柴油机喷雾燃烧相似性理论基础研究

Fundamental Theory of Diesel Spray and Combustion Similarity

基于相似理论,从基本控制方程出发,推导并分析了柴油机喷雾燃烧过程中重要的无量纲数,阐明了不同尺寸柴油机扩散燃烧过程、预混燃烧过程及喷雾过程存在相似性的理论依据。在满足几何相似的前提下,阐明了试验设计时实现不同尺寸柴油机燃烧相似的转速、喷油压力、喷油持续期等运行参数需满足的条件。当柴油机预混合燃烧过程不能被忽略时,应维持大、小柴油机转速相同以实现燃烧相似。

Based on the similarity theory,some of important dimensionless numbers in diesel spray and combustion were deduced and discussed by basic conservation equations.The existence of similarity in different diesel engines was proved theoretically in diffusion and premixed combustion processes,and also in spray mixture formation process.On the premise of geometric similarity,scaling rules for some parameters including engine speed,injection pressure and injection duration were established to realize the similarity between large-bore and small-bore diesel engines.In the engine operations where premixed combustion is remarkable,the scaling rule that keeps the engine speed unchanged is more preferable.