Parametric investigation on similarity and scale effects in hybrid motors

Similarity analysis reported for hybrid rocket motors has indicated that in order to correctly interpret the experimental results and extrapolate them to different-scale systems, the main operating conditions to be maintained are: geometric similarity, same oxidizer and fuel combination, and scaling of the oxidizer flow rate in proportion to the motor port diameter. An experimental investigation has been conducted on polymethylmethacrylate/gaseous oxygen hybrid rocket system to verify the reported analysis. The results of the experiments have demonstrated fairly good agreement between the theoretical prediction and the experimental results of key operating parameters, such as fuel regression rate, and thrust, verifying the reported similarity model and its resulting scaling rules.