柴油机排气道改进对散热量的影响  

A Modification of Diesel Exhaust Ports and Its Influence on Heat Dissipation

作　　者：李超 董朵 李连升 马庆镇 马伟 Li Chao;Dong Duo;Li Liansheng;Ma Qingzhen;Ma Wei(State Key Laboratory of Engine Reliability,Weichai Power Company Limited,Weifang 261061,China)

机构地区：[1]潍柴动力股份有限公司内燃机可靠性国家重点实验室,山东潍坊261061

出　　处：《内燃机学报》2023年第6期547-553,共7页Transactions of Csice

摘　　要：降低缸盖排气道的散热量能提高发动机热效率和排气温度,以某6缸重型柴油机为研究对象,结合流固耦合计算和一维、三维耦合计算,获得了较为准确的一维热力学模型.在此基础上设计不同表面积和直径的排气道方案,采用一维热力学仿真,计算各方案在多工况下的对流换热系数、散热量和涡前排气温度.结果表明:气侧对流换热系数基本不受气道表面积影响,但会随着气道直径的增大而迅速下降,并与直径的平方呈反比.散热量随着气道表面积减小等比例减小,也会随着直径增大而降低,且降低比例稍低于气侧对流换热系数的降低比例.涡前排气温度随着排气道散热量的降低而升高,A4方案的涡前排气温度最高,表面积减小到60%,标定工况点可以提升22.6℃.Reducing heat dissipation from the exhaust ports of cylinder head is helpful to increase the thermal effi-ciency and exhaust temperature of the engine.The influence of exhaust ports design on heat dissipation was studied on a six-cylinder heavy duty diesel engine.A more accurate one-dimensional(1D)thermodynamic model was obtained by combining calibration with fluid-solid coupling calculation and 1D-3D coupling calculation.Multiple schemes of the exhaust ports were designed with different surface areas and diameters.1D thermodynamic simulation was used to calculate the convective heat transfer coefficient,heat dissipation and exhaust temperature before turbine under multiple working conditions for each scheme.The results show that the air-side convective heat trans-fer coefficient is not affected by the port surface area,but decreases rapidly with the increase of the port diameter,and is inversely proportional to the square of the diameter.The heat dissipation decreases proportionally with the decrease of the port surface area and also with the increase of the diameter,and the decreasing ratio is slightly lower than that of the air-side convective heat transfer coefficient.The exhaust temperature before turbine increases with the decrease of heat dissipation from the exhaust ports.A4 scheme gives the highest exhaust temperature with an increase of 22.6℃at the rated power point since its surface area is reduced to 60%.

关 键 词：柴油机 排气道 散热量 对流换热系数 涡前排气温度 

分 类 号：TK422[动力工程及工程热物理—动力机械及工程]