论文部分内容阅读
针对气动真空系统中容腔的压力响应,以往的经验方法没有研究温度变化带来的影响。而在真空发生器回路的容腔抽吸过程中,容腔内空气温度的变化会对压力响应曲线产生影响。本文围绕真空发生器回路和具有一定容积的抽吸容器,改进经验方法,建立了考虑热传递的真空抽吸模型。为了研究真空抽吸过程中传热系数,使用间接测量法(“停止法”)测得了容腔内温度的变化量,得出了无量纲努塞尔数随抽吸时间的变化曲线。以等温容器抽吸法获得的真空发生器流量特性为基础,使用定努塞尔数传热模型对真空容腔压力响应进行了仿真。通过比较仿真和实验结果可知,考虑热传递的真空容腔压力响应模型能较好地表示真空容腔内压力的变化。
For the pressure response of the cavity in a pneumatic vacuum system, past empirical methods have not studied the effects of temperature changes. In the vacuum generator circuit in the cavity of the suction process, the change in the temperature of the air chamber pressure will have an impact on the pressure response curve. This article focuses on the vacuum generator circuit and a certain volume of the suction container, to improve the experience and to establish a vacuum suction model considering the heat transfer. In order to study the heat transfer coefficient during vacuum pumping, the change of temperature in the cavity was measured by indirect measurement (“stop method”), and the curve of non-dimensional Nusselt number with the pumping time was obtained. Based on the flow characteristics of the vacuum generator obtained by the isothermal container aspiration method, the pressure response of the vacuum chamber was simulated by using the constant Nusselt heat transfer model. By comparing the simulation results with the experimental results, it can be seen that the pressure response model of the vacuum chamber considering the heat transfer can better represent the change of the pressure in the vacuum chamber.