超临界燃料输送系统中甲烷/氮输运特性试验研究

Experimental Study on Transportation Characteristic of Methane/Nitrogen in Supercritical Transport System

关键词:  超燃冲压发动机  超临界输送  甲烷  输运特性

Key words:  Scramjet  Supercritical transportation  Methane  Transportation characteristic

摘要:

为在确知组分条件下，获得不同小分子碳氢燃料的输运、喷射与燃烧特性数据，建立了一套可用于单组分和多组分超临界小分子碳氢燃料输送的系统。该系统采用先加压再加热的工作模式，使预知组分的小分子碳氢燃料达到喷前状态。利用氮作为输送介质进行了系统校验，试验中所获得的不同位置压力、温度随时间的变化数据表明，系统实现了氮流量及输送条件的稳定控制；在所研究的参数范围内，在下游出口获得了氮的不同相态；上下游两级喉道内氮流量的计算结果相对偏差≤±3%，说明两级喉道内氮的流量匹配性较好。在较大参数变化范围内，试验研究了甲烷在系统中的输运特性。甲烷的相态和流量分析结果表明，当喉部处相态位于气相时，可以按理想气体等熵流动计算流量，所得结果与国家标准提供方法相差小于±1%；当甲烷在上游喉道的喉部处于超临界相、在下游喉道的喉部处于气相时，两喉道流量计算结果相差8%～17%。该系统可以实现氮/甲烷流量大于100g/s，喷前压力大于5MPa，喷前温度高于450K条件下的稳定输送。

Abstract:

In order to investigate the transportation，injetion and combustion characteristics of the supercritical small molecular hydrocarbon mixtures with different compositions，a system was developed for supercritical mono- or multi-component hydrocarbons transportation. In the system，the small molecular fuels were pressurized to a supercritical pressure and then heated to a supercritical temperature before injection. Nitrogen (as the injectant)transportation tests were undertaken to validate the experimental system. The curves of pressure and temperature versus time at different positions were acquired in the transportation tests and the results indicated that the nitrogen flowrate and transport conditions were stably controlled. In the studied parameter range，the different nitrogen phase states at the downstream exit were acquired. The nitrogen mass flowrates in the two throats were calculated and compared with each other，the relative deviation values were not greater than ±3%，which indicated good match of nitrogen flowrate between the two throats. After that，the transportation characteristics of methane were experimentally studied under a wide parameter range. The analytical results from methane phase diagrams and flowrates were obtained，which indicated that the methane flowrate could be calculated with the ideal gas isentropic flow when methane were in gas states in the throats，and that the differences between the methane flowrates which were respectively calculated with ideal gas isentropic flow and national standard were less than ±1%. In addition，as methane were in supercritical states in the upstream throat and were relatively in gas states in the downstream throat，the relative deviation values of the mass flowrates between the two throats were between 8% and 17%. For both nitrogen and methane，the stable transportation processes for the conditions of flowrate larger than 100g/s，jetting pressure greater than 5MPa and jetting temperature higher than 450K are achieved.