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本文叙述并讨论利用高速闪光的单张摄影方法来研究柴油机中的喷雾。由于文中提供的实验装置和方法可以取得在同一个精确角位下多次重复喷射的雾注照片,故可采用统计方法对喷注以及与之相关的燃油喷射系统的稳定性进行观察和分析。通过对不同角位摄取大量照片可以得到具有统计平均意义的喷雾贯穿度一时间特性。对喷雾贯穿特性的研究表明,在喷油时间t≤1毫秒(ms)时,贯穿度(s)∞t~a,其中a值为1.1—1.2,而仅在t>1ms以后,方存在着以前有关文献中确认的S∞t~0.5关系。通过理论分析,说明在使用相同的喷咀结构时,各时期的平均喷油速率可以与喷雾贯穿特性直接联系起来,即在着火延迟期内,值决定了t=1ms时的初始贯穿度S_1,而在喷射后期,与贯穿度常数S~2/t的大小成正比例。为查明贯穿特性对柴油机性能的影响,文中通过若干发动机试验结果,进行了初步分析。
This article describes and discusses the use of high-speed flash single-shot photography method to study the diesel engine spray. Since the experimental setup and method provided in this paper can obtain the misty shots with multiple repetitions of injection at the same precise angle, the injection method and the stability of the fuel injection system can be observed and analyzed statistically. By taking a large number of photos at different angular positions, it is possible to obtain a time-average characteristic of spray penetration through a statistically significant mean. The study on the penetration characteristics of the spray shows that the penetration (s) ∞ t ~ a, the value of a is 1.1-1.2 at the time of t ≤ 1 millisecond (ms) and exists only after t> 1ms Previously confirmed in the literature S∞t ~ 0.5 relationship. The theoretical analysis shows that when using the same nozzle structure, the average injection rate of each period can be directly related to the spray penetration characteristics, that is, during the ignition delay period, the value determines the initial penetration S_1 at t = 1ms, In the latter part of the jet, it is proportional to the penetration constant S ~ 2 / t. In order to find out the influence of penetration characteristic on the performance of diesel engine, a preliminary analysis is carried out through several engine test results.