圆管沟槽结构参数对气幕形成和排水特性的影响

Effects of Structural Parameters of Grooves on Gas Curtain Formation and Drainage Characteristics

关键词:  水下火炮  气幕式发射  气-液相互作用  多股燃气射流  排水特性

Key words:  Underwater gun  Gas-curtain launching  Gas-liquid interactions  Multi-combustion gas jet  Drainage characteristics

摘要:

为提高全淹没式水下火炮弹丸的发射初速，基于气幕式发射原理提出了一种气幕的新型形成方式，即通过在身管内壁开设沟槽来引导部分弹后火药燃气向弹前流动形成气幕，进行实时排水。为此建立了充液圆管内多股燃气射流排水过程的三维非稳态两相流模型，并在喷射压力10MPa恒压下进行了数值模拟。结果表明：燃气射流进入充液圆管后产生周向和径向扩展，在周向率先汇聚后开始径向汇聚，最终在管内形成柱状气幕。在射流扩展过程中，Taylor空腔内重复着在弹头斜面产生涡旋、随后涡旋尺度增大并向下游移动、产生新涡旋的过程。随着沟槽宽高比由0.71增大到1.60时，弹头表面静压增大了14.02%，射流轴向扩展速度和气幕排水速率呈非单调变化，并在宽高比1.00时达到最大。而在相同条件下增大喷射面积，虽然射流轴向扩展速度和气幕排水速率提高，但消耗的燃气增多，弹头表面静压也增大，不利于弹丸速度提高。

Abstract:

To improve the launching velocity of the underwater gun projectile， a new formation method of the gas curtain is proposed by using the principle of gas-curtain launching， that is， to guide a part of the gunpowder gas behind the projectile towards the warhead. The gas which flows through several grooves setting up on the inner wall of the body tube forms a gas curtain to conduct real-time drainage. A three-dimensional unsteady two-phase flow mathematical model of multiple gas jets drainage in a liquid-filled tube is established. The numerical study is carried out under the injection pressure of 10MPa. The results show that the gas jets expand in circumferential and radial directions after entering the liquid-filled tube. Jets converge first in the circumferential direction， then in the radial direction， and finally form a cylindrical gas curtain in the tube. During the jets expansion， the following process is repeated in the Taylor cavity： vortex is generated on the warhead， then the vortex scale increases and moves downstream， and a new vortex is generated. When the aspect ratio of the rectangular groove increases from 0.71 to 1.60， the static pressure on the warhead increases by 14.02%， the axial expansion speed and the drainage speed of the jets change non monotonically， and reach the maximum when the aspect ratio is 1.00. Under the same conditions， increasing the injection area， although the axial expansion speed and the drainage speed of the gas curtain increase， the gas consumed increases and the static pressure on the warhead increases， which is not conducive to increasing the projectile velocity.