The Influence of Rotation on Impingement Cooling

Abstract

The objective of the present work is the experimental investigation of the effects of rotation on the heat transfer due to a single row of circular jets impinging on a curved surface, relevant to turbine blade cooling. The local transfer coefficients were determined by means of the naphthalene sublimation technique using the analogy between heat and mass transfer. Spanwise average transfer coefficients were deduced from the local measurements and are discussed relative to the transfer in a nonrotating system. Results are presented for different stagger angles, jet Reynolds numbers and geometry parameters. The geometry parameters that were varied included the spacing between adjacent jet holes and the distance between the jet hole plate and the impingement surface. It is found that rotation does not improve heat transfer but can reduce it significantly, up to 40% below the transfer coefficient in a nonrotating system. Therefore, the effects of rotation have to be accounted for accurate predictions of the cooling pattern generated by impinging jets.

Recent Studies in Turbine Blade Cooling?

“…The zero staggered of cooling jets (i.e., jet direction is perpendicular to rotation direction) in Figure 18 shows lower heat transfer coefficients compared to that with a staggered angle. Mattern and Hennecke (1996) reported the effect of rotation on the leading edge impingement cooling by using the naphthalene sublimation technique. Their experiment did not include the rotating buoyancy effect.…”

Local heat/mass transfer measurements on effusion plates in impingement/effusion cooling with rotation

“…5(c) shows that the trailing orientation yielded a Sh distribution that was significantly different than that of the other cases. The shifted Sh distributions were presented because the injected jet flow was deflected inward by the Coriolis force [9,15]. High Sh regions with peaks moved inward from the center of the injection hole (at x/d = 6.0, 12.0, and 18.0).…”

“…Epstein et al [8] investigated the heat transfer characteristics of array impingement jets on the leading edges of turbine blades and showed that the rotation effect reduced the cooling performance of the jets. Mattern and Hennecke [9] conducted an experiment using the naphthalene sublimation method and described the local heat/mass transfer distributions as functions of the various parameters, such as hole-to-hole spacing, hole-to-plate spacing, and jet orientation. Regional-average heat transfer characteristics for array jet cooling on flat surfaces were reported by Parsons and Han [10] and Akella and Han [11].…”

Impingement Cooling in Rotating Two-Pass Rectangular Channels with Ribbed Walls

“…These studies [9][10][11][12][13][14] have not addressed the following issues on impingement heat transfer: 1) the effect of angled ribs in nonrotating impingement-cooled blades and 2) the combined effect of rotation and angled ribs in rotating impingement-cooled blades. The compound heat transfer enhancement technique, such as impingement and angled ribs, may provide a better cooling effect for hightemperaturegas turbine blades compared to those with impingement cooling or angled rib cooling alone.…”