Heat transfer characteristics of three interacting methane/air flame jets impinging on a flat surface

Abstract

An experimental study has been conducted for three interacting methane/air flame jets (arranged in a triangular configuration) impinging normally on a flat surface. Surface heat flux distributions have been determined for various dimensionless inter-jet spacings ( S/ d = 3, 4, 6 and 7.58) and separation distances between the exit plane of the burners and the target plate ( H/ d = 2, 2.6, 5 and 7). All experiments were conducted for stoichiometric mixture at a Reynolds number of 800. The surface heat flux distributions were intimately related to flame shapes. For small inter-jet spacings and small separation distances, flames were deflected outward from the centroid of the triangular arrangement due to strong interaction between the jets. The heating was quite non-uniform at very large inter-jet spacings. Zones of low heat flux were obtained when the tip of inner reaction zones were intercepted by the plate ( H/ d = 2). There were sharp peaks in the heat flux distribution when the tips of the inner reaction zones just touched the impingement surface ( H/ d = 2.6). Heat flux distribution was non-uniform at small separation distances ( H/ d = 2 and 2.6). For the system of flame jets under consideration, the optimum configuration, considering the magnitude of the average heat flux and the uniformity in the heat flux distribution, was corresponding to H/ d = 5 and S/ d = 3.