Abstract

Modern combustor design optimization is contingent on the accurate characterization of the combustor flame side heat loads. Knowledge of regions of high and low heat loads on the liner wall helps designers optimize the cooling designs. The present work focuses on the experimental measurement of the transient heat load along a fused silica (quartz) optical can combustor under reacting conditions for a swirl stabilized premixed methane-air flame. Equivalence ratio was varied from 0.55 to 0.65. Reynolds number based on combustor diameter was varied from 12500 to 18000, where the preheated air temperature was approximately 373 K. The percentage of pilot fuel was varied from 6% to 10% of the main fuel flow rate. Inner and outer walls of the liner were painted with a high temperature flat black paint with an azimuthal offset to aid in infrared measurement of the wall temperature using an infrared camera. Particle Image Velocimetry (PIV) was employed to visualize the flow field for various reacting conditions studied in this work. Based on the heat transfer study, a detailed report of transient heat load along the length of the liner wall for varying reacting conditions has been presented here. The location of impingement of the flame onto the liner and velocity of the flow field were obtained from PIV measurements. Wall heat load at various planes along the length of the liner have been presented. Repeatability of this transient experiment was within 10% between eight different runs for various locations along the length of the liner, except for the region close to flame impingement zone. In the impingement zone, liner heat load varied by about 25% between different runs. It was observed that the change in heat load upstream of the location of impingement on the liner was insignificant with change in pilot ratio as the system tends towards a steady state, contrary to the regions downstream. Higher Reynolds number and equivalence ratios increased the heat load on the liner as expected.

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