Experimental Investigations of Tapered Fuel Regression Rate of Hybrid Rocket Motor

Abstract

The purpose of this research is to investigate a way of improving the non uniformity of the local regression rate in a cylindrical or multiport grain which is an inherent disadvantage of hybrid rocket combustion. A lab scale Hybrid Rocket Motors (HRM) using tapered solid grain (convergent or divergent) having different taper angles is opted for our study. The non uniform local regression rate can not only cause the slivers of solid fuel, but also cause early port merging in the pre and aft section of the multiport grain during combustion. Experiments are conducted to confirm whether taper angles can relax the non uniformity of the local regression rate or influence the performance of lab scale HRMs. In this study, the steeping method is used to measure the accurate local regression rate of tapered grain with taper angles of 1 and 2 degrees. Combustion characteristics such as the overall regression rate and the characteristic velocities are compared with those of cylindrical grain to see taper angles effects on the performance. The possibility of improving the overall regression rate and the non uniformity of local regression rate is discussed.