基于压前管路的某V型天然气发动机燃气混合均匀性优化

杨鹏^1，2，孙放^1，2，侯岩舒^1，2，李德华^1，2，高坤^1，2

1．内燃机可靠性国家重点实验室，山东 潍坊  261061；2．潍柴动力股份有限公司，山东 潍坊  261061

摘要：为解决某V型天然气发动机两侧气缸燃气混合不均匀的问题，采用计算流体动力学软件建立压气机前、后管路模型，分析混合不均匀原因，优化混合器安装角度、压前管路结构，并进行仿真和发动机性能试验验证。仿真结果表明：混合气在流体运动产生的离心作用下向压前弯管内侧聚集，导致两侧气缸混合气不均匀；将混合器安装角度旋转45°，两侧气缸天然气质量分数偏差由压前管路的0.195降为0.129，说明混合均匀性有改善，但幅度不大；将压前管路光滑过渡弯头改为直角弯头，两侧压气机入口处天然气质量分数偏差由优化前的0.195降为-0.005，混合均匀性明显得到改善。改进前、后的发动机性能试验结果表明：优化后，两侧缸内平均爆发压力相对偏差由14.5%降为9.0%。两侧缸内平均爆发压力偏差与天然气质量分数偏差有较好的吻合性，说明优化压前管路结构可明显提高发动机混合均匀性。

关键词：天然气；混合器；混合均匀性；计算流体动力学；压前管路

Optimization of gas mixing uniformity for a V-type natural gas engine based on the pipeline in front of the compressor

YANG Peng^1,2，SUN Fang^1,2，HOU Yanshu^1,2，LI Dehua^1,2，GAO Kun^1,2

1.State Key Laboratory of Engine Reliability, Weifang 261061, China;

2.Weichai Power Co., Ltd., Weifang 261061, China

Abstract：In order to solve the problem of uneven gas mixing between the two cylinders of a certain V-type natural gas engine, computational fluid dynamics software is used to establish models of the front and rear pipelines of the compressor, analyze the reasons for uneven mixing, optimize the installation angle of the mixer and the structure of the intake pipeline, and conduct simulation and engine performance testing verification. The simulation results show that under the centrifugal effect generated by fluid motion, the mixture accumulates towards the inner side of the pressure front bend, resulting in uneven mixture between the two cylinders. Rotating the mixer by 45 °, and the deviation of natural gas mass fraction on both sides of the cylinder decreases from 0.195 to 0.129, indicating an improvement in mixing uniformity, but it is quite limited. The smooth transition elbow of the intake pipeline is changed to a right angle elbow, and the deviation of the natural gas mass fraction at the inlet of the two compressors on both sides is reduced from 0.195 to -0.005. The mixing uniformity is significantly improved. The performance test results of the engine before and after improvement show that after optimization, the average explosion pressure deviation in both cylinders has been reduced from 14.5% to 9.0%. There is a good agreement between the deviation of average explosion pressure on both sides of the cylinder and the deviation of natural gas mass fraction, indicating that optimizing the intake pipeline structure can significantly improve the mixing uniformity of the engine.

Keywords: gas; mixer; mixing uniformity; computational fluid dynamics; the pipeline in front of the compressor