Performance of Mixture-Ratio-Controlled Hybrid Rockets for Nominal Fuel Regression

What is it about?

O/F shift in hybrid rocket propulsion is defined as the shift in oxidizer-to-fuel ratio. The purpose of this study is to challenge the previous conclusion that performance loss due to O/F shifts is negligible except for deep throttling. This paper challenged this conclusion by considering other paths via which O/F shifts affect the performance of rockets such as combustion efficiency and throat erosion. The effects were evaluated by the comparison of the performance between O/F-controlled and O/F-uncontrolled hybrid rockets using flight simulations of three scales of vertically launched sounding rockets under the assumption of nominal fuel regression characteristics. The combustion efficiency and nozzle throat erosion were modeled to depend on O/F ratio. This study found that the improvement of the combustion efficiency due to the O/F control had the secondary importance of up to 24.3% of the total increase for the smallest scale of rocket with a gross mass of 233 kg in the simulations.

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