高压气体状态下阀口流动特性研究

发布时间：2018-06-01 11:09

本文选题：高压气动 + 充放气　；参考：《华中科技大学》2011年硕士论文

【摘要】：高压气动系统功率重量比大,相对低压系统刚度高,有较好的动态性能,有利于实现高速化和元件小型化,使气动技术有着更广阔的应用空间。然而,现有气动理论的研究主要是针对低压气动系统,对于高压气动理论的研究,缺乏相应的研究方法和完整的理论。由于高压气动系统在气体流动特性具有不同的特点,不能简单采用低压气动理论,需要从高压气体本质特性上着手,进行相应分析。本文对高压气体通过节流口的特性及固定容积容器充放气过程进行了理论和实验研究,其目的在于建立相应的高压气体运动模型,为高压电—气比例阀的研制提供理论基础。首先,运用实际气体热力学以及气体动力学方程,采用范德瓦尔状态方程对高压气体进行描述,基于不同的能量关系建立了相应的质量流量特性方程,并与理想气体质量流量特性方程进行对比分析,得到了符合实际的质量流量特性方程。在此基础上对高压容器定容积充放气过程进行分析,建立了容器内部实际气体数学模型。对此模型进行仿真,结果表明实际气体充放气过程在低压情况下与理想气体吻合较好,偏差较小,而随着气体初始压力的增加,实际气体模型和理想气体模型的差异更加明显,实际气体模型更加符合实际情况。其次,通过建立固定容器充放气模型,采用有限体积法对充放气过程进行数值模拟。结果表明:充放气过程中,放气口处气体状态变化属于等熵绝热过程,并且容器内部压力、温度场等基本是均匀分布,通过监测进出口质量流量的变化趋势上发现,理论模型仿真与数值模拟结果有着很好的一致性。最后,采用国家标准对气体通过节流口的流量特性进行实验研究,测得节流口的有效截面积及临界压力比,并运用止停法对容器内气体温度值进行测试计算。分析不同参数对充放气过程的影响,并将实验结果与高压气体充放气模型仿真结果比较,容器内压力曲线及温度曲线的实验值与实际气体模型仿真结果较符合。
[Abstract]:The high pressure pneumatic system has high power / weight ratio, high stiffness relative to low pressure system, good dynamic performance, which is helpful to realize high speed and miniaturization of components, and make pneumatic technology have wider application space. However, the existing aerodynamic theory is mainly aimed at the low-pressure pneumatic system, and the research of high-pressure pneumatic theory lacks the corresponding research method and the complete theory. Since high pressure pneumatic system has different characteristics in gas flow, it can not simply adopt low pressure pneumatic theory. It is necessary to start with the essential characteristics of high pressure gas and make corresponding analysis. In this paper, the characteristics of high pressure gas passing through throttle and the filling and discharging process of fixed volume container are studied theoretically and experimentally. The purpose of this study is to establish the corresponding model of high pressure gas movement, and to provide a theoretical basis for the development of high voltage-gas proportional valve. Firstly, using the actual gas thermodynamics and gas dynamics equation, the Van der Waals equation of state is used to describe the high pressure gas, and the corresponding mass flow characteristic equation is established based on different energy relations. Compared with the ideal gas mass flow characteristic equation, the mass flow characteristic equation is obtained. On this basis, the process of constant volume gas filling and discharging of high pressure vessel is analyzed, and the actual gas mathematical model of the vessel is established. The simulation results show that the actual gas charging and discharging process is in good agreement with the ideal gas at low pressure, and the deviation is small. With the increase of the initial pressure of the gas, the difference between the actual gas model and the ideal gas model is more obvious. The actual gas model is more in line with the actual situation. Secondly, the finite volume method is used to simulate the filling and discharging process of the fixed vessel by establishing the gas filling and discharging model. The results show that the change of gas state at the outlet is isentropic adiabatic process, and the internal pressure and temperature field of the vessel are basically uniform distribution. It is found by monitoring the change trend of mass flow in the inlet and outlet. The results of theoretical model simulation and numerical simulation are in good agreement. Finally, the flow characteristics of the gas passing through the throttle are experimentally studied by using the national standard. The effective cross section area and the critical pressure ratio of the throttle are measured, and the temperature value of the gas in the vessel is measured and calculated by the stop-stop method. The effect of different parameters on the gas filling and discharging process is analyzed. The experimental results are compared with the simulation results of the high pressure gas charging and discharging model. The experimental values of the pressure curve and temperature curve in the vessel are in good agreement with the actual gas model simulation results.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH138

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