Assumed PDF Modeling of Turbulence Chemistry Interaction in Scramjet Combustors.

A multivariate assumed PDF approach together with finite-rate chemistry is used for the simulation of scramjet combustors. Because the combustor entrance conditions of scramjets at low flight Mach numbers (Ma ≈ 8) are close to the ignition limit of hydrogen air mixtures, detailed kinetic schemes are required and an accurate simulation of temperature and temperature fluctuations is essential. In the present paper, a lobed strut injector concept is used for hydrogen injection which enhances the mixing process by production of streamwise vorticity. The influence of the chosen combustor geometry on the mixing behaviour is investigated in this paper. Moreover a Mach 2 supersonic combustion experiment is simulated to investigate the influence of the chosen reaction mechanism and of the assumed PDF model. A detached flame is obtained and the predicted ignition length is a measure for the accuracy of the used kinetic scheme and the modeling of turbulence chemistry interaction. [ABSTRACT FROM AUTHOR]