Characterization of impingement region from an impinging inverse diffusion flame jet

摘要

This investigation is on the characterization of the impingement region of an inverse diffusion flame (IDF) jet. The length of the jet impingement region (Li), the characteristics of the wall gauge static pressure (△P_W) and heat flux (q') in the impingement region, were studied. A similarity is found between the radial distributions of APW and q', which enables a comparative study on △P_W and q'. The effects of the non-dimensional nozzle-to-plate distance (H/d_a), the flame equivalence ratio (φ), and the air port diameter (d_a) on △P_W and q' are studied comparatively. It is found that while the distribution curves of △P_W are always bell-shaped with a maximum stagnation pressure (△P_S), those of q' vary in shape under different H/d_a. The maximum heat flux {q'_(max)), the average heat flux (qi), the distributions of the nondimensional wall static pressure (△P_W/△P_S) and the nondimensional heat flux (q'/q'_(max)), in the impingement region, are studied. The thermal efficiency of the IDF impingement heating system (η_(th)) is evaluated and compared under different operational conditions. The current investigation provides the insights into the characteristics of the jet impingement region by correlating the heat transfer performance to the hydro-dynamic behaviour, which facilitates the optimization of the jet impingement system design and operation.