Characterization of Combustion Processes of Fuel Sprays Injected into High-Temperature and High-Speed Airstream

对高温高速气流中煤油喷雾的特性过程进行了实验研究。燃烧室的内部具有70mm x 70mm的矩形横截面。在燃烧室横截面的中心处，从喷嘴向下一定距离（混合距离）处，设置了一个矩形钝体。今年的试验是由燃烧室两侧各喷入四股喷雾进行的。喷嘴在燃烧室两侧的位置改变了喷雾在气流中的分布。主要结果如下。(1)A火焰熄灭的临界煤油流量随气流温度先减小后增大，但变化不大。（2）当气流温度和煤油流量较高时，在混合距离（旋流喷嘴与海崖体之间）处发现喷雾自燃。随着气流温度的升高，自燃临界煤油流量减小，稳定燃烧范围变窄。（3）燃烧室中相对均匀的喷雾分布使火焰熄灭和自燃的临界煤油流量增大。由于自燃临界煤油流量随气流温度的增加大于火焰熄灭临界煤油流量随气流温度的增加，使得稳定燃烧范围变宽。（4）混合长度对火焰熄灭的临界煤油流量影响不大。混合长度的增加降低了自燃的临界煤油流量。

An experimental study was conducted on the characterization processes of kerosene sprays injected into a high-temperature and high-speed airstream. The interior of the combustor has a rectangular cross-section of 70mm x 70mm. A bluffbody with a rectangular shape was settled at the center of the cross section of the combustor which was a certain distance(mixing distance)down the airstream from the nozzle. The experiment in this year was made of the combustion of four sprays injected from each side of the combustor. A distribution of the sprays in the airstream was changed by the location of the nozzle on each side of the combustor. Main results obtained are as follows.(1)A critical kerosene flow rate for flame blow off was decreased and then increased with the airstream temperature, but the variation was small.(2)Spontaneous ignition of the sprays at the mixing distance(between the swirl nozzles and the bluff body)was found when both the airstream temperature and the kerosene flow rate were high. A decrease in a critical kerosene flow rate for the spontaneous ignition with an increase in the airstream temperature made stable combustion range narrow.(3)Relatively homogenizing a distribution of the sprays in the combustor increased the critical kerosene flow rates for both the flame blow off and the spontaneous ignition. A stable combusion range was made wide since the increase with the airstream temperature in the critical kerosene flow rate for the spontaneous ignition was larger than that for the flame blow off.(4)The mixing length did not have a large effect on the critical kerosene flow rate for the flame blow off. An increase in the mixing length reduced the critical kerosene flow rate for the spontaneous ignition.