Development of Rocket Engine with Continuously Rotating Detonation supplied by Liquid Propellants
Creators: name:  M. KAWALEC 
name:   P. WOLANSKI 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: PROPULSION PHYSICS
ELECTRICAL PROPULSION
ADVANCED PROPULSION

description: Research on application of continuously rotating detonation (CRD) to propulsion systems is now carried out at many laboratories [1-5]. Most of those research concerns research of gaseous propellants and there is a growing numbers of research of CRD for liquid fuels with air or oxygen mixtures and also laboratory tests of RDE supply by liquid propellants. The extensive survey of recent CRD research can be found in [6]. Recently at the Institute of Aviation in Warsaw research were initiated on utilizing liquid propellants on small size rocket engines with CRD [7]. As a propellants Nitrous Oxide (N2O) and Propane (C3H8) were used. Initial, short duration tests, were carried out in annular combustion chamber equipped with slit nozzle as well as and disc shape combustion chamber equipped with classical cone shaped nozzle. The stand test was equipped with pressure sensors for measuring fast changing pressure as well as for measuring average pressure in combustion chamber. Records of quick changing pressures allows to assess stability of detonation process. During those tests thrust was also measured and specific impulse was calculated. Disc shaped combustion chamber was much shorter, lighter and more compact than annular one. The stable detonation process was achieved for wide spectrum of mixture composition. The influence of the mass flow ratio was also checked. However the velocity of detonation waves and values of the pressures was similar for both annular and disk combustion chamber, while the performance (Isp) of the disc chamber exceeded the annular one. 81% of the theoretical value of impulse specific for the disc and conical nozzle arrangement and 66% for the annular system with a slot nozzle achieved. It should be mentioned that both engines were not cooled, and utilized only heat sink protection from high temperature detonation products. This however, remove significant amount of energy, and as results decreased measured value of specific impulse. As the results of those initial tests the new laboratory rocket engine was build and tested. The shape of the disc chamber has been slightly changed to a conical one with a small cone angle. The same conical nozzle was kept. Another type of cooling system has also been introduced - the regenerative cooling. The conical chamber from one site is cooled by liquid propane and from other site by liquid nitrous oxide. To initiate detonative combustion in chambers supplied by N2O- C3H8 mixture, the high temperature pyrotechnic igniter was use. The engine constructed in this way obtained 95% of the theoretical value impulse. This engine was then used as a propulsion for a small research rocket. A successful rocket test was carried out at a military training ground near Warsaw [8]. More research are underway and will be reported during presentation at the conference.