Research On Drive Modes And Characteristics Of High Temperature Fuel Valve

As the key component in the aero-engine control system, fuel valve (fuel regulator) is an important object for ensure the activity of aero-engine, the working performance of which straightly affected the property of the aero-engine, even the property of the aerospace craft. For this reason, it is of extremely vital practical significance to research the key technologies of the fuel valve. Based on theory analysis, numerical simulation and experimental study, the key technologies of high temperature fuel valve with valve controlled cylinder drive mode and the direct acting type are systematically, deep investigated in the thesis. According to the characteristics of the driving mode and the high ambient temperature, the influences of the geometrical structure, the materials of valve body and the flow rate of cooling fluid on the temperature rise in the hydraulic control parts are analyzed, and the methods that can be used to reduce the temperature rise in the hydraulic control parts are proposed. The control strategies and methods of the hydraulic control system are studied according to the hydraulic system structure. The control schemes that one single on/off valve and one two-way, two-position proportional valve are respectively employed in the hydraulic control parts to carry out the position control are presented, and the control methods of which are investigated, respectively. According to the control methods, the influences of partial structural parameters on system control performance are analyzed. According to the system structure and the working conditions of the valve controlled cylinder drive fuel valv, the influences of the structure parameters on the temperature sensitivity of the nozzle flapper valve are analyzed. The structural characteristic that has the smallest temperature sensitivity of the valve is presented. The drive component of the direct acting fuel valve for high-temperature environments is studied, and a new type electricity-mechanical converter which can be used in high temperature ambient is designed.The main content of each chapter is summarized as following:In chapter 1, from the development approaches of aero-engines and the applications of high temperature fuel valve, the fuel valve’s structure, functions, categories and working principle are introduced. The research progress of the fuel valve domestic and external, and the research status and problems of the key technologies for the high temperature fuel valve are discussed. The research progresses of correlation techniques such as heat-resistant materials, high-temperature seals, magnetic materials and proportion electro-magnets are intrudced. The significance, main content and critical difficulties of this thesis are presented in the end.In chapter 2, several designs of high temperature fuel valve are proposed. The designs are direct-acting fuel valve, plane-symmetry PCM (Pulse Code Modulation, PCM) fuel valve, axle-symmetry PCM fuel valve, circular opening spool direct-acting fuel valve and valve controlled cylinder drive fuel valv. The structures and working principles of them are expounded, and the feasibility, advantages and disadvantages of all designs are analyzed. By comparison and analysis, a practicable scheme is presented and the key problems need to be resolved are clear.In chapter 3, the system structure and the working principle of the fuel valve with valve controlled cylinder drive mode are introduced, and the unsolved problems of the key technologies for the fuel valve are listed. The influences of the cool fluid flow rate, the material and the geometric structure of valve body on the temperature rise in the hydraulic control parts are analyzed based on the flow field simulation.In chapter 4, the system control scheme of valve controlled cylinder drive mode fuel valve is proposed, and the control method of the system was studied. The hydraulic control part of the high temperature fuel valve with valve controlled cylinder drive mode is simplified based on the particular system structure, and the system structure and the working principle are introduced. A single on/off valve and a two-way, two-position proportional valve are employed as control valve to carry out the position control for the hydraulic control part, respectively. The control strategies under the condition of two system structures are investigated based on the theory analysis and the simulation method. The influences of the valve nominal flow-rate on the control performance in the single on/off valve controlled system are investigated, and the proximate formula for calculating the nominal flow-rate of the on/off valve is presented according to the control requirement. The experiment has been done to verify the feasibility of the control scheme with single on/off valve controlled system. The flow compensation method and PID controller are cooperated to carry out the position control in the two-way, two-position valve controlled system. The influences of partial structural parameters on system control performance are analyzed, and the required response frequency of the valve for the hydraulic system is presented.In chapter 5, according to characteristics of the high-temperature working environment, the influences of the temperature on the control valve in the hydraulic control part of valve controlled cylinder drive fuel valve are studied, and the nozzle structure with the smallest temperature sensitivity is presented. From the basic theory of fluid mechanics, the influences of the temperature on the outlet flow rate of nozzle flapper valve at different nozzle structures are analyzed with considering of the viscosity-temperature properties of the fluid by numerical simulation, and the nozzle shape with small temperature sensitivity is presented. On this basis, the influences of some structure parameters such as orifice length, orifice inlet angle, nozzle inlet angle, nozzle length and nozzle outlet bevel angle on the temperature senstivity of nozzle flapper valve are investigated.In chapter 6, according to the high temperature resistant problem of driving part in the direct acting fuel valve in the chapter 2, a new electricity-mechanical converter which can be employed in the high temperature is proposed and designed. The geometry structure of the converter is intrudced, and the working principle is expounded with the magnetic circuit analysis method. The static and dynamic characteristics of the converter are analyzed through the finite element simulation method. The principle, composition and experimental method of the static test system and the dynamic test system are intrudced. Based on the established test table, the static and dynamic characteristics of the converter are tested. The test results indicate that the experimental results have the same trend with the finite element simulation results. Based on the static and dynamic test systems with high temperature modeling unit, the static and dynamic characteristics of the converter under different temperatures are tested. The experimental results indicate the static and dynamic characteristics the electricity-mechanical converter designed in this thesis have a slight variation with temperature.In chapter 7. all achievements of the dissertation are summarized and the further research work is presented.