PIV characterization of supersonic two-phase flow in a solid rocket motor using a visual nozzle

The performance of a solid rocket motor directly determines the range and speed of weapon systems. As a critical component of the motor, the nozzle plays a significant role. The velocity distribution of the internal supersonic two-phase flow field significantly influences motor performance. However, experimental investigations on the velocity characteristics of the two-phase flow fields for solid rocket motor nozzles remain relatively scarce. To obtain the velocity distribution of the supersonic two-phase flow field within the nozzle of a solid rocket motor, a visual nozzle was designed to enable direct observation of the internal flow. Experimental systems were established for both cold-flow experiments and hot-firing experiments of solid propellant motors. Using the particle image velocimetry (PIV) technique, online measurements of the nozzle flow field velocity distribution were carried out under both conditions. The results indicate that the visual nozzle sealed with quartz glass enables online velocity measurements inside the nozzle under cold-flow conditions, with the maximum time-averaged axial velocity reaching 600 m/s. Under hot-firing conditions, the visual nozzle sealed with a truncated metal cover plate allows successful online velocity measurements of the internal flow field, with the maximum time-averaged axial velocity reaching 1000 m/s.