Flow and heat transfer behaviors of double-passages ribbed U channel under varied rotating conditions and rib structures

Increasing turbine inlet temperature in gas turbines due to the demand for improved thermal efficiency brings a challenge for blade temperature tolerance. Hence, it is crucial to develop and investigate a high-efficiency blade cooling structure. In the study, a double-passage reversed V ribbed U channel is investigated for thermal and flow characteristics under Re of 16 000 and Ro in the range of −0.024–0.2 by experimental transient liquid crystal approach and numerical Reynolds-averaged Navier–Stokes method. The key configuration of the double-passages U-channel is to arrange a partition between the suction surface and the pressure surface of the traditional channel, forming a U bend region at the top area. The result reveals that the channel possesses the merit of superior heat transfer ability and low pressure drop under rotating state, whose Nusselt number ratio at Ro of 0.006, 0.024, and 0.2 has an ascending trend with 1.75, 1.91, and 2.21, respectively. In addition, the interactions among the Coriolis force, various rib structures, and the bend of the channel are explored by comparing the reversed V rib with the 45° rib and the V rib in three double-passage ribbed U channels. With identical pumping power, all three channels gain heat transfer improvement when Ro is rising, manifesting that the double-passage ribbed U channel is promising for rotating blade cooling.