Effusion cooling characteristics of a model combustor liner at non-reacting/reacting flow conditions

Detailed effusion cooling feature on both inner and outer liner of a scaled annular combustor equipped with three axial swirlers has been investigated experimentally under both non-reacting and reacting flow conditions. The main flow is electrically heated for non-reacting cases, while methane-air premixed combustion is performed for the reacting conditions. Temperature distribution on the target bended plates with 7 rows of cooling holes in an in-line layout is captured by infrared thermography, and the overall cooling effectiveness is analyzed. Effects of nominal coolant to mainstream flowrate ratio and equivalence ratio are evaluated respectively. Non-reacting results show that the macro rotational flow generated by the swirl flows interacts with cooling film, leading to circumferentially non-symmetric cooling protection on both liners. At reacting conditions, stagnation of the high temperature flame impinging on the liner wall locates at X/D range of 0.4-0.5, which has not been observed in non-reacting experiments. Outer liner obtains better cooling protection than inner liner when reaction is activated. The effect of equivalence ratio is surveyed at Φ = 0.7, 0.8, 0.9, 1.0 and 1.1. This work highlights the significance of combustion in evaluating the effusion cooling performance on the real annular combustor liners, providing more accurate prediction compared to the conventional non-reacting methods.