Investigation of ribs disturbed entrance effect of heat transfer and pressure drop in pin-fin array

Abstract

Turbine blades are designed to have rather complex internal cooling structures such as ribs and pin-fins, which are installed individually or concurrently in the serpentine channel. In this paper, pin-fin array heat transfer and pressure drop under the ribs induced non-uniform entry condition——entrance effect, have been experimentally investigated using the transient liquid crystals technique. Three configurations respectively installed 60°, V-shaped and W-shaped ribs at the upstream of pin-fin array and a baseline without ribs (representing a uniform entry condition) were tested in the Reynolds number range of 7000–40,000. A numerical simulation was also conducted to obtain more understandings of flow behaviors. The results showed that the entrance effects induced by the three shaped ribs have unique physical characteristics because of the generating of different secondary flow patterns. The entrance effect led to spatially non-uniform heat transfer distributions on pin-fin endwalls, however, its influence was only limited to the upstream region. The entrance effect not only enhanced the overall heat transfer, but also reduced the pressure drop of pin-fin array, hence, resulting in higher thermal efficiency.