Abstract
Flow and heat/mass transfer characteristics for the array impinging jets with effusion holes are investigated and also the effects of the effusion hole depth on heat/mass transfer characteristics using protruding effusion holes are investigated. For these purposes, a naphthalene sublimation method is employed to determine local heat/mass transfer coefficients on the target surface using a heat and mass transfer analogy. A numerical analysis using a commercial program (FLUENT) is also performed to analyze the flow characteristics. For small gap distances, heat/mass transfer coefficients without effusion holes are very non-uniform due to the strong effects of crossflow and re-entrainments of spent air. However, more uniform and higher heat/mass transfer coefficients than those without effusion holes are obtained by installing the effusion holes. With protruding effusion holes, the overall heat/mass transfer characteristics are similar to those with the simple effusion holes. But the Sh values are slightly higher than those of simple effusion holes and the average Sh increases as increasing the length of the protruding effusion holes.
