Flow visualization of cryogenic spray from a movable pintle injector

Abstract

Pintle injector has the advantages of wide throttle-ability by sustaining high combustion efficiency and weight lightening by replacing multi-injector elements with a single injector element. However, compared to typical injectors with a fixed shape, like shear coaxial or coaxial swirl injector, there are many complex variables owing to the moving parts. In this study, using cryogenic liquid nitrogen and gaseous nitrogen as simulants, experiments on cryogenic nitrogen spray visualization were performed to simulate cryogenic oxygen and gaseous methane combustion experiments. Experimental conditions were varied by changing the pintle tip angle, pintle opening distance, and simulant supplying pressure. With the visualization images, the spray angle of cryogenic spray was obtained and compared with the previous empirical equations. The former empirical equation between total momentum ratio and spray angle is not well matched, but the other equation between velocity ratio and spray angle fits well with experimental result, through modification of parameter.