气态/超临界态RP-3航空煤油喷嘴内部流动可视化研究

In order to study the flow characteristics of gaseous / supercritical RP-3 aviation kerosene in an injector，a transparent test piece simulating the converging internal passage of the injector was independently designed，visualization of flow structure was performed by shadowgraph images，and the phenomenon was analyzed by using one-dimensional flow analysis method. The visualization images of gaseous / supercritical RP-3 aviation kerosene flow structure of injector internal passage were obtained，and the expansion in the converging channel caused the density gradient，resulted in the change of the shape of the transparent area in the passage. The results revealed that the changes of injection temperature and pressure have influence on the supercritical and gaseous fuel flow characteristics in the converging internal passage. The phenomenon can be attributed to differences in axial and radial variations of fuel density under different operation conditions，therefore the transparent areas in different sizes or shapes were shown in the injector. In the axial direction，the greatest density variation occurred at the nozzle outlet，and change increased with the decrease of injection temperature and the increase of injection pressure，respectively. In the radially direction，due to the temperature boundary layer，the density changed near the nozzle wall，and the variation decreased with the decrease of injection temperature. At the near critical injection temperature，the transparent region under the condition of subcritical injection temperature is uniform along the axis，while the transparent region under the condition of supercritical injection temperature is shrinking along the axis.