| The scramjet engine uses the method of regenerated active thermal protection during its working. The temperature of the fuel can reach 400～600℃before it flows into the combustion chamber. How to control the flow-rate of high temperature fuel accurately is quite important for the working stability of scramjet engine. In this paper, a pneumatic high-temperature flow-rate control valve is developed to control the fuel supply for scramjet engine. The valve has a good quality of sealing and can control the flow-rate of high-temperature fuel accurately. The structure and working pinciple of the valve are introduced, meanwhile its property of flow-rate control is researched. As the valve is working at high temperature, the thermal expansion will lead to distortion inside the valve body, which will distroy the working stability of the valve and influence its accuracy, speed of flow-rate control. In this paper, based on the platform of ANSYS software, the method of multi-field coupling is used to analyze the thermodynamic characteristics of the valve. From the simulation results, the temperature distribution, thermal strain and thermal stress inside the valve body are obtained. By analyzing the forces applied on the spool of the valve, the mathematic model of displacement closed-loop control is constructed. The dynamic response characteristics of displacement closed-loop control are simulated based on the Matlab/Simulink platform. From the simulation resluts, the speed, bandwidth and maximum overshoot of dynamic response can be calculated.The experiment on flow-rate control of the valve has been done in order to get its real performance. The flow-rate control system is constructed. The dynamic response characteristics of displacement closed-loop control are tested as the temperature of the fuel reaches 400℃. Meanwhile, the temperatures of the key points on valve-body surface are measured during the transient process of heat transfer. By comparing the simulation results with the experiment results, it can be seen they mainly coincide with each other. Therefore, the simulation results are proved to be dependable. The thermodynamic characteristics provide a theoretical basis for the valve to select its material and improve its structure. The flow-rate control property of the valve can be concluded from the dynamic response characteristics of displacement closed-loop control. |
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