气射流协助圆盘头部航行体入水空泡特性实验研究

Experimental Investigation on Cavity Characteristics during Water Entry of Disc-Headed Vehicle Assisted by Gas Jet Flow

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的破坏、空泡溃灭与复杂非定常多相流动下的弹道失稳等问题,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和通气量对空泡直径、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。

The trans-medium vehicle is expected to quickly and stably break the free liquid surface.In addition,there are some problems in the trans-medium process,such as the damage to structures and instruments caused by the high impact load,cavity collapse,and ballistic trajectory instability caused by complex unsteady multiphase flow.To address these issues,a forward jet flow was provided at the head of the vehicle to make the vehicle quickly and stably break the free liquid surface.The jet flow penetrated and changed the flow field structure of the free liquid surface to reduce the high impact load.To investigate the multiphase flow characteristics of the cavity during water entry of the disc-headed vehicle assisted by gas jet,the water entry experiment of the disc-headed vehicle assisted by forward jet flow was carried out.The cavity morphology formed during water entry was analyzed,as well as the formation and evolution process of the broken cavity in the case of a gas jet flow impinging on the liquid surface.The effects of different ventilation nozzle diameters and ventilation flow rates on the cavity diameter and jet flow length were discussed.The experimental results indicate that the formation process of the broken cavity includes four stages,namely liquid surface depression,liquid surface oscillation,liquid flow,and cavity formation.The diameter and depth of the broken cavity decrease with the increase in ventilation nozzle diameter and increase with the increase in ventilation flow rate.