Heat transfer distribution for impinging methane–air premixed flame jets

• IHCP technique to obtain local heat flux distribution using thermal camera.
• Adiabatic wall temperature and heat transfer coefficient are given.
• Circular, square and rectangular burners are used.
• Axis switching is observed in non-circular burners.
• Correlations for local Nusselt number and effectiveness are given.

Heat transfer by flame jet impingement is extensively used in industrial and domestic heating applications. The present experimental study proposes the application of an inverse heat conduction (IHCP) technique to obtain the heat flux distribution for methane–air premixed flame jet impinging on a flat plate. The heat flux distribution is studied for burner tubes of circular shape (d = 10 mm and 8.75 mm), square shape (width = 10 mm and 7.65 mm) and rectangular shape (19 mm × 9 mm). Methane–air premixed flame jet of Reynolds number varying from 600 to 2200 and an equivalence ratio of 1 is considered. The nozzle to burner tip distance is varied from 2 to 6. Axis switching is observed for non-circular shaped burner flame jets. Correlations for local Nusselt number and effectiveness distribution are proposed for circular and square burners by direct measurement of the adiabatic wall temperature. The heat transfer coefficients and adiabatic wall temperatures are validated with the experimental heat flux data available in the literature. The non-dimensional flame premixed cone height (ratio of flame premixed cone height to the distance of the burner tip from the impingement wall) alone governs the Nusselt number and effectiveness.