EFFECTS OF EVAPORATING SPRAY ON NEAR-FIELD TURBULENCE CHARACTERISTICS IN A GAS TURBINE–LIKE MODEL COMBUSTOR

Abstract

Direct numerical simulation of lean fuel spray in a prevaporized, premixed model combustor is performed to investigate the effects of evaporating spray on turbulence characteristics under gas turbine-like conditions. The gas phase is solved in Eulerian frame and the droplets are tracked as Lagrangian particles. The evaporation process is described with a corrected infinite thermal conductivity model. The results show that evaporating spray that has almost completed evaporation in the premixing tube could significantly affect the local turbulent characteristic in the near-field area. With the existence of evaporating spray, the recirculation zones are evidently enhanced and expanded. For fluctuating fields, the increase in axial component indicates an intensive turbulent disturbance caused by evaporating spray. Further analysis of the energy spectrum shows that evaporating spray magnifies kinetic energy in the small scale. The evaporating spray globally increases the turbulent kinetic energy (TKE) along the radius. Through the budget of TKE, the detailed mechanism of TKE transport is observed. The convective transport and turbulent transport are enhanced noticeably while production and viscous dissipation are abated. For the subviscous dissipation terms, evaporating spray can significantly depress squared dilatation, thus reducing turbulence dissipation to internal energy. Evaporating spray influences turbulence in many aspects.