温度分层环境中水面船模气泡尾流电导率特性的实验研究

Experimental research on bubble wake′s conductivity characteristics of surface ship model in temperature stratification flow field

为了研究温度分层和气泡对水面舰船尾流电导率信号影响的规律,在有无气泡两种情况下,分别在恒温水槽和温度分层水槽中检测了水面船模尾流的电导率信号,并分析了水面船模航速对温度分层环境中船模气泡尾流电导率信号的影响。实验结果表明:无论温度分层和气泡是否存在,都不会改变尾流核心区电导率信号随深度增加而降低的特征;与恒温流场相比,温度分层的存在使得尾流宽度变小(例如由恒温流场时的2.2B(船宽)降低为1.5B);在温度分层环境中船模低速航行时的气泡尾流半宽约为高速航行时的二分之一;气泡的存在使得尾流的电导率信号波动变大;当温度分层和气泡同时存在时,在尾流的上层内气泡引起尾流电导率信号降低的作用基本被温度掺混造成的影响抵消,但是气泡的上浮运动会加速尾流上层温度的降低。

In order to study the effects of the bubbles and temperature stratification on the conductivity signal of the wake, the conductivity signals of a surface ship model＇s wake were detected respectively in constant temperature environment and in temperature stratification environment with or without bubbles. And the influence of ship model＇s velocity on the conductivity signal of the bubble wake in the temperature stratification environment was analyzed. The experimental results show that the conductivity signal of the wake core decreases with the increase in the wake depth whether the bubbles and the temperature stratification exist or not. The width of the wake in temperature stratification environment , which is 1.5 times of the width of ship model （ B ） , is narrower than the one in constant temperature environment, which is 2.2B. When the ship model is navigating at low speed the width of wake is almost half of the one when the model is navigating at high speed in temperature stratification environment. The fluctuation of conductivity signal of wake becomes more intensive when bubbles exist. If both bubbles and temperature stratification exist, the effect that the bubbles cause the conductivity signal to be reduced is almost offset by the influence of the mixture of different temperature water on the upper wake, but the temperature of upper wake will be rapidly cut down by the rising motion of bubbles.