Experimental Study on Influence of Ventilation on Trajectory Characteristics of Free Motion of Supercavitating Vehicle

通气对超空泡航行体自由运动的弹道特性影响试验研究

School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

Received: 28 June 2018

Abstract

In order to study the trajectory characteristics of supercavitating vehicle in free motion, a series of experiments were carried out on an unpowered vehicle under ventilation and non-ventilation conditions respectively. High-pressure gas was utilized to launch the vehicle. The flow pattern in free motion was captured by using a high-speed video camera, the variations in the motion parameters and the cavity pressure were simultaneously recorded by using the internal measuring system. The measured data under ventilation and non-ventilation conditions were analyzed in detail, giving the effect of the ventilation on the motion of the vehicle. The experimental results show that the cavitation number fluctuates around a certain value under the influence of both velocity of the vehicle and the ventilation flow rate, keeping the vehicle to stably move in the supercavitating state. Under non-ventilation condition, the vehicle moves stably at the state of supercavitating and double-cavity closed on at the cylindrical section of the vehicle. But the motion turns into instable when the cavity is closed at the shoulder of the vehicle. Therefore, to reduce the cavitation number by ventilation is beneficial to maintaining the stability of the vehicle.

摘要

为了探究超空泡航行体自由运动过程的弹道特性，开展了无动力航行体在通气和不通气情况下的试验。发射装置使用高压气体将航行体发射出管。利用高速摄像机记录自由航行的空泡形态，同时由内测系统记录运动参数和空泡内压力变化。详细分析了通气和不通气下的试验结果，阐述了通气对航行体运动的影响。试验结果表明：通气情况下，在航行速度和通气率共同影响下，空化数保持在某值附近波动变化，航行体以超空泡状态稳定航行；不通气时，航行体依次以超空泡和闭合于圆柱段的双空泡状态稳定航行，当空泡闭合于航行体肩部时运动失稳。因此，采取通气方式降低空化数有助于维持航行体运动的稳定性。