliorate performance of thewater hydraulic valve.Chapter 6 studies the performance of the prototype through the experiment. Firstly, the testing rig are introduced including mostly instrument ,meter and its demarcator. Secondly, the experiment item and principle are particularized. Finally, the experiment are accomplished and the experimental results are analyzedChapter 7 is the conclusion and expectation which summarizes and concludes the thesis in many aspects including numerical analysis, system design, fabrication of the prototype, performance testing, etc. Additionally water hydraulic components future development and application are expected.