摘要水下气液两相冲压发动机有非常好的发展前景。在水下航行体高速航行时，此类发动机仍能保持性能良好，并且其有效空间以及载荷占用相对较小，同时也可以避免空化作用对发动机结构及功能的毁坏，在水下复杂的工况中有较强的适应能力。73331

此类发动机工作原理为：水从发动机入口处进入后，便经过进水道受到冲压效应，导致速度的减小以及压力的增加；水经过进水道受到冲压后便会与从喷嘴的地方喷出的高压气体相混合，从而成为气液两相混合物，此时的混合物压力是高于原来单相水的；在流经发动机内部的喷管后，原本高压的混合物其速度会提高，但压力却是减小的，在发动机入口处的混合物速度大小与其出口处的大小相比是较小的，推力便由此产生。

本文主要是对典型的水下气液两相冲压发动机进行数值模拟，主要分析对象为气液混合后的混合物流体动力学方面的特性。通过对典型的水下气液两相冲压发动机内流场的研究，并进一步分析可以得知，该结构中的气液两相混合物的流动形式是一种类似环状流，在混合室内壁以及喷管内壁面上，气体会顺着该轨迹流动最终成为环状含气区，气环中心是一条液相轴心，两相之间的分界层十分明显，同时也得到了发动机内参数的分布规律与流场通气参数的关系，以及分界层厚度与之关系的影响。若在较高流速的情况下，没有气体的喷入，此时便会有自然空化现象的产生，喷入一定量空气后该现象便不会存在。

毕业论文关键词  水下气液两相冲压发动机  通气参数  自然空化  分界层    数值模拟

毕业设计说明书外文摘要

Title   Numerical simulation of underwater two phase ramjet working process                                                           

Abstract Underwater two-phase ramjet engine has good prospects for development。 When submerged body speed sailing, these engines can still maintain good performance。 Its effective load and space is comparatively less。 In addition, it can avoid cavitation damage to the engine structure, and have a strong adaptability on underwater complex conditions。

The working theory of such engine works are as follows: when the water flow from the inlet of the engine and go through the water inlet by stamping effect, it result in speed of a pressure is increasingly reduced; when water goes through the water inlet, it will be stamped after the high pressure gas from the gas nozzle, and then mixed, thereby forming a gas-liquid two-phase mixture。 Then the pressure of the mixture is higher than the pressure of the original single-phase water; after it flows through the engine nozzle, the original speed of high-pressure mixture will increase, but the pressure is reduced, the speed of gas-liquid at the inlet of the engine two-phase mixture is less than the rate of speed at the outlet, then result thrust。

The aim of this article is to study typical underwater two phase ramjet numerical simulation, the main object of study is the fluid dynamics of gas-liquid mixing mixture。 Based on the research and analysis of the flow field in a typical underwater two phase ramjet that the structure of gas-liquid two-phase flow is in the form of a mixture similar to annular flow, the mixing chamber and the inner wall surface of the nozzle, air can flow along the track so as to form an annular gas-bearing zone, center of the ring form liquid gas axial by water, boundary layer between the two phases is very obvious, but also get the distribution of the flow within the engine parameters relations field ventilation parameters and the effect of the boundary layer thickness with relationships。 At higher flow rates if sprayed into the air, there will be a natural cavitation phenomenon, after a certain amount of air injected into the phenomenon will disappear。