Effect of Using Fractals as Grain Configuration on the Performance of Solid Rocket Motors

Abstract

Grain design is a very crucial consideration for determining the performance of solid propellant rocket motors. A rocket’s performance and combustion characteristics (thrust profile, chamber pressure variation, propellant mass flow rate, and sliver among other important performance parameters) depend very strongly on the grain configuration. We propose fractal shapes (Koch star, Koch snowflake, Gosper, and Cesaro) as new port geometries and theoretically predict their performance using simulations based on the fast-marching method implemented in the open-source software Open-Motor. The initial thrust for fractal geometry grains was found to be significantly higher than the commonly used industry standard BATES and Finosyl ports. The fractal grains also showed a significant decrease in sliver as compared to the Finocyl port that is generally used to increase performance as compared to the circular BATES ports. Especially, The Koch snowflake port had a drastically lower sliver. These new grain geometries proposed in this work can be used for applications in which low initiation and ignition times along with high initial thrust are crucial. Moreover, these geometries can improve the performance of the solid rocket motor (SRM) owing to their better regression characteristics which promise complete utilization of the entire grain web.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Soham Bhattacharya

Soham Bhattacharya is a third-year undergraduate student at the Department of Mechanical Engineering, Jadavpur University, Kolkata, India. His primary research interests lie in the field of aerospace propulsion, combustion stability, and fluid mechanics. He is a part of a research project studying the multifractal analysis of combustion stability.

Raghav Mundhra

Raghav Mundhra finished his B.E. in Mechanical Engineering from Jadavpur University, Kolkata, India in 2019. Currently, he is pursuing his MS in Mechanical Engineering from Indian Institute of Technology, Kharagpur, India. His primary research interests lie in the fields of aerospace propulsion, fluid mechanics, and thermodynamics. He has authored three conference papers.