Effect of Rotation on Detailed Heat Transfer Distribution for Various Rib Geometries in Developing Channel Flow

Abstract

The effects of CorioHs force and centrifugal buoyancy have a significant impact on heat transfer behavior inside rotating internal serpentine coolant channels for turbine blades. Due to the complexity of added rotation inside such channels, detailed knowledge of the heat transfer will greatly enhance the blade designer's abiiity to predict hot spots so coolant may be distributed more effectively. The effects of high rotation numbers are investigated on the heat transfer distributions for different rib types in near entrance and entrance region of the channels. It is important to determine the actuai enhancement derived from turbulating channel entrances where heat transfer is already high due to entrance effects and boundary layer growth. A transient liquid crystal technique is used to measure detailed heat transfer coefficients (htc)for a rotating, short length, radially outward coolant channel with rib turbuiators. Different rib types such as 90 deg, W, and M-shaped ribs are used to roughen the walls to enhance heat transfer. The channel Reynolds number is held constant at 12,000 while the rotation number is increased up to 0.5. Results show that in the near entrance region, the high performance W and M-shaped ribs are just as effective as the simple 90 deg ribs in enhancing heat transfer. The entrance effect in the developing region causes significantiy high baseline heat transfer coefficients thus reducing the effective of the ribs to further enhance heat transfer. Rotation causes increase in heat transfer on the trailing side, while the leading side remains relatively constant limiting the decrement in leading side heat transfer. For all rotational cases, the W and M-shaped ribs show significant effect of rotation with large differences between leading and trailing side heat transfer.

Thermal Performance of V-Shaped and X-Shaped Ribs in Trapezoidal Cooling Channels

“…A numerical investigation found that W-shaped ribs increased heat transfer enhancement at the cost of higher pressure drop and the optimal pitch-to-rib height ratio was 10 [17]. In addition, the M-shaped and W-shaped ribs were also useful for enhancing heat transfer in the entrance region of a rotating cooling channel [18]. However, the thermal hydraulic performance of the W-shaped and M-shaped ribs could be inferior to that of the V-shaped ribs [19].…”

Effect of topology on hybrid-linked jet impingement

“…Investigations combining the effect of target surface conditions and rotation can be found in Elston and Wright [15,16], Hong et al [17][18][19]. and Lamont et al [20][21][22].…”