Structure and dynamics of cryogenic flames at supercritical pressure
Résumé
A detailed understanding of liquid propellant combustion is necessary for the development of improved and more reliable propulsion systems. This article describes experimental investigations aimed at providing such a fundamental basis for design and engineering of combustion components. It reports recent applications of imaging techniques to cryogenic combustion at high pressure. The flame structure is investigated in the transcritical range where the pressure exceeds the critical pressure of oxygen (p > p(c)(O-2 = 5.04 MPa)) but the temperature of the injected liquid oxygen is below its critical value (T-O2 < T-c(O-2) = 154K. Data obtained from imaging of OH* radicals emission, CH* radicals emission in the case of LOx/GCH(4) flames and backlighting provide a detailed view of the flame structure for a set of injection conditions. The data may be used to guide numerical modelling of transcritical flames and the theoretical and numerical analysis of the stabilization process. Calculations of the flame edge are used to illustrate this aspect. Results obtained may also be employed to devise engineering modelling tools and methodologies for component development aimed at improved efficiency and augmented reliability.