发电机组流场特性数值模拟及其散热优化研究

发电机组高性能和轻量化的设计需求对其冷却系统提出了更高的要求。发电机组工作时机舱温度上升快，其散热性能不好直接影响其高效正常运行。文章以发电机组为研究对象，采用CFD软件STAR-CCM+ 11.06对某发电机组整机流场特性进行数值模拟分析，并采用单一变量控制方法对风量提升进行研究。结果表明:该发电机组原结构风扇进风风量仅为40 g/s，发动机热风回流导致电机进风量增大，不利于电机的冷却；通过调整进风结构、减小出风阻力和添加隔热挡板均可以提升风量，其中添加隔热挡板后发电机组风量提升明显且能有效消除热风回流现象。依据单因素分析结果提出了调整左右进风口布置、加大消声器护罩出口、添加发动机隔热挡板的组合方案，优化后的发电机组风扇进风量提升至75. 79 g/s，总风量提升明显；热风回流被隔热挡板充分隔断，电机热风循环减少；油箱、化油器、点火器的表面速度明显提升。发电机组总进风量增加，机组内空气流速快，有利于发电机组的冷却，可保障其高效正常地运行。发电机组流场特性数值模拟及其散热优化研究结果可为后续发电机组的设计及改进提供参考。

Numerical Simulation on Flow Field Characteristics and Cooling Performance Improvement of a Generator Unit

The high performance and lightweight design requirements of generator sets put higher requirements for their cooling system. When the generator unit works, the engine room temperature rises rapidly, and its poor heat dissipation performance directly affects its efficient and normal operation. In this work, a generator unit is taken as the research object, and CFD software STAR-CCM + 11.06 is used to simulate and analyze its flow field characteristics, and the single variable control method is used for finding a way for increasing the total inlet air quantity. Results show that the fan inlet air quantity of the original generator unit is only 40 g/s. The hot air re-circulation of the engine leads to the increase of the air inlet quantity of the motor, which is not conducive to motor cooling. The air quantity can be increased by adjusting the air inlet structure, reducing the air outlet resistance and adding thermal insulation baffle. After adding thermal insulation baffle, the air quantity of generator unit can be increased significantly and the phenomenon of hot air re-circulation can be effectively eliminated. According to the results of single factor analysis, the combination scheme of adjusting the layout of left and right air inlets, increasing the size of muffler cover outlet area and adding baffle to the engine is put forward. After optimization, the total fan inlet air quantity of generator unit is increased to 75.79 g/s. The total air quantity is increased significantly. The hot air re-circulation is fully eliminated by the heat insulation baffle, and the hot air circulation of motor is reduced, which is beneficial to motor cooling. The cell relative velocity magnitude of oil tank, carburetor and igniter is significantly improved. The total air inlet quantity of generator unit increases significantly and the airflow velocity in generator unit rises, which is beneficial to the cooling of generator unit and can ensure its efficient and normal operation. The results of flow field characteristics and cooling performance improvement study of generator unit can provide theoretical guidance for the design and improvement of generator units.