水引射蒸汽引射器的数值模拟

Numerical Simulation of Steam-water Ejector

建立了水引射水蒸汽的引射器3维数值模型,以欧拉-欧拉双流体模型为基础,结合基于热平衡的直接接触冷凝传热传质模型,对引射器内发生的两相流流动和传热传质过程进行了数值计算。考察了引射器进出口流体参数变化对引射器引射系数、升温能力的影响,同时获得了引射器内汽水分布和温度压力场的变化规律。计算结果表明,引射器引射系数随一次流压力升高而略有升高,随一次流水温的升高和被引射蒸汽压力的降低而降低;进出口温升变化规律则与引射系数相同;引射器出口背压升高导致引射系数降低,且升高至一定值时,引射器出现回流。计算所得规律与实验所得一致,表明提出的模型具有一定参考价值。

A three-dimensional steam-water ejector model where water injects steam was built. The process of two phase flow and heat mass transfer involved was investigated numerically, based on the Euler-Euler difluid model and direct contact condensing model combined with thermal phase change theory. The influences of the different boundaries conditions of ejector inlet and outlet on the entrainment ratio(ER) and heating up abilities were studied. Meanwhile, distribution of the steam-water and variation of the temperature and pressure field in the ejector were obtained. The result showed that, ER increased a bit as the primary fluid pressure increased, and decreased as the primary fluid temperature increased or the secondary fluid pressure decreased. The heating up ability between the inlet and outlet followed the same rules as the ER. The increase of ejector back pressure reduced the ER, and back flows could emerge when the back pressure increased to some value. The rules obtained here resemble other peoples' experimental result,indicating the value of the model presented in this paper.