Two-phase flow numerical calculation of H₂O₂/HTPB hybrid rocket engine with diaphragm in grain

The effect of diaphragm in grain on combustion performance of hybrid rocket engine was studied. The standard φ 100 mm hybrid rocket engine of Beijing University of Aeronautics and Astronautics was selected as a computational model, and 98% hydrogen peroxide(H₂O₂)/hydroxyl terminated polybutadiene (HTPB) was combined as propellant; different hole diameters of diaphragm setting at different grain positions were computed by 2-D axial symmetry and gas-liquid two-phase flow model. The results show that smaller diameter of diaphragm hole and the diaphragm setting at positions ranging from 50% to 70% of grain length can obtain the largest averaged regression rate of fuel and the highest combustion efficiency. This conclusion will provide a theory evidence for design of the diaphragm.