For the application of film cooling to turbine blades, experimental investigations were performed on the mixing processes in the near-hole region with a row of holes on the suction suction side of a turbine cascade. Data were obtained using pneumatic probes, pressure tappings, and a three-dimensional subminiature hot-wire probe, as well as surface flow visualization techniques. It was found that at low blowing rates, a cooling jet behaves very much like a normal obstacle and the mixing mainly takes place in the boundary layer. With increasing blowing rates, the jet penetrates deeper into the mainstream. The variation of the turbulence level at the inlet of the turbine cascade and the Reynolds number showed a strong influence on the mixing behavior. The kidney-shaped vortex and as an important achievement the individual horseshoe vortex of each single jet were detected and their exact positions were obtained. This way it was found that the position of the horseshoe vortex is strongly dependent on the blowing rate and this influences the aerodynamic mixing mechanisms. A two-dimensional code for the calculation of boundary layer flows called GRAFTUS was used; however, the comparison with the measurements showed only limited agreement for cascade flow with blowing due to the strong three-dimensional flow pattern.

Issue Section:
Research Papers
Topics:
Cooling, Flow (Dynamics), Jets, Turbine blades, Vortices, Boundary layers, Cascades (Fluid dynamics), Probes, Suction, Turbines, Film cooling, Flow visualization, Kidney, Pressure, Reynolds number, Turbulence, Wire
1.
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2.
Brown, D. B., 1973, “Cold-Air Aerodynamic Study in a Two-Dimensional Cascade of a Turbine Stator Blade With Suction-Surface Film Cooling,” NASA TM X-2685.
3.
Goldstein, B. J., Eckert, E. R. G., and Ito, S., 1987, “Film Cooling in a Plane Turbine Cascade,” Proc. First International Symposium on Transport Phenomena, Honolulu, pp. 37–43.
4.
Haas, W., Rodi, W., and Scho¨nung, B., 1988, “Filmku¨hlung von Turbinen-schaufeln durch Ausblasung aus einer Lochreihe,” ZFW 12, pp. 159–172.
5.
Haller, B. R., 1980, “The Effects of Film Cooling Upon the Aerodynamic Performance of Transonic Turbine Blades,” Ph.D. Thesis, Cambridge.
6.
Jabbari, M. Y., and Goldstein, R. J., 1992, “Vortex Structure and Mass Transfer Near the Base of a Cylinder and a Turbine Blade,” AGARD CP-527 Paper No. 2.
7.
Kiock, R., 1982, “Experimentelle Ermittlung des Grenzschichtumschlags am Turbinengitter T106,” Institut fu¨r Entwurfsaerodynamik, DLR Braunschweig, IB 129-82/3.
8.
Kiock, R., Hoheisel, H., and Dietrichs, H. J., 1985, “The Boundary Layer Behavior of an Advanced Gas Turbine Rotor Blade Under the Influence of Simulated Film Cooling,” AGARD CP-390.
9.
Ko¨llen, O., and Koschel, W., 1985, “Effect of Film Cooling on the Aerodynamic Performance of a Turbine Cascade,” AGARD CP-390, Paper No. 39.
10.
Lo´pez Pe´na, F., and Arts, T., 1992, “On the Development of a Film Cooling Layer,” AGARD CP-527 Paper No. 36.
11.
Manickam, M. D., and Murugesan, K., 1989, “Effect of Discrete Hole Film Cooling on Aerodynamic Performance of a Turbine Cascade,” ISABE 89-7040, Bangalore, pp. 397–404.
12.
McFarland, E. R., 1976, “An Investigation of the Aerodynamic Performance of Film Cooled Turbine Blades,” Ph.D. Thesis, Cincinnati, OH.
13.
Ro¨mer, N., 1990, “Untersuchungen zum Umschlagverhalten der Profilgrenzschicht an Verdichter- und Turbinengittern,” Ph.D. Thesis, UniBw Mu¨nchen, Germany.
14.
Rodi, W., Haas, W., and Scho¨nung, B., 1986, “Untersuchungen des Grenzschichtverhaltens an Turbinenschaufeln unter Beru¨cksichtigung von Filmku¨hlung und von lokalen Ablo¨seblasen,” FVV Forschungsbericht GRAFTUS Heft 310.
15.
Velazquez, M., 1988, “Untersuchungen zur aerodynamischen Simulation der Filmku¨hlung von Gasturbinenschaufeln,” Ph.D. Thesis, Universita¨t Hannover, Germany.
16.
Wilfert, G., Ladwig, M., and Fottner, L., 1990, “PANDA—A New Data Accquisition System for Wake and Profile Pressure Distribution Measurement at the High-Speed Cascade Wind Tunnel,” 10th Symposium on Measuring Techniques for Transonic Flows in Cascades and Turbomachines.
17.
Wunderwald, D., Wilfert, G., and Fottner, L., 1992, “The Experimental Setup of a Triple-Sensor Anemometry and Its Controlling System at the High-Speed Cascade Wind Tunnel,” 11th Symposium on Measuring Techniques for Transonic Flows in Cascades and Turbomachines.
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