Experimental investigation on heat transfer characteristics of an annual jet flame in a pore-array spray gun

Oxyacetylene ablation is widely used to assess high-temperature thermal protection materials. This study investigated the heat transfer characteristics of an oxyacetylene spray gun structured with pore arrays for long-term ablation. The effects of oxyacetylene test parameters (Reynolds number (Re), equivalence ratio (φ), and ablation distance (H)) on the flame shape and heat flux distribution were studied to explore heat transfer behavior. Subsequently, ablation experiments were performed to verify the heat transfer characteristics under different operating conditions. The following conclusions were obtained: (1) The flame shape is characterized by the base flame, flame neck, and main flame, depending on the mixedness of the inner and outer jets. (2) The position of peak heat flux occurred in the radial direction, and the peak heat flux reached 4792 kW/m² when the Reynolds number, impingement distance, and equivalence ratio were 77700, 20 mm, and 0.72, respectively. (3) The suggested ablation distance is H_s = (57.65–61.98) × [MR]^−0.56 (MR: momentum ratio). This study provides useful data for high-enthalpy, long-duration ablation.