The decoupling analysis of flame impingement heat transfer using field synergy principle

• The shorter the flame, the higher the heat transfer. • Establish a coupled model: Q w = Q Φ + Q s. • Maximal Q s occurs when plate contacts the flame tip. • Convex-plates optimize the synergistic angle β . In this study, numerical simulations were employed to explore the physical and chemical processes of flame-wall impingement using the field synergy principle, revealing the coupling mechanism of flame impingement heat transfer. The research demonstrates that both hydrogen-enriched biogas ( R H = 0.1 & 0.2) and elevated initial temperatures (400–500 K) can enhance impingement heat transfer by shortening the flame height of biogas. The total heat transfer rate Q w can be decoupled into Q Φ (inversely proportional to the nozzle-to-plate distance) and Q s (maximized when the flame tip contacts the plate). Compared to a flat plate, a convex-shaped plate generates a secondary impingement effect in non-stagnation zones through its curved structure, optimizing the synergy angle from π/2 to a larger value. This creates localized enhancement regions, improving overall thermal efficiency by 3.9 %. Therefore, in household or industrial stoves, an integrated approach combining hydrogen-enriched fuel, convex-shaped plates, and distance adjustment can achieve higher heat transfer efficiency.