风冷汽油机热载荷分析及喇叭型导流罩的影响研究  

Analysis of Thermal Load of Air-Cooled Gasoline Engine and Effect of Engine Flared Fairing

作　　者：张俊红[1,2] 王西博 林杰威 张立鹏[3] 郑越洋[3] 阎岩 戴胡伟 ZHANG Junhong;WANG Xibo;LIN Jiewei;ZHANG Lipeng;ZHENG Yueyang;YAN Yan;DAI Huwei(State Key Laboratory of Engines,Tianjin University,Tianjin 300354,China;Mechanical Engineering Department of Tianjin Ren’Ai College,Tianjin 301636,China;Tianjin Internal Combustion Engine Research Institute,Tianjin 300072,China)

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300354 [2]天津仁爱学院,天津301636 [3]天津内燃机研究所,天津300072

出　　处：《西安交通大学学报》2023年第4期1-10,共10页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(51875397);中国博士后科学基金资助项目(2021M702430)。

摘　　要：为了深入分析热载荷对风冷发动机运行稳定性的影响,通过CONVERGE仿真软件对某四冲程风冷式汽油发动机缸内燃烧过程进行数值模拟计算,获得了完整的缸内燃气侧热边界条件。基于FLUENT仿真软件,建立发动机热流固耦合稳态传热仿真模型,获得了燃气侧不均匀热载荷与机体外复杂空气流动共同作用下的发动机热载荷分布,并通过台架实验验证了稳态传热仿真的准确性。设计喇叭型结构导流罩,分析了导流罩收缩比对导流罩性能的影响,改善发动机的冷却效果。结果表明:发动机稳态传热仿真与台架测试最大误差为3.12%,仿真模型具有较高的准确性;发动机机体最高温度为655 K,出现在排气道端口处位置;随着导流罩收缩比的减小,发动机冷却散热性能增强,收缩比λ为1.94时,冷却强化效果最好,机体最高温度降低8.8 K。研究对风冷汽油机的冷却系统设计及优化具有一定的指导意义。To further analyze the influence of thermal load on the operational stability of air-cooled engine,a numerical simulation of the gas-side thermal load distribution characteristics of a four-stroke air-cooled gasoline engine were conducted using CONVERGE simulation software.The steady-state heat transfer fluid-solid interaction numerical model of the engine was modeled using FLUENT to obtain the thermal distribution under the combined effect of uneven spatial distribution of gas-side thermal load and complex air flow on the outside of the engine,of which the accuracy of the numerical model was verified by bench tests.A flared fairing is proposed,and the effect of deflector shrinkage ratio(λ)on the engine thermal load was analyzed to improve engine cooling effect.The results showed that the maximum difference of the numerical model results and experimental results was 3.12%,which proved the simulation model had high accuracy.The maximum temperature of the engine was 655 K at the exhaust side,and the cooling performance of the engine was enhanced by decreasing the shrinkage ratio of the fairing.The cooling enhancement was the best when at λ=1.94,and the maximum temperature was reduced by 8.8 K.The study has guiding significance for the design and optimization of cooling systems for air-cooled gasoline engines.

关 键 词：风冷汽油机 耦合传热 热载荷 导流罩 

分 类 号：TK421.4[动力工程及工程热物理—动力机械及工程]