Numerical investigation of two-phase spray combustion performance for LPP low-emission combustor

Two-phase spray combustion flow field, temperature field and pollution emission performance of lean premixed prevaporized (LPP) low-emission combustor were calculated by software of Fluent. When the structure of pilot swirler and the inlet condition of LPP low-emission combustor were kept unchanged, influences of different primary swirler angles on combustion flow field, temperature field and pollution emission were investigated. Standard k-ε model was applied to simulate turbulent viscosity; fuel droplet trajectories were modeled by discrete phase model; non-premixed chemical equilibrium model was used to simulate the chemical reaction rates. Numerical results are as follow: (1) There are obvious primary recirculation zone, corner recirculation zone and lip recirculation zone in LPP low-emission combustor head. (2) The shape of primary recirculation zone is olive, and the length of primary recirculation zone is very long. With the increase of primary swirler angle, the primary recirculation zone becomes fatter and shorter, and the area of corner recirculation zone becomes smaller. (3) With the increase of primary swirler angle, the pressure loss will increase. (4) The production rate of thermal NOx is directly related with the area of temperature over 1950K and the highest temperature of gas. Near the flame front of pilot swirler and primary swirler, because of the high temperature, it is the main production area of thermal NOx. (5) With the increase of primary swirler angle, outlet temperature distribution factor increases firstly and then decreases. When the primary swirler angle is 45 degrees (just C project), outlet temperature distribution factor is the least, which means that the outlet temperature distribution is most uniform. (6) Under the same case, the combustion performance of C project is best.