Local Heat Transfer Coefficients in a Rectangular Duct with Plate Blockages of Variable Stream Wise Spacing

An experimental investigation is conducted to determine the effect of repeated-plate blockages of variable streamwise spacing on heat transfer characteristics of turbulent flow in rectangular ducts. The plates are attached to the upper and lower walls in a staggered arrangement. The experiments are carried out by mass transfer and the analogy between heat and mass transfer provides the necessary link between the two processes. The study encompasses both the developing and the periodically fullydeveloped portions of the duct, and the axial distribution of the local transfer coefficients are discussed. The principal variables of the problem are Reynolds number Re, plate height h. and plate streamwise spacing L. The range of Re, h/H (H= duct height), and L/H considered in this study are 3000-50000, 0-0.5, and 1-7. The measurements extended downstream to about 13 duct hydraulic diameter.