Effect on the performance of a hybrid rocket using AP in the PVC and HTPB-based hybrid fuel

• AP is added in limited quantity to hybrid fuel for improving performance. • Regression rate increased with AP addition to HTPB while PVC fuel gave no change. • Pressure, thrust and efficiency increased when AP was added in the HTPB fuel. • Relative improvement of performance with AP was lower with PVC than HTPB fuel. • Addition of AP to HTPB and PVC fuel gave uniform burning along the length of grain. Hybrid rocket is a type of chemical rocket propulsion system where the fuel and the oxidizer are stored separated and in different state of aggregation. Typically, the fuel is in the solid state and the oxidizer is either in the liquid or gaseous state. It offers various advantages over other type of chemical rockets such as throattability, controllability and reduced complexity. It also has some drawbacks such as low regression rate, poor combustion efficiency, higher sliver losses, etc. Various methods have been adopted to overcome these drawbacks and improve the performance of hybrid rocket. The present study focus on the improvement of regression rate with the addition of oxidizer particles in fuel content. Ammonium Perchlorate is used as an additive in Hydroxyl Terminated Polybutadiene (HTPB) and Poly Vinyl Chloride (PVC) based fuel grain. From the experimentations, it was observed that the thrust, pressure and regression rate of the HTPB fuel grain with additive have higher improvement than with the PVC based fuel grain. The sliver losses are also reduced due to uniform burning after addition of oxidizer in fuel grain. The overall study strongly suggests that addition of oxidizer in limited quantity can be used to overcome the drawbacks of hybrid propellant rocket.