Investigating practicability of using liquid fuel kerosene in pulse detonation rocket engine model

Our research has been done under a research project supported by NNSFC (National Natural Science Foundation of China). In the research plan we submitted for the project, we explained the possible ways and means of making using liquid fuel in pulse detonation rocket engine (PDRE) model practicable. Unlike conventional steady-state rocket engines, which use constant pressure combustion, PDREs utilize the high-energy release rate and thermodynamic characteristics of detonation waves to produce thrust. This enables PDREs to operate at higher thermodynamic efficiencies. Furthermore, since the reactants are injected into PDREs at relatively low pressures, the need for massive turbomachinery, as used in conventional steady-state liquid rocket engines, is eliminated. The utilization and performance of liquid hydrocarbon fuels used in a PDRE are being investigated, since these fuels are attractive for volume-limited aerospace systems. In our experiments, the PDRE test model utilized kerosene as the fuel, oxygen as oxidizer and nitrogen as purge gas. Solenoid valves were employed to control intermittent supplies of kerosene, oxygen and purge gas. The spark plug igniter used in these experiments had initiation energy of only around 50 mJ. The solenoid valves and spark plug were controlled by the control and ignition system. PDRE test model was 25 mm in inner diameter by 800 mm long. DDT (deflagration to detonation transition) enhancement device Shchelkin spiral was used in the test model. Three piezoelectric pressure transducers placed on the detonation tube at different locations from the thrust wall were used to measure pressure trace. The proof-of-principle experiments of liquid kerosene-oxygen were achieved successfully within an acceptable length (less than 0.7 m from the thrust wall) with only 50 mJ ignition energy. The obtained pressure ratio of detonation wave was close to that of C-J (Chapman-Jouguet) detonation. Under various frequencies, the detonation pressures were measured and analyzed. The experimental results show that the PDRE test model can produce fully developed detonation in a short distance of less than 0.7 m with only an ignition energy of 50 mJ.