超临界燃料在喷嘴附近的相变和流动过程

To explore the supercritical hydrocarbon fuel injection characteristics, the phase transition and flow process of supercritical n-decane/n-heptane/n-pentane mixtures injected into stationary atmospheric environment were studied by experimental and one-dimensional analysis method, and fuel phase transition path near the injector exit, phase transition boundary and one-dimensional flow parameters distribution inside the injector were obtained. The results revealed that phase transition and fuel condensation phenomenon occur when supercritical n-decane/n-heptane/n-pentane mixtures injected near the critical temperature. The condensation processes of fuel mixture occur within a certain temperature range and complete condensation occurs at the injection temperature of 510K under the supercritical injection pressure. The phase transition boundary line does not coincide with the phase boundary line. When the supercritical n-decane/n-heptane/n-pentane mixtures injected into stationary atmospheric environment, the velocity of the mixtures reaches the local sound speed at the injector exit, the ratio of local static pressure to injection pressure is about 0.64 and the ratio of local static temperature to injection temperature is above 0.97 in present test conditions. The one-dimensional flow parameter distributions are roughly coincident at different injection conditions, and the analysis results showed that the specific heat ratio and compressibility factor have significant influences on the distribution of one-dimensional flow parameters.