Hybrid Lean Blowout Prediction Methodology with Reactive Flow Simulation

Abstract

ABSTRACTRobust and accurate prediction tools are required at a component design stage in order to choose the most suitable geometry. Semi-empirical correlations are sufficiently robust to predict lean blowout (LBO) performance of combustors; however, their accuracy is limited due to insufficient modeling depth, which can relate geometric variation with LBO performance. The flame volume concept, which is dynamically linked to the flow structures, spatial interaction of mixing jets, heat evolution, and dissipation in the primary zone, has brought improvements. Nevertheless, its estimation is a challenging task. Previously, it was evaluated from the flammable volume estimation within a cold flow simulation that it needed a correction step. This work extends the hybrid LBO prediction to reactive flow simulations with Reynolds Averaged Navier–Stokes simulations in Fluent platform. In this study, 10 geometric configurations were investigated and their experimental data was presented. Relationship between the flow structures in a primary zone and the global LBO stability was successfully described by defining a ‘heat content’ parameter. Flame identification criterion was also established and effectively utilized for the flame-volume estimation within reactive flow simulations. As a result, the correction step was eliminated and led to reduction of the iteration loop. Comparison of the simulated and experimental flame volume reported maximum and average errors of ±15% and ±5%, respectively. The improvement was mainly attributed to the inclusion of reactive flow simulations and the flame identification criterion.