Operating Characteristics of Rotating Detonation Engine With High-Vapor-Pressure Liquid Fuel for Sounding Rocket Space Flight in 2027

Liquid propellants are widely used in rocket engines, and investigating the operational characteristics of RDEs using liquid propellants is essential for their practical application. In this study, combustion experiments were conducted on a single-annular RDE using liquid propane and liquid nitrous oxide as propellants, and its operational characteristics were evaluated. As a result, successful operation in the detonation mode was achieved with an operating frequency of 15–16 kHz. However, a gradual decrease in the propane mass flow rate was observed during combustion. This behavior was attributed to the possible occurrence of vapor lock in the propane injector feed lines caused by heat generated during combustion. To examine this possibility, the injector feed line wall temperature was calculated using the heat conduction equation under the assumptions of a one-dimensional semi-infinite solid, a constant incoming heat flux, and single-phase liquid flow in the injector. The results showed that for an incoming heat flux of q=0.2 MW/m2, the wall temperature near the injector outlet exceeds the boiling temperature of propane, indicating the potential for bubble formation at the injector outlet.