A Reduced Order Model based on Large Eddy Simulation of Turbulent Combustion in the Hybrid Rocket Engine

¹ Elie Carafoli Dept. of Aerospace Sciences, University Politehnica of Bucharest, Ghe. Polizu Str., 011061 -Bucharest, ROMANIA
² Elie Carafoli Dept. of Aerospace Sciences, University Politehnica of Bucharest, Ghe. Polizu Str., 011061 -Bucharest, ROMANIA
³ Elie Carafoli Dept. of Aerospace Sciences, University Politehnica of Bucharest, Ghe. Polizu Str., 011061 -Bucharest, ROMANIA
⁴ Elie Carafoli Dept. of Aerospace Sciences, University Politehnica of Bucharest, Ghe. Polizu Str., 011061 -Bucharest, ROMANIA

Abstract

A combined method of large eddy simulations for non-premixed combustion in a turbulent boundary layer coupled with proper orthogonal decomposition of instantaneous velocity, pressure and temperature fields is developed in order to obtain a reduced order model. First, we investigate a channel turbulent reacting flow using Large Eddy Simulations (LES) technique. Polypropylene/O2 has been considered as fuel/oxidant pair. The turbulence-combustion interaction is based on a combination of finite rate/eddy dissipation model applied to a reduced chemical mechanism with four reactions. The LES numerical results are analyzed with respect to RANS simulations and with other reference data. The second part of the paper refers to the derivation of a Reduced Order Model (ROM) based on proper orthogonal decomposition (POD) technique for the unsteady flow field. In order to achieve that, the eigenmodes of the flow are computed from several snapshots of the instantaneous fields uniformly spaced and the most energetic ones are used to set up the Reduced Order Model. Constant regression rate of the fuel grain is considered. The flow and thermal fields obtained with ROMs are compared with the ones obtained from the full simulation and an analysis on the number of modes required to achieve the desired accuracy is presented.