Simulation And Analysis Of Water Hydraulic Servo Valve Driven By Diphase Oppositing GMA

With the development of food processing, pharmaceutical industry, steel industry, nuclear industry, fire engineering, shipping, offshore industry, geological drilling and environmental sanitation, demands on safety, purity and environmental protection become higher and higher. Therefore, water hydraulic servo control technology has become an important research direction all over the world. As the core component of water hydraulic servo control system, the performance of water hydraulic servo valve is directly related to the property of the whole system. Water hydraulic servo valve includes a series of throttles, such as flapper-nozzle valve, annular gap and slide valve. In order to develop high-performance water hydraulic servo valve, it's necessary to investigate and analyze the flow characteristics of these throttles, especially the flow-pressure characteristics and cavitations.With the characteristics of narrow bandwidth, low energy density and low resolution, traditional servo valve which uses torque motor as the actuator cannot satisfy the requirements of modern industry. Giant Magnetostrictive Actuator (GMA), based upon Giant Magnetostrictive Material (GMM), has the characteristics of high frequency response, high reliability and high precision. With GMA as the actuator of water hydraulic servo valve, a new type of water hydraulic servo valve driven by diphase oppositing GMA is proposed.Based upon the theory of hydraulic resistance and hydraulic full-bridge, B+B type hydraulic full-bridge is designed for the water hydraulic servo valve, in which the annular gap is used as the fixed hydraulic resistance and the flapper-nozzle is the variable one. Traditional and special B+B type hydraulic full-bridge are proposed, furthermore, their characteristics are investigated and compared. At last, the hydraulic full-bridge used in water hydraulic servo valve is defined and utilized to instruct the design of water hydraulic annular gap and flapper-nozzle.The flow characteristics of the typical throttles in water hydraulic servo valve are numerically investigated with CFD technology, and then the distribution and change rules of velocity, pressure, turbulence energy and vapor volume in the whole flow field are obtained. According to the design parameters of water hydraulic servo valve, the structure parameters of slide valve, annular gap and flapper-nozzle are defined through comparisons and analyses of simulations results. The corresponding design theory and method of these throttles are proposed, and the manufacturing technology is discussed. The operation interval of the flapper is figured out according to load characteristics of the water hydraulic full-bridge and relative parameters of the water hydraulic slide valve. The study of flow-pressure characteristics show that the water hydraulic flapper-nozzle can work well as the variable hydraulic resistance in the full-bridge. FLUENT software is used to investigate the change law of the hydraulic resistance of the water hydraulic annular gap and the influence of machining errors on the flow field. The influence of spool rated travel on the hydraulic resistance is also studied. By comparison with the variable hydraulic resistance on the same half-bridge, the results show that the hydraulic resistance of the annular gap is relatively fixed.The output force and displacement of the actuator are figured out based upon the structural and mechanics analyses of the actuator and the sping tube. Then the diphase oppositing GMA is designed according to the magnetostrictive effect and prestress effect of GMM, and the maximum output force and the force corresponding to the biggest output displacement are checked. The design theory and method of the diphase oppositing GMA is proposed.