Detailed Heat Transfer Distributions in Engine Similar Cooling Channels for a Turbine Rotor Blade With Different Rib Orientations

Abstract

Detailed Nusselt number distributions are presented for a gas turbine engine similar internal channel geometry used for cooling a modern first stage rotor blade. The cooling design has one leading edge channel and a three-pass channel that covers the rest of the blade. The simulated model, generated from the midspan section of an actual cooling circuit, was studied for wall heat transfer coefficient measurements using the transient liquid crystal technique. The model wall inner surfaces were sprayed with thermochromic liquid crystals, and a transient test was used to obtain the local heat transfer coefficients from the measured color change. Results are presented for a nominal channel inlet leading edge channel Reynolds number of 10,700 and a channel inlet three-pass channel Reynolds number of 25,500. Detailed heat transfer measurements are presented for the simulated leading edge, first pass, second pass and third pass interior walls for different rib configurations. The channels were studied for smooth, 90 deg ribs, and angled ribs geometries in addition to ribs on the divider walls between adjacent passages. Overall pressure drop measurements were also obtained for each passage. Some of these results are compared with the predicted heat transfer from standard correlations used in design practices. Results show very complicated heat transfer behavior in these realistic channels compared to results obtained in simplistic geometry channels from published studies. In some cases, the Nusselt numbers predicted by correlations are 50–60% higher than obtained from the current experiments.

Heat Transfer Augmentation Technologies for Internal Cooling of Turbine Components of Gas Turbine Engines

“…Recent investigations of rib turbulators address different rib configurations [143][144][145][146][147][148][149][150][151][152][153][154], as well as a variety of other geometric parameters, such as continuous and truncated ribs [155,156], semiattached rib configurations [157], and effects of a turning vane arrangement within a ribbed internal cooling channel [11,149,158]. A variety of internal flow arrangements are addressed, including extraction flow effects and bleed holes [159,160], different crossflow schemes [161], conjugate heat transfer with crossing jets [162], and impingement and effusion cooling with ribbed surfaces [163,164].…”

Conjugate heat transfer analysis of a rotor blade with coolant channels

“…Compared with rectangular or square channels, the realistic coolant channels of a rotor consist of fillets at the corner and have different shapes and sizes. Figure 25A shows the non-dimensionalized geometrical LE channel profile of simplified geometry of Blane et al 20 and realistic rotor channel 1 considered in the present study. As seen from the figure, the simplified geometry does not consist of any fillets, which can bring a major difference in heat transfer trend as presented by the Nusselt number plot in Figure 25B,C.…”

“…They claimed that the study of conjugate heat transfer would provide comprehensive model calibration guidance. Blane et al 20 investigated the heat transfer distribution of a first-stage turbine rotor blade by simplifying the channel geometries. A direct comparison of experimental Nusselt numbers with correlations provided by Han 21 resulted in a Nusselt number difference of 50%-60%.…”

Basic Aspects of Gas Turbine Heat Transfer

“…However, due to the leading edge geometry, the heat transfer is significantly different to that in midchord or trailing edge passages. Several studies show the impact of the turbulator geometry on the overall heat transfer in gas turbine blade leading edges [33,[41][42][43]. In a recent study by Saxer-Felici et al [44], several turbulator geometries were tested at engine representative Reynolds numbers.…”