车用天然气发动机增压匹配及性能参数优化

Turbocharging Matching and Performance Parameter Optimization of Vehicle Natural Gas Engine

运用GEM3D工具离散化的方法建立了某1.5L自然吸气车用CNG(压缩天然气)发动机GT-Power仿真模型,并用试验数据对模型进行校核,模型最大误差为3.64%。在此基础上进行了CNG发动机增压器匹配分析,用DoE(design of experiment)工具对增压发动机的点火提前角进行了优化,然后优化了不同压缩比和不同过量空气系数下的点火提前角,对压缩比和过量空气系数进行了计算分析。结果表明:仿真模型具有较高精度,方案2为4种涡轮增压器方案中最佳方案,并对该方案进行了台架试验,仿真结果与试验结果误差在4%以内;通过优化点火提前角,扭矩最大提高了9.3%;在各最优点火提前角下,压缩比为12时最优,过量空气系数为1.1时具有最佳经济性。

A 1. 5 L naturally aspirated compressed natural gas （CNG） engine model was established with GT-Power through GEM3D discretization method. The model was verified against experimental data and the maximum error was 3. 64%. Then the matching and analysis of turbocharger for CNG engine were conducted and the ignition advance angle was optimized with DoE tool. The compression ratio and excess air coefficient were calculated and analyzed and their corresponding ignition advance an-gles were also further optimized. The results show that the simulation model has a high precision and the second scheme is the best among the four kinds of turbochargers. For the determined best scheme, the bench verification is conducted and the error between simulation and experiment is within 4%. The maximum increase of torque is 9. 3% by optimizing the ignition advance angle. For all best ignition advance angles, the optimal compression ratio is 12 and the excess air coefficient for best fuel econo-my is 1. 1.