不同ω形凹坑燃烧室内湍流特性的计算

Computing on Turbulent Flow Properties in Combustion Chambers With Different ω-Shape-Pits

内燃机缸内流动是及其复杂的三维湍流流动,其流动具有强压缩性、强旋转和各向异性的特点。模拟和分析内燃机的燃烧和排放,需要对缸内湍流运动描述和模拟。把采用了应力张量和应变张量的三阶相关关系的一个非线性涡粘度湍流模型进行修正后应用于内燃机缸内湍流流动计算,用此模型对几种ω形凹坑燃烧室内燃机汽缸内的流动进行计算,特别考查不同结构燃烧室内各处的湍能的变化,给出了燃烧室结构对缸内湍能影响结果,结果表明,凹坑结构对内燃机缸内湍能的分布和平均湍能的大小影响很大,可适当调整燃烧室结构来改变缸内湍流结构。

Gas flow inside internal combustion engine cylinders is a very complicated 3D turbulent flow. The characteristic of turbulent flow in engines is highly compressible, rotational and anisotropic. To simulate and analyze combustion and exhaust accurately, it is necessary to describe and simulate the movement of turbulent flow in cylinder, A nonlinear eddy- viscosity turbulent flow model, which adopted third - order correlation of stress tensor and strain tensor, was modified and applied to flow computing of turbulent flow of internal combustion engine, The model was used to compute gas flow of several kinds of ω - shape - pit combustion chambers, and emphasizes on observing the change of turbulence energy located in different places of the combustion chambers with different structures, The result that the structure of combustion chambers influences the turbulence energy in the cylinders was given, The result shows that pit structure has a heavy influence on distribution of turbulence energy and average turbulent energy. Through adjusting properly the structure of combustion chambers, turbulent flow structure can be changed,