Experimental study on heat transfer improvement structures with staggered transverse elongated pedestal array

摘要

Experiments have been conducted to investigate the overall thermal performance of a rectangular channel implemented with an elongated pedestal array. The staggered pedestals were elongated transversely (perpendicular to flow direction) in order that the jet flow from between the pedestals impinges at the center of the pedestals in downstream row. The average heat transfer of the pedestal and endwall surfaces were measured by the lumped capacitance method and transient liquid crystal method, respectively. The pressure drop across the pedestal arrays was measured. The heat transfer coefficients were measured over the Reynolds number range from 6000 to 25,000. Four test sections were designed to evaluate the effect of geometric parameters, i.e. major axis to minor axis ratio D/d = 5.0 and 8.0, X/d = 0.8-1.2, S/d =1.175-1.5. Conclusions were drawn as the elongated pedestal array provided considerably high heat transfer enhancement. However, the overall thermal performance was compromised by a very high pressure drop across the pedestal array.