Exploitation of Hypervelocity liquid jet generator by using Neumann effect

高速液体射流已被广泛应用于柴油发动机的燃油喷射过程和水射流切割技术。然而，它们的峰值速度可达1公里/秒。今天，无论是产生高速液体射流的方法，还是对它的理解，在技术上都还没有得到很好的发展。此前，该项目的首席研究员已经开发出一种技术，通过使用单级气枪，将1-2公里/秒的平头高速弹丸撞击液体容器，产生3-4公里/秒的高速射流。然而，这种方法需要一个非常精心设计的不可重复使用型喷嘴，因此它永远不会实用。众所周知，在火力工程中，一枚反向锥形装药一旦引爆，就会沿其轴线产生非常高速的碎片射流，其原理被称为冯·诺伊曼效应。利用冯·诺依曼效应，利用高速平头活塞撞击反锥形水容器，可以产生高速液体射流。本项目旨在对高速液体射流的产生进行数值模拟，并在此基础上构建一个小型的、可以产生高速液体射流的装置，作为冯·诺依曼效应的延伸。结果表明：(1)数值模拟表明，射流速度增益大于活塞速度增益的50%。(2)反向锥型的顶点角约为22度，射流速度在3 ~ 6 km/s之间。(3)研制了口径为15 mm的单级气体太阳，在无烟火药量为0.5 ~ 1.5 g的情况下，驱动初速为0.6 ~ 1.5km/s的弹丸。(4)成功地进行了全息干涉观测，可视化了液体射流的形成和破碎过程。(5)澄清了液滴的飞行和破碎，结果表明，在技术上可以获得超过6 km/s的高速水射流。少

High speed liquid jets have been intensively applied to the process of fuel sprays in diesel engines and also water jet cutting technology. However, their peak speed ranges up to 1 km/s. Today neither the method of generating high speed liquid jets nor its underatanding have not yet been technically well developed. Previously the chief investigator of this project has developed atechnology in which by using a single stage gas gun the impact of a flat headed high speed projectile of 1-2 km/s on a liquid container created high speed jets of 3-4 km/s. However, this method required a very elaborately designed non-reusable type nozzle so that it can never be practical. It is well known that in pyro-engineering a reverse cone shaped charge, once detonated, produced a very high speed debris jet along its axis, whose principle is called the von Neumann effect. High speed liquid jets can be readily produced by following the von Neumann effect when a reverse cone shaped water container was impin … More ged by a high speed flat headed piston. This project aims to simulate numerically the generation high speed liquid jets and based upon the numerical result to construct a compact facility which can generate high speed liquid jets as an extension of the von Neumann effect. Results obtained are summarized as following :(1) Numerical simulation revealed that the gain in jet speeds was over 50 % of piston speeds.(2) The apex angle of reverse cone shapes was approximately 22 degree and the resulting jet speed ranged from 3 to 6 km/s.(3) A single stage gas sun of 15 mm bore was manufactured which drove projectiles with muzzle speed of 0.6 to 1.5km/s for the amount of smokeless powder of 0.5 to 1.5 gr.(4) Holographic interferometric observations have been successfully carried out to visualize the formation and fragmentation of liquid jets.(5) The flight and fragmentation of liquid droplets have been clarified and their results revealed that it is technically possible to obtain a high speed water jet exceeding over 6 km/s. Less