船舶发电柴油机冷却腔内沸腾两相流数值模型研究

Numerical Simulation Research of Subcooled Boiling Water in a Marine Generating Diesel Engine Cooling Channel

现代船舶发电柴油机冷却系统设计趋势朝着小型化、整凑型发展,沸腾传热因高效换热能力而备受关注。本文以CFX欧拉双流体模型为基础,通过CCL语句添加用户自定义程序实现对低压系统时矩形通道内过冷流动沸腾的数值模拟。采用Kurul和Anglart修正的过冷度线性关系描述气泡直径;通过改进封闭方程以及经验式,进而改善模型计算收敛性和精度,对不同流动参数下矩形通道内过冷沸腾两相流进行实验与计算对比。计算结果表明随着壁面热流的增加气相体积分数增加;通道质量流量增加气相体积分数下降。该数值模型的建立可为真实船舶发电柴油机冷却水腔沸腾两相流分析奠定基础。

Modern cooling system design of marine generating diesel engine is developed towards small and compact structure, much attention on boiling heat transfer is attracted due to its efficient heat transfer capability. In this paper, a numerical simulation of subcooled boiling in rectangular channel under low pressure conditions is performed on CFX with user defined program. The bubble diameter uses Kurul and Anglart modified correlation and the bubble departure diameter uses Tolubimsky modified correlation with Unal bubble departure diameter used as refer diameter. In addition to, the impact of mass flow and heat flux on void fraction is discussed. Results show that with increasing heating surface heat flux, the void fraction increases, and the mass flow increases, void fraction decreases. The new model can lay a foundation formultiphase simulation in practical engine cooling system.