Heat transfer and flow characteristics inside a gas turbine combustor

Abstract

Heat transfer and flow characteristics inside a typical can-annulus gas turbine combustor are investigated. This is the first study in a public domain to focus on the convective heat loads to combustor liner due to swirling flow generated by swirler nozzles. The objectives of this study are to physically design an experimental combustor test model, to perform local accurate heat transfer and flow measurements, and to better understand the fundamental thermo-fluid dynamic effects inside a combustor equipped with a swirler nozzle provided by Solar Turbines Inc. The local temperature and heat transfer distribution were determined to locate the heat transfer peak region and compared with velocity flow field and turbulent intensity distributions. The actual test model is 5-times the original 8” (20.32cm) diameter prototype to simulate realistic engine operating conditions and also provide high resolution measurements. Experiments were performed at two flow Reynolds Numbers (500k and 662k) to further investigate the effects of Reynolds Number on the heat transfer peak locations and velocity flow field distributions. The heat transfer investigation was performed using the steady-state Infrared Thermography technique. Six identical surface heater foils were used to simulate the constant-heat-flux boundary condition, and the Infrared Thermal Imaging system was used to capture the real-time steady-state temperature distribution at the combustor liner wall. The results show that the heat transfer peak regions at different Reynolds numbers occur at the same exact location. Investigations on flow characteristics were also performed to compare the velocity flow field and turbulent intensity distributions with the heat transfer results. Using TSI Constant Temperature Anemometry technique, with a highly sensitive hot-wire dual sensor X-probe and a rigidity reinforced probe support system; the 3-dimensional complex swirling velocity flow field was measured. The heat transfer and flow field results are in good agreement with each other. The peak locations of local turbulent intensity and heat transfer regions overlap at the exact same location for both Re=500k and Re=662k cases respectively. The overall results show that the heat transfer peak location on a gas turbine combustor liner strongly depends on the peak location of turbulent intensity of the swirling flow and not the maximum value of total velocity. In addition, the results also show that the peak locations are unaffected by the flow Reynolds number or flow rate. This is true within the tested range of Re=500k and 662k.