Regression Rate Characterization of HTPB‐Paraffin Based Solid Fuels for Hybrid Rocket

Abstract

Hybrid rockets are entitled with unique features such as simplicity, thrust modulation, safety, and low cost compared to that of conventional liquid and solid rockets. Despite their distinct advantages, the polymeric solid fuels exhibit a low regression rate, which limits their potential applications for the various space missions. In this study, pure hydroxyl‐terminated polybutadiene (HTPB), paraffin wax, and blended HTPB‐paraffin solid fuels, namely 80P, 60P, 40P, 25P were characterized for ballistic performance. The viscosity, local regression rate, average regression rate and combustion chamber pressure of solid fuels were evaluated on a lab‐scale ballistic motor. It was found that the viscosity of blended fuels decreased with increasing the paraffin wt. % in the formulation. The local regression rates of blended fuels increased in the range of 0.53 mm/s to 1.58 mm/s at oxidizer mass flux range of 85 kg/m2s to 150 kg/m2s. The results indicate that increasing the wt.% of paraffin in the blend will enhance the average regression rate performance, besides suppressing the low‐pressure oscillations during steady‐state operation.

Combustion performance of hybrid rocket fuels loaded with MgB2 and carbon black additives

“…Such coating facilitates the easier removal of fuel grain after solidification of paraffin. Our previous study found that paraffin wax tends to volumetric shrinkage (15%e25%), depending on the grade of wax, upon solidification from liquid to a solid phase [24]. Therefore, during the fuel casting, the molten paraffin mixture was poured slowly and in a single stretch into casting mold to avoid air bubbles formations and any other discontinuities in the fuel grain.…”

Thermal, Viscosimetric and Thermomechanical Combined Assessment of Mixture Modelled Composite Fuels for Hybrid Propulsion

“…The quality of the fitted model stems from the in-situ measurement conditions, which included shear-thinning effects [38]. Accordingly, there were no interaction terms, de- Thermal, Viscosimetric and Thermomechanical Combined Assessment of Mixture Modelled Composite Fuels for Hybrid Propulsion spite the considerable shear stresses involved in the mixing step of the preparation method and the resulting partial miscibility level observed through melting and crystallization enthalpies [19].…”

Modelling of Hybrid Rocket Flow-Fields with Computational Fluid Dynamics

“…This type of rocket propulsion is attractive and provides many advantages over conventional liquid or solid rocket propulsion systems due to their low-cost, fuel handling simplicity, durability, throttling capability, and eco-friendly attributes [2][3][4][5][6][7][8]. It is easy to throttle the hybrid rocket engines by adjusting the oxidizer mass flow rate, which serves as ideal candidates for adjustable thrust rocket and is appropriate for all applications where rockets are used [9][10][11][12]. This is due to the versatility of the propellant, the wide range of performance, and the flexibility of the thrust [13].…”