汽油在超临界环境下的喷雾特性

利用超临界平台和定容燃烧弹系统,将低亚临界态(low sub-critical state,LS-CS)、亚临界态(sub-critical state,S-CS)和超临界态(super-critical state,Sup-CS)等不同状态的汽油,喷入到超临界环境(super-critical environment,Sup-CE)。依托纹影系统,得到汽油在超临界环境中的喷雾特性,并与常温常压环境(ambient temperature and atmospheric pressure environment,AT&APE)汽油喷雾特性进行详细对比。研究结果表明:在超临界环境下,同一喷射时刻,随着喷油温度的升高,单孔喷油器的喷雾贯穿距先增加,后平稳下降,但在超临界态一直攀升;喷雾面积先上升,在亚临界态初段达到峰值后波动下降。5孔喷油器的喷雾贯穿距先平稳上升,后急速下降到低于初始值;喷雾面积先增加,在亚临界态缓慢下降,在超临界态初期达到峰值后下降。此外,在喷射条件相同时,超临界环境下和常温常压环境下的喷雾形态发展有明显区别,由于超临界环境下喷雾与环境的相互作用,塌缩现象及气泡微爆现象主导喷雾的发展,喷雾贯穿距和喷雾面积随时间的变化量远小于常温常压环境下的喷雾贯穿距和喷雾面积。

Spray Characteristics of Gasoline in Super Critical Environment

Using a super-critical platform and a constant volume combustion bomb system, gasoline with different critical states, including low subcritical, subcritical and supercritical state gasoline was injected respectively into a supercritical environment, and then the spray characteristics of the gasoline obtained from the schlieren imaging system were compared with those in the normal temperature and pressure environment. Results show that in the supercritical environment and at the same injection timing, as the injection temperature rises, the spray penetration of the single-hole injector increases first and then decreases steadily, but it is always increasing for supercritical state gasoline. The spray area continues to expand, but for the subcritical state gasoline, it fluctuates and falls after reaching its peak. And as the injection temperature rises, the spray penetration of the five-hole injector first rises steadily, and then drops rapidly below the initial value. The spray area increases first and then decreases slowly for subcritical state gasoline or falls after reaching its peak for supercritical state gasoline. In addition, under the same spraying conditions, the development of spray pattern in the supercritical environment is significantly different from that in the normal temperature and pressure environment. Due to the interaction of the spray and environment in the supercritical environment, the collapsing phenomenon and the micro-explosion of the bubble will dominate the development of the spray. The variation of the spray penetration and spray area with time will be much smaller in the normal temperature and pressure environment.