基于水下炮射通气式超空泡射弹的气液相互作用机理研究

Taking transonic and supersonic projectile launched by submerged gun as the engineering background, this project proposes a new way of underwater launch that using gunpowder gas pushes aside water column in the front end of high-speed projectile moving in the gun tube in real time to realize steady and controllable launch of submerged gun. Based on this new idea, the mechanism study on the interaction of multiple combustion-gas jets and water column in the front end of motion body in circular tube is further carried out. The special visible experimental devices on the interaction of three combustion gas generators and water column in the circular tube are designed. The structures and interference characteristics of Taylor cavities formed by injecting the four to eight slit-like combustion-gas jets with high speed in inner wall of circular tube and four conical combustion-gas jets in the front end of projectile (quiescent state) into the water in the circular tube are observed respectively. The drainage mechanism under the combined effect of multiple combustion-gas jets is mainly explored to reveal the new mechanism of high-speed launch below the water. Moreover, the high-speed firing test below the water for ventilated projectile is carried out to observe characterization of the supercavitation when the projectile flies away the muzzle. Based on the experiments, the model of gas-liquid interaction is established and the numerical simulation is conducted from the theory of unsteady-state heat transfer, turbulent flow and multiphase fluid dynamics. This study has positive significance on promoting the development of hydrokinetics theory and experimental technique, and lays theoretical foundations for developing the technique of the high-performance underwater gun.

本项目针对浸没在水下火炮发射跨、超音速射弹的工程背景，提出一种水下发射新方式，即：利用火药燃气实时排开炮管中高速运动弹丸前端的水柱，实现水下火炮的稳定可控发射。基于此新构思，深入开展多股燃气射流与圆管中运动体前端的水柱相互作用机理研究。设计三种燃气射流发生器与圆管中水柱相互作用的特殊可视化试验装置，利用高速录像、瞬态压力测量系统等设备，分别观测圆管内壁4-8股狭缝高速燃气射流、运动体前部4股锥形燃气射流，在圆管水中形成泰勒空腔的结构与干涉特性，重点探索多股射流协同排水机制，揭示水下高速发射的新机理；开展通气式射弹在水下高速发射试验研究，重点观测射弹出膛口时超空泡的形态特征。在实验基础上，从非稳态传热、湍流及多相流体动力学等理论出发，建立气液相互作用模型，并进行数值模拟。该项研究对促进流体动力学理论与实验技术的发展有重要意义，同时也可为我国开发高性能水下火炮技术奠定理论基础。

本项目以全淹没式水下枪炮发射为背景，提出一种水下枪炮高效低阻发射的新方法，并开展了相关发射原理的多相流体动力学特性的基础性研究工作，主要研究内容及成果如下：（1）开展了多股贴壁狭缝形燃气射流与圆管中水柱相互作用特性的实验研究，通过设计专门的模拟实验装置，获得了Taylor空腔演化、气液湍流掺混和多股射流相互干涉等特征规律。建立了气液两相三维非稳态数学物理模型，并进行了数值模拟，获得了射流场中两相组分、压力、温度、速度以及流场涡旋结构演化特性的时空分布规律，揭示了Taylor空腔内部膨胀波和压缩波对于流场特征参数分布的影响，以及多股射流间干涉作用对于射流协同排水减阻的机理。（2）开展了锥形分布的多股燃气射流在柱形充液室内扩展特性的实验研究，观测它在圆管充液室中形成多股Taylor空腔扩展、撞壁、汇聚等特性。通过数值模拟揭示出喷嘴结构和喷射压力耦合作用条件下，气液两相流场压力、速度等参量的时空分布规律和Taylor空腔、回流区、气流核心区内波系结构的演化特性。（3）开展了多股燃气射流协同排水的模拟发射试验与数值分析，设计模拟发射装置和试验弹，获得了弹丸运动条件下多股燃气射流生成弹前气幕与弹丸低阻运动的耦合匹配关系。通过数值模拟揭示出气幕生成过程中多股射流间相互干涉、汇聚对气液两相流场和弹丸动力学特性的影响规律。（4）开展了水下枪炮发射膛口流场及射弹超空泡形成特性的数值分析，建立了水下发射膛口射流场的理论模型，获得了水下膛口两相流场及波系的演化特征；建立了高速射弹飞离膛口时超空泡形成的非稳态模型，通过数值模拟揭示出800-1300m/s的射弹水中形成超空泡的形态与特征。本项目研究成果为深入研究火药燃气射流协同排水的水下枪炮发射新技术奠定了理论基础。本项目已发表国际期刊SCI收录论文8篇，国内核心期刊EI收录论文10篇，申请并受理国防发明专利3项。培养博士生5名，已毕业3名。