DOI: 10.1615/ICHMT.1994.IntSympHetatTransTurb
ISBN Print: 1-56700-016-9
ISBN Print: 978-1-56700-016-0
Local and Average Transfer Coefficients due to Different Impingement Arrangements for Blade Cooling Applications
摘要
The local transfer coefficients which result from the impingement of a single circular jet, a row of circular jets and a square array of circular jets on plane and curved surfaces were determined by means of the naphthalene sublimation technique in conjunction with an efficient data acquisition system. The resolution of this system varies between Δx /dp = 0.1...0.5 ( Δx ≡ distance between two points; dp ≡ jet orifice diameter), resulting in a maximum number of approx. 3 000 measuring points per test. The effects of jet-orifice-plate (insert) to impingement-plate spacing, neighboring jets, jet center-to-center spacing, jet Reynolds number, and the curvature of the configuration were investigated.
The detailed local transfer coefficient distributions enable the identification of locations where effective cooling is provided. It could be shown that the impingement of a jet causes a characteristic transfer coefficient distribution with two maxima locations which is a function of s /dp and Re. Furthermore, local maxima between adjacent jets are observed.
Local transfer coeffcients were averaged numerically to obtain spanwise averaged transfer coefficients. They could be correlated well with Re0.7 and showed good agreement with results from the literature.
For the range of parameters investigated the effect of surface curvature is relatively small.