Numerical simulation of three-dimension combustion in an annular combustor during a transient state

A numerical investigation of an annular combustor in a transient state (from idle to maximum) was conducted with commercial software FLUENT by adding the UDF(user-defined function) subroutines. Temperature field was studied by comparing with traditional method (which used steady simulation at some discrete operation conditions to approximate the transient state). The results show that: (1) there are large differences between transient and steady simulation at corresponding operation condition, the outlet temperature distribution of steady simulation is higher than the transient simulation; (2) the time step is a critical factor affecting the accuracy of transient simulation, a small time step could account for the close interaction with flow filed parameters of different times; (3) a hysteresis phenomenon during the transient state exists at the averaged outlet temperature in relation to fuel-air ratio.