General Electric, Allison, Air Force

• Computations of Inverse Phase Change Using a New Enthalpy Method - Numerical Methods in Thermal Problems, Vol. IX, Part 2
• A Numerical Study of Discrete Hole Film Cooling - ASME Paper, 96-WA/HT/-8, Atlanta, GA
• Computation of Discrete Hole Film Cooling: Hydrodynamic Study - ASME Paper, 97-GT-80, Orlando, FL
• A Numerical Study of Discrete-Hole Film Cooling - Submitted to Numerical Heat Transfer, February 1998
• Curvature Effects on Discrete-Hole Film Cooling - Presented at the 1998 ASME Turbo Expo in Stockholm, Sweden, June 1998
• Investigation of Discrete-Hole Film Cooling Parameters Using Curved-Plate Models - Presented at the 1998 ASME Turbo Expo in Stockholm, Sweden, June 1998
• Measurements in Film Cooling Flows: Hole L/D and Turbulence Intensity Effects - ASME Paper 96-WA/HT/7, To Be Published in Trans ASME Journal of Turbomachinery
• Measurements of Aerodynamics Penalties Associated with Film Cooling - Submitted to 1998 ASME IMECE, Anaheim, CA
• Influence of Coolant Supply Plenum Geometry on Film Coolant Surface Adiabatic Effectiveness - ASME Paper 97-GT-25
• Measurements of Discharge Coefficients in Film Cooling - Accepted to 1998 ASME IGTC/ Turbo Expo, Stockholm, Sweden, and Recommended for Publication in ASME Transactions J. Turbomachinery-ASME Paper 98-GT-009
• Turbulence Spectra and Length Scales Measured in Film Coolant Flows Emerging from Discrete Holes - Accepted to 1998 ASME IGTC/Turbo Expo, Stockholm, Sweden, and Recommended for Publication in ASME Transactions J. Turbomachinery
• Total-Coverage Discrete Hole Wall Cooling - Journal of Turbomachinery, Vol. 119, No. 2, Pp. 329-338, 1997
• Experimental Mass (Heat) Transfer in and Near a Circular Hole in a Flat Plate - International Journal of Heat and Mass Transfer, Vol. 40, Pp. 2431-2441, 1997
• Exploration of the Influence of Heat Conduction on Temperature Distribution in Turbine Blades - HTD-Vol. 350, National Heat Transfer Conference, Vol. 12
• Heat (Mass) Transfer and Film Cooling Effectiveness With Injection Through Discrete Holes, Part I: Within Holes and on the Back Surface - Journal of Turbomachinery, Vol. 117, Pp.440-450, 1995
• Heat (Mass) Transfer and Film Cooling Effectiveness With Injection Through Discrete Holes, Part II: On Exposed Surface - Journal of Turbomachinery, Vol. 117, Pp. 451-460, 1995
• The Influence of Secondary Flows Near the Endwall and Boundary Layer Disturbance on Convective Transport From a Turbine Blade - Journal of Turbomachinery, Vol. 117, Pp. 675-665, 1995
• Effect of Plenum Cross-Flow on Heat (Mass) Transfer Near and Within the Entrance of Film Cooling Holes - Journal of Turbomachinery, Vol. 119, No. 4 Pp. 761-769, 1997
• Row-of-Holes Film Cooling of a Convex and a Concave Wall at Low Injection Angles - Journal of Turbomachinery Vol. 119 No.3, Pp. 574-579, 1997
• Film Cooling Effectiveness and Mass/Heat Transfer Coefficient Downstream of One Row of Discrete Holes - Presented at the 43rd ASME Gas Turbine and Aeroengine Congress, Stockholm, Sweden, June 2-5, 1998. Recommended for Publication in the Journal of Turbomachinery, ASME Paper 98-GT-174
• Effects of Blade Profile on Turbine Blade Heat (Mass) Transfer - Symposium on Process, Enhanced and Multiphase Heat Transfer in Honor of Professor Author E. Bergles, Georgia Institute of Technology, Atlanta, Georgia, November 16, 1996
• Influence of High Free Stream Turbulence on Mass/Heat Transfer in a Simulated High Performance Turbine Blade Cascade - Accepted for Presentation at the XVI UIT National Heat Transfer Conference, Siena, Italy, June 17-19, 1998
• Film Cooling of Gas Turbine Endwall With Discrete-Hole Injection - Journal of Turbomachinery, Vol. 118, Pp. 278-284, 1996
• Flow Measurements in Film Cooling Flows With Lateral Injection - Presented at the 1998 ASME Turbo Expo in Stockholm, Sweden, June 1998, ASME Paper 98-GT-054
• Film Cooling of Gas Turbine Endwall With Discrete-Hole Injection - Journal of Turbomachinery, Vol. 118, Pp. 278-284, 1996
• Measurements in Film Cooling With Lateral Injection: Adiabatic Effectiveness Values and Temperature Fields - Submitted to the 1998 ASME IMECE Conference, Anaheim, CA , November 1998
• A Study of Film Cooling Injection Geometry's: Measured Flow and Thermal Fields With Lateral, Compound, and In-Line Injection - Submitted to the 1998 ASME IMECE Conference, Anaheim, CA , November 1998
• Flow and Heat Transfer Measurements in Gas Turbine Film Cooling - Presented at the Energy Sources Technology Conference and Exhibition, 1998
• In Search of a Blowing Parameter for Correlating Film Cooling Effectiveness Data - 2nd European Thermal Sciences and 14th UIT National Heat Transfer Conference, Rome, Italy, Pp. 647-653, May 1996
• Effect Endwall Boundary Conditions on Turbine Blade Mass Transfer in Presence of High Freestream Turbulence - Accepted for Presentation at the 11th International Heat Transfer Conference, Seoul, Korea, August 23-28, 1998
• Effect of High Free Stream Turbulence with Large Length Scale on Blade Heat/Mass Transfer - Presented at the 43rd ASME Gas Turbine and Aeroengine Congress, Stockholm, Sweden, June 2-5 1998, Recommended for Publication in the Journal of Turbomachinery, ASME Paper 98-GT-107
• Secondary Flows in the Blade/Endwall Region of a Turbine Cascade - Symposium on Thermal Science and Engineering in Honor of Chancellor Chang-Lin Tie, University of California, Berkeley, California, November 14, 1995
• Flow Visualization in a Linear Cascade of High Performance Turbine Blades - Journal of Turbomachinery, Vol. 119, No. 1 Pp. 1-8, 1997
• Measurements of Mean Flow and Eddy Transport Over a Film Cooling Surface - HTD-Vol. 327, National Heat Transfer Conference, Vol. 5.
• Film Cooling Effectivness and Mass/Heat Transfer Coefficinte Downstream of a Row of Holes with Compound Angle Injection - Submitted to the 44th ASME Gas Turbine and Aeroengine Congress, Indianapolis, Indiana, June 1999
• Effect of Wake-Distributed Flow on Heat (Mass) Transfer to a Turbine Blade - Submitted to the 44th ASME Gas Turbine and Aeroengine Congress, Indianapolis, Indiana, June 1999
• Effect of Edge Roughness on the Development of Taylor-Gortler Vortices on Pressure Surface of a Turbine Blade - Submitted to Experiments of Fluids
• Mass Transfer From a Simulated Gas Turbine Blade in the Pressence of Taylor- Gortler Vortices - Submitted to International Journal of Heat and Mass Transfer
• A Numerical Study of Discrete-Hole Film Cooling - Thesis, University of Minnesota , MN
• Experiments in Film With Various Coolant Delivery Geometries - Master of Science Thesis in Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, December 1996
• Film Cooling Effectiveness and Mass/Heat Transfer Coefficients Downstream of One Row of Discrete Holes With 45 Degree Compound Angle - Master of Science Thesis in Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, March 1998
• Measurements in Film Cooling Flows With Lateral Injection - Master of Science Thesis in Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, January 1998
• Prediction of Three-Dimensional Film Cooling Situations - Ph.D. Dissertation, University of Minnesota, Minneapolis, Minnesota, June 1997
• Film Cooling Effectiveness and Heat (Mass) Transfer Coefficient for a Single Row of Discrete Film Cooling Holes - Master of Science Thesis in Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, May 1996
• Effects of High Turbulence and Wakes on Heat (Mass) Transfer from Gas Turbine Blades - Ph.D. Dissertation, University of Minnesota, Minneapolis, Minnesota , June 1998
• Local Mass Transfer Measurement From a Turbine Blade: Influence of High Turbulence With Large Length Scale on Heat/Mass Transfer - Ph.D. Dissertation, University of Minnesota, Minneapolis, Minnesota, October 1997

Performing Member Contact:

Dr. R. J. Goldstein, Prof., Head/ME

University of Minnesota
Department of Mechanical Engineering
125 Mechanical Engineering
111 Church Street, S.E.
Minneapolis, MN 55455-0111
612-625-5552/FAX 612-625-3434
rjg@me.umn.edu

• Fluid mechanics, HT

• HT, Flow fields, Film cooling

• New cascade/wind tunnel to be used for flow visualization/mass transfer studies

University of Minnesota

A new wind tunnel and cascade has been constructed and installed. It provides access for flow visualization from all sides, enabling recording of the flow structure. The new setup can accommodate turbulence generating grids, a combustor simulator, a wake producing row of airfoils, and shroud-tip clearances with a stationary or moving shroud. A flow visualization study is under way. Preliminary results confirm the vortex flow model deduced on the basis of earlier measurements and visualizations. Investigation at high free-stream turbulence, periodic impinging wakes, and tip leakage flows are planned.

Measurements of heat transfer within and around film cooling holes are underway. The coefficients inside the hole with crossflow are similar to those without crossflow, except at very low boiling rates. Therefore, data from a simple, short-hole flow can be applied in general.

Local film cooling effectiveness values have been measured using pure air injection and saturated naphthalene-and-air-mixture injection. This allows detailed effectiveness measurements of the entire domain (including near the injection holes). For an inline array of injection holes, the local effectiveness values vary by a factor of two from the average in the lateral direction.

A study on film cooling from a row of holes on convex and concave surfaces with injection at 15, 25, and 45 degrees to the mainstream has been completed. At low blowing rates, the injection angle is not important; as the blowing rate is increased, lower injection angles are preferred because the jets remain close to the wall; at high blowing rates the vortices form neighboring jets interact such that more coolant reaches the surface from steeper jets than from shallower jets. Wall curvature and density ratio effects on this behavior have been obtained.

An investigation of mass transfer from stepped pin fin arrays, for internal blade cooling passages, has been completed. Several fin shapes and arrangements were investigated. The results show increased average mass transfer and reduced pressure drop when compared to straight cylindrical pin fins. Flow visualization and measurements of local mass transfer, heat transfer, and flow velocity are being conducted.

Recently, an investigation of boundary layer behavior on a concave wall and a downstream flat wall was conducted. When the free-stream turbulence level was high, no cellular level was high, no cellular activity of the Gortler type was observed on the concave wall, but turbulence transport and wall skin friction and heat transfer were enhanced by curvature. Similar to the low-turbulence cases, recovery to flat-wall behavior was slow. The tendency for the large-scale eddies in the boundary layer flow to lift off the recovery wall, observed in the low-turbulence case, still existed, but was somewhat diminished by the elevated core turbulence.

Experiments have been conducted on airfoil surfaces that simulate modern gas turbine blades with respect to geometry, flow acceleration, curvature, core turbulence, and chord Reynolds number but do not simulate compressibility effects. Core turbulence decays from 10% to 3% due to the strong acceleration. Regions influenced by the airfoil surface are much thicker than predicted by the k - e boundary layer codes with acceleration and free-stream turbulence levels properly modeled. The discrepancy may lie with the inability of the k - e model to capture large eddy structure effects. Measurements show a cross-transport of momentum from the convex surface toward the concave surface in both pressure-surface and suction-surface boundary layers. This, also, cannot be captured by k - e modeling.

The combined effects of strong (K=5x10 -6 ) acceleration, concave curvature and high (8%) free-stream turbulence level on boundary layer transition has been documented experimentally. Moderate (K=0.75x10 -6 ) acceleration was shown to have little on transition at this free-stream turbulence level, but at the higher acceleration, the transition zone is significantly lengthened. Within transition, the non-turbulent portion of the flow is highly disturbed and does not appear laminar-like. Streamwise velocity fluctuations in the non-turbulent zones are nearly as high as in the turbulent zone. The hydrodynamic and thermal laws of the wall have been examined for accelerating flow, and new formulations have been developed which agree well with experimental data. These hydrodynamic and thermal laws are useful for extracting skin friction coefficients and turbulent Prandtl numbers on the concave wall.

Film cooling calculations show that parabolic techniques give accurate effectiveness predictions in regions sufficiently far downstream of the injection holes. An anisotropic turbulence model enhances the prediction. A turbulence model which accurately accounts for the nonequilibrium nature of the jet and boundary layer interaction is expected to further enhance this prediction. Laterally-averaged effectiveness is found to be of secondary importance to wall curvature, density ration, and blowing rate. Lateral profiles are strong functions of injection angle. Low injection angles yield somewhat higher film cooling effectiveness values at moderate blowing rates while steeper jets can yield higher laterally-averaged effectiveness values at higher blowing rates. This reversal is related to differences in lateral spreading rates and lift-off and touchdown of the injected fluid.