柴油机燃烧室凸台形状对雾化燃烧性能的模拟

Simulation of Atomization and Combustion Performance ofDiesel Engine Combustion chamber Boss Shape

柴油机燃烧室凸台形状直接影响缸内燃油雾化与燃烧。利用CONVERGE构建并验证柴油雾化和缸内燃烧过程模型,模拟研究凸台形状对柴油机燃烧过程的影响。结果表明:适当增大凸台夹角(126°)可加强燃烧室中心区域的气流运动,增大混合气的扩散面积,加快主喷后期的燃烧放热速度,使得缸内平均指示压力提升2.8%,最大压力升高率降低6.4%。在转速分别为1200rpm、2200rpm、3200rpm下,较大凸台夹角(126°)的燃烧室内混合气燃烧放热更快,对转速适应性更强,放热重心更靠近上止点。

The convex shape of combustion chamber has an important effect on the fuel atomization,and combustion.Using CONVERGE to construct and validate a model of diesel atomization and diesel engine combustion process,and simulates the effects of convex shape.The result show that,moderately increase chamber convex included angle(126°)can enhance airflow movement in the central area of combustion chamber,increase the diffusion area of the mixture,and accelerate the combustion heat release rate in the later stage of the main injection,which can increase the average indicated pressure in the cylinder by 2.8%and reduce the maximum pressure increase rate by 6.4%.At 1200rpm,220 rpm and 3200rpm,larger chamber convex(126°)has a faster mixture heat release,which makes combustion has stronger adaptability to speed,and the heat release center is closer to the top dead center.