高压气底吹进气吹除主压载水舱过程分析

Analysis of the blowing process of high pressure air from the bottom into the main ballast tank

采用直接求解流动控制方程的CFD方法对高压气底吹进气吹除主压载水舱过程进行分析。获取吹除过程关键参数,着重分析通海孔面积、气源压力对吹除过程的影响,探索高压吹除过程一般性规律。底吹进气高压气出流方向与通海孔水流方向相反,高压气由通海孔泄漏较少;通海孔面积越大,气源压力越高,吹除用时越短;通海孔面积的增加可以有效减少吹除过程中的高压气消耗,对降低主压载水舱内的压升也有显著作用,通海孔面积增大2倍,3种工况下主压载水舱内的最大压升分别减小0.01 MPa,0.10 MPa和0.15 MPa;吹除过程中高压吹除管路出口气流速度可达1Ma以上,管路出口段的温降也明显大于管路入口段,应将不耐低温的阀门和仪表布置在管路入口段附近。

The blowing process of high pressure air entering from the bottom of the main ballast tank is analyzed by CFD method which directly solves the flow control equation.To explore the general law of high pressure blowing process,the key parameters of blowing process are obtained and the influence of sea opening area and air source pressure on the blowing process is mainly analyzed.The direction of high pressure air outflow is opposite to the direction of water flow through the sea opening in the process of bottom blowing.Therefore,the high pressure air leakage from the sea opening is less.The blow-out time decreases with the increase of sea opening area and air source pressure.The increase of the sea opening area can effectively reduce the consumption of high pressure air and has a significant effect on reducing the pressure rise in the main ballast tank.The maximum pressure rise in the main ballast tank decreases by 0.01 MPa,0.10 MPa and 0.15 MPa respectively when the area of sea opening increases by two times.In the blowing process,the airflow velocity can be accelerated to more than 1 Ma at pipe outlet,and the temperature drop at pipe outlet is also significantly greater than that at pipe inlet,which indicates that low-temperature resistant values and instruments should be placed near the pipe inlet.