Port diameter design of multiport solid fuel in hydrogen peroxide hybrid rockets

A feasibility study of the design of multiport solid fuel using the ratio of the nozzle throat area to the port area was performed in a hydrogen peroxide/high-density polyethylene hybrid rocket. The port diameters of the multiport solid fuel according to the change of the number of ports were designed by setting the ratio of the nozzle throat area to the port area at 0.25, 0.3, 0.5, and 1. To obtain the design point of the multiport solid fuel, the final port diameter and performance parameters were analyzed using a numerical estimation code based on the regression rate equation. The numerical estimation indicated that the solid fuel with nine circular ports with a length of 400 mm, and a port diameter designed with ratio of 0.5 between the nozzle throat area and the port area, had an oxidizer-to-fuel ratio (O/F) close to the design value and high specific impulse efficiency. To verify the value calculated using the numerical estimation, a 2500-N-class hydrogen peroxide/high-density polyethylene hybrid rocket with multiport solid fuel was designed, and experiments were performed. The specific impulse and overall regression rate calculated from the experiments and numerical estimation were compared. The maximum differences of less than 10.7% and 4.38% were observed in the comparison. Based on the small difference, the estimation results calculated using numerical estimation at ratios (the nozzle throat area to the port area) of 0.25, 0.3, 0.5, and 1 were demonstrated. The design method of the multiport solid fuel in a hydrogen peroxide/high-density polyethylene hybrid rocket using the ratio of the nozzle throat area to the port area and the numerical estimation based on the regression rate equation was feasible.