摇摆对自然循环系统流量及载热能力影响分析

Analysis of Rolling Effects on the Flow and Heat Transport Capacity of a Natural Circulation System

自然循环载热系统由密度差引起的重位压差驱动,驱动压头小且受冷热源位置和冷热流体温度影响,因此摇摆等海洋工况会对自然循环载热系统的载热能力产生较大影响。在固连坐标系内,采用理论分析和数值计算方法对自然循环载热系统的流量及载热能力进行了研究。理论分析给出了摇摆产生的各项附加力对自然循环载热系统的流量及载热能力的影响机理,并得到了摇摆条件下自然循环系统流量的常微分控制方程。数值计算方法中针对动量方程添加了由于摇摆产生的各种附加作用力项。数值计算得到的系统流量波动结果与理论分析结果吻合得很好,并且数值计算还给出了由于摇摆使系统载热能力下降的幅度。

Natural circulation system is driven by gravity pressure difference caused by density difference.The value of the driving pressure head is small,which is affected by the positions of the cold and heat sources and the temperatures of the fluid.Therefore,ocean conditions,such as rolling,will largely influence the heat transport capacity of natural circulation systems.The flow rate and heat transport capacity were investigated using theoretical and numerical methods in the fixed coordinates.Theoretical analysis shows the mechanisms of how the rolling induced additional forces influence the flow rate and heat transport capacity of a natural circulation system.The governing ordinary differential equation for the mass flow rate of a natural circulation system under rolling condition is derived.In the numerical methods,additional force terms caused by rolling are added to the momentum equation.Numerical results of the flow rate fluctuation agree well with the theoretical results.The numerical results also show the decrement of the heat transport capacity of the system under rolling condition.