超临界二甲醚喷雾特性的试验研究

为研究超临界二甲醚的喷雾特性,在定容容器内模拟涡轮增压发动机气缸内的实际环境,使用高速摄像机对超临界二甲醚喷雾的外形轮廓及发展过程进行观察,并将其与跨临界二甲醚喷雾进行对比。结果表明,二甲醚喷雾在发展过程中发生了明显的卷状分裂,并且观察不到二次分裂现象;超临界二甲醚喷雾的外形轮廓及贯穿距离与跨临界喷雾并未有明显差别,但由于超临界二甲醚在涡轮增压环境中的扩散速率更快,因此其喷雾锥角更大,喷雾核心区的长度更短;两种喷射状态下的二甲醚在喷入定容容器后,其喷雾尖端的推进速率都会先急剧增大,然后在达到峰值后又急剧减小,最后在低速段保持相对稳定。

An experimental study of supercritical DME spray characteristics

To study the spray characteristics of supercritical dimethyl ether (DME), the cylinder temperature and pressure of turbocharged engines were simulated in a constant volume vessel and DME spray was observed with a high-speed camera. The shape and development process of supercritical DME spray were compared with those at temperatures below and above the critical point. It is found that DME spray shows a clear roll splitting in the development process and yet no secondary splitting. Outer shape and penetration length of supercritical DME spray are almost the same as those of transcritical DME spray; however, since supercritical DME spray diffuses faster than transcritical DME spray, the former has a slightly wider spray angle and shorter length of core spray area. When DME is injected into the constant volume vessel, the tip velocity of spray under the two injection conditions increases to the peak at first, then decreases sharply, and finally remains stable in the low velocity area.