An experimental investigation is carried out on an inverse diffusion flame (IDF) burners having central air jet and being surrounded by fuel jets for an impingement heat transfer. A thorough investigation has been performed to study the effects of the diameter of air jet, orientation of fuel jets and swirl in the central air jet on an inverse diffusion flame shapes, mainly on heat transfer characteristics. The twisted tapes of twist ratios (TR) 2.5 and 3.75 (corresponding to the swirl numbers of 0.62 and 0.41) are used for two different IDF burners to create a swirling flame jet. A comparison is made between the two IDF burners for with and without swirl conditions operating at a fixed air jet Reynolds number (Re a ) of 2000 and equivalence ratio ( ϕ ) varying from 0.4 to 1.4 for a fixed burner surface to impingement plate distance of 20 mm. It is observed that for the same operating conditions, diameter of an air jet and orientation of fuel jets impart a substantial change in an inverse diffusion flame behavior by enhancing air–fuel mixing intensity. The experimental results show that the burner with smaller air jet diameter along with swirl produces a higher heat transfer rate to an impingement plate. An experimental work provides a contribution to improve a combustion characteristic of IDF for impingement heating on a flat surface.

中文翻译：

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燃烧器几何形状对带涡流冲击逆扩散火焰射流传热特性的影响

对具有中央空气射流并被燃料射流包围以进行冲击传热的逆向扩散火焰 (IDF) 燃烧器进行了实验研究。为了研究空气射流的直径、燃料射流的方向和中央空气射流中的漩涡对逆扩散火焰形状的影响，主要是对传热特性的影响，已经进行了彻底的调查。捻度 (TR) 为 2.5 和 3.75（对应于 0.62 和 0.41 的旋流数）的扭曲带用于两种不同的 IDF 燃烧器以产生旋流火焰射流。在固定喷气雷诺数 (Re a ) 为 2000 和当量比 ( ϕ ) 从 0.4 到 1.4 的情况下，在有和没有涡流条件下对两个 IDF 燃烧器进行比较，固定燃烧器表面到冲击板距离为20 毫米。观察到，对于相同的操作条件，空气射流的直径和燃料射流的方向通过增强空气-燃料混合强度使逆扩散火焰行为发生实质性变化。实验结果表明，具有较小空气射流直径和涡流的燃烧器对冲击板产生较高的传热率。一项实验工作有助于改善 IDF 的燃烧特性，以在平坦表面上进行冲击加热。实验结果表明，具有较小空气射流直径和涡流的燃烧器对冲击板产生较高的传热率。一项实验工作有助于改善 IDF 的燃烧特性，以在平坦表面上进行冲击加热。实验结果表明，具有较小空气射流直径和涡流的燃烧器对冲击板产生较高的传热率。一项实验工作有助于改善 IDF 的燃烧特性，以在平坦表面上进行冲击加热。