Experimental study on the influence of inlet velocity and fuel/air ratio on outlet temperature profile performance in a turboshaft engine combustor

This paper presents an experimental study on the influence of inlet velocity and fuel/air ratio (FAR) on the outlet temperature profile in a mixed-flow trapped vortex combustor (MTVC) working with RP-3 liquid fuel. This new MTVC is using a single cavity to stabilize flames for turboshaft engine. Temperature profile performances, such as temperature non-uniformity, radial temperature profile, profile factor (RTDF) and pattern factor (OTDF), were examined at atmospheric pressure on a fan-shaped test rig at different inlet velocities and fuel/air ratios. By analyzing the temperature pattern in the cavity, the reason for the characteristic law of the outlet temperature profile is obtained. The results indicate that the MTVC has achieved a satisfactory temperature profile, which can meet the requirements of the turbine. The radial temperature profile at combustor outlet is not a flat straight line, showing a pattern of high temperature in the middle of combustor outlet and low temperature at both ends of combustor outlet. The peak temperature is 0.6 times the height of combustor outlet. The high temperature zone with a constant FAR lean towards the top of the outlet center, and the temperature non-uniformity, OTDF and RTDF increase with increasing velocity. However, the high temperature zone approaches the outlet axis at a constant velocity as FAR changes. The temperature non-uniformity decreases with an increases of FAR. There is an optimal velocity where OTDF and RTDF pass through a minimum value. A decrease or increase in velocity beyond this optimal velocity results in an increase in both OTDF and RTDF. This mainly depends on the fuel distribution, the air jet mixing, the local FAR in cavity, and the location of high-temperature products in combustor outlet.