Experimental Investigation on Cavity Flow Characteristics of Water Entry of Disc Head Vehicle With A Gas Jet Cavitator
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摘要: 针对跨介质航行体快速稳定穿越自由液面的需求, 以及目前跨介质过程中存在过大冲击载荷对结构和仪器破坏, 空泡溃灭与复杂非定常多相流动下弹道失稳等问题。探索采用在航行体头部提供向前射流协助其快速稳定穿越自由液面, 射流穿透并改变自由液面的流场结构, 以达到降低过大载荷的目的。为研究气射流协助圆盘头部航行体入水空泡多相流动特性, 开展了向前喷气协助圆盘头部航行体入水实验。分析了入水过程中所形成的空泡形态, 以及气射流冲击液面过程中开口空泡的形成及演化过程, 探讨了不同通气口径、通气量对空泡直径、射流长度等的影响。实验结果表明: 开口空泡形成过程包括液面凹陷、液面振荡、形成流动和空泡形成4个阶段, 开口空泡直径和深度随通气口径增大而减小, 随通气量增大而增大。Abstract: The vehicle quickly and stably penetrating the free surface is the main development trend of trans-media technology. However, some major problems referring to the damage of structures and instruments caused by the high impact load, and ballistic instability caused by nonlinear hydrodynamic induced by the complex unsteady multiphase flow and cavitation collapse are not completely solved using the current method. To achieve quick and stable penetrating of the free surface with minimal structural and ballistic impact on vehicle operation, the concept of the Jet Penetrating Free Surface (JPFS) is put forward in this research. Specifically, a gas jet located in front of the vehicle is used to penetrate the free surface to reduce high-impact load and eliminate the asymmetric load, in which the flow field structure of the free surface is changed by a gas jet. To investigate the multi-phase flow characteristics of disc head vehicle water entry with a gas jet cavitator, the vehicle water entry experiment was carried out. The cavity flow regime form in the process of water entry and the formation and evolution process of the cavity flow during a gas jet impinging on the liquid surface are analyzed. The effects of different ventilation nozzle diameters and ventilation rates on the cavity diameter and jet length are discussed. The experimental results indicate that the cavity formation process includes four stages, i.e., surface depression, surface oscillation, liquid flow, and cavity formation. The diameter and depth of the cavity increase with the decrease of ventilation diameter and the increase of ventilation rate. Three kinds of cavity flow patterns observed in the experiment are defined, which are on cavity, inside cavity, and closure cavity.
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Key words:
- vehicle water entry /
- gas jet /
- cavity classification /
- cavity geometry
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图 5 向前喷气协助圆盘航行体垂直入水过程空泡形成及演化过程(
$ {D}_{n}=3\;\mathrm{m}\mathrm{m},\;{C}_{Qs}=0.17, $ $ {F}_{r}=32.7 $ )Figure 5. The formation and evolution process of cavity during the forward jet assisted the disc vehicle vertical water-entry process(
$ {D}_{n}=3\;\mathrm{m}\mathrm{m},\;{C}_{Qs}=0.17, $ $ {F}_{r}=32.7) $ -
[1] Worthington A M. Impact with a liquid surface studied by the aid of instantaneous photography[J]. Philosophical Transactions of the Royal Society of London, 1900, 194(252-261): 175-199. [2] Von Kármán T. The impact on seaplane floats during landing[J]. National Advisory Committee for Aeronautics, 1929, 321(1929): 309-313. [3] Chuang S. Experiments on flat-bottom slamming[J]. Journal of Ship Research, 1966, 10(1): 10-17. doi: 10.5957/jsr.1966.10.1.10 [4] Chuang S. Experiments on slamming of wedge-shaped bodies[J]. Journal of Ship Research, 1967, 11(3): 190-198. doi: 10.5957/jsr.1967.11.3.190 [5] Okada S, Sumi Y. On the water impact and elastic response of a flat plate at small impact angles[J]. Journal of Marine Science and Technology, 2000, 5(1): 31-39. doi: 10.1007/s007730070019 [6] Huera-Huarte F J, Jeon D, Gharib M. Experimental investigation of water slamming loads on panels[J]. Ocean Engineering, 2011, 38(11-12): 1347-1355. doi: 10.1016/j.oceaneng.2011.06.004 [7] Ermanyuk E V, Ohkusu M. Impact of a disk on shallow water[J]. Journal of Fluids and Structures, 2005, 20(3): 345-357. doi: 10.1016/j.jfluidstructs.2004.10.002 [8] Jiang Y, Shao S, Hong J. Experimental investigation of ventilated supercavitation with gas jet cavitator[J]. Physics of fluids, 2018, 30(1): 012103. doi: 10.1063/1.5005549 [9] Jiang Y, Zou Z, Yang L, et al. Reduction of water entry impact force by a gas jet[J]. Physical Review Fluids, 2023, 8(6): 64005. doi: 10.1103/PhysRevFluids.8.064005 [10] Li Y, Jiang Y, Shen L, et al. Experimental investigation on submerged water jet wrapped in an annular gas jet[J]. Physics of Fluids, 2023, 35(1): 012121. doi: 10.1063/5.0135351 [11] 杨茂, 王涵瑞, 邹志辉, 等. 通气协助航行体出水流动实验研究[J]. 兵器装备工程学报, 2022, 43(12): 29-33, 144. doi: 10.11809/bqzbgcxb2022.12.005Yang Mao, Wang Hanrui, Zou Zhihui, et al. Experimental investigation on ventilated cavity flow characteristics of the vehicle water exit[J]. Journal of Ordnance Equipment Engineering, 2022, 43(12): 29-33, 144. doi: 10.11809/bqzbgcxb2022.12.005 [12] 邹志辉, 李佳, 杨茂, 等. 喷气协助航行体入水空泡流动特性实验研究[J]. 弹道学报, 2022, 34(1): 1-8, 97. doi: 10.12115/j.issn.1004-499X(2022)01-001Zou Zhihui, Li Jia, Yang Mao, et al. Experimental investigation on cavity flow characteristics of water entry of vehicle with gas jet cavitator[J]. Journal of Ballistics, 2022, 34(1): 1-8, 97. doi: 10.12115/j.issn.1004-499X(2022)01-001 [13] Banks R B, Chandrasekhara D V. Experimental investigation of the penetration of a high-velocity gas jet through a liquid surface[J]. Journal of Fluid Mechanics, 1963, 15(1): 13-34. doi: 10.1017/S0022112063000021 [14] Hwang H Y, Irons G A. A water model study of impinging gas jets on liquid surfaces[J]. Metallurgical and Materials Transactions B, 2012, 43(2): 302-315. doi: 10.1007/s11663-011-9613-3 [15] Rabbi R, Speirs N, Kiyama A, et al. Impact force reduction by consecutive water entry of spheres[J]. Journal of Fluid Mechanics, 2021, 915: A55. doi: 10.1017/jfm.2020.1165 -