滑动轴承油水冷却器的换热与流阻特性

Heat Transfer and Flow Resistance Characteristics of Oil-Water Cooler for Sliding Bearings

滑动轴承运行过程中油膜剪切和搅油产生的功耗约80%会转换成热量,导致油箱内润滑油温度升高,为将润滑油温度控制在设计值内,通常在油箱内安装油水冷却器带走热量,冷却器换热性能直接影响滑动轴承的运行温度和主机的正常工作。油水冷却器的散热能力主要由换热系数和流阻特性决定,对不同油流量条件下的油水冷却器进行试验测试,研究其换热和流阻特性,结果表明:在控制进油、进水温度及进水流量的前提下,油流速在一定范围内增加时,换热系数先增加后趋于稳定,压力损失增大,换热因子和阻力系数减小,冷却器可在一定油流速范围内获得最佳的换热和流阻特性;试验获得了对数坐标系下努赛尔数、欧拉数与雷诺数的拟合曲线,理论计算与试验拟合结果具有良好一致性,并在此基础上获得了油流速与换热系数及流阻的经验公式。

About 80%of power consumption generated by oil film shear and oil stirring during operation of sliding bearings will be converted into heat,resulting in temperature rise of lubricating oil in oil tank.In order to control the temperature of lubricating oil within design value,an oil-water cooler is usually installed in oil tank to take away heat.The heat transfer performance of the cooler directly affects the operating temperature of sliding bearings and normal operation of main engine.The heat dissipation capacity of the cooler is mainly determined by heat transfer coefficient and flow resistance characteristics.The tests are conducted on the cooler under different oil flow rates to study heat transfer and flow resistance characteristics.The results show that under the premise of controlling inlet oil,inlet water temperature and inlet water flow rate,when oil flow rate increases within a certain range,the heat transfer coefficient increases first and then tends to be stable,the pressure loss increases,and the heat transfer factor and resistance coefficient decrease,the cooler can obtain optimal heat transfer and flow resistance characteristics within a certain range of oil flow rates;the fitting curves of Nusselt number,Euler number and Reynolds number in logarithmic coordinate system are obtained through tests,the theoretical calculation and test fitting results have good consistency.On this basis,the empirical formulas for oil flow rate,heat transfer coefficient and flow resistance are obtained.