Adiabatic Wall Effectiveness Measurements of Film-Cooling Holes With Expanded Exits
Tóm tắt
This paper presents detailed measurements of the film-cooling effectiveness for three single, scaled-up film-cooling hole geometries. The hole geometries investigated include a cylindrical hole and two holes with a diffuser-shaped exit portion (i.e., a fan-shaped and a laid-back fan-shaped hole). The flow conditions considered are the crossflow Mach number at the hole entrance side (up to 0.6), the crossflow Mach number at the hole exit side (up to 1.2), and the blowing ratio (up to 2). The coolant-to-mainflow temperature ratio is kept constant at 0.54. The measurements are performed by means of an infrared camera system, which provides a two-dimensional distribution of the film-cooling effectiveness in the near field of the cooling hole down to x/D = 10. As compared to the cylindrical hole, both expanded holes show significantly improved thermal protection of the surface downstream of the ejection location, particularly at high blowing ratios. The laidback fan-shaped hole provides a better lateral spreading of the ejected coolant than the fan-shaped hole, which leads to higher laterally averaged film-cooling effectiveness. Coolant passage cross-flow Mach number and orientation strongly affect the flowfield of the jet being ejected from the hole and, therefore, have an important impact on film-cooling performance.
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Tài liệu tham khảo
Giebert, D., M. Gritsch, A. Schulz, and S. Wittig, 1997, “Film-Cooling From Holes With Expanded Exits: A Comparison of Computational Results With Experiment,” ASME Paper No. 97-GT-163.
Goldstein R. , EckertE., and BurggrafF., 1974, “Effects of Hole Geometry and Density on Three-Dimensional Film Cooling,” Int. J. Heat Mass Transfer, Vol. 17, pp. 595–607.
Gritsch M. , SchulzA., and WittigS., 1998, “Discharge Coefficient Measurements of Film-Cooling Holes With Expanded Exits,” ASME JOURNAL OF TURBOMACHINERY, Vol. 120, this issue, pp. 557–563.
Haller B. , and CamusJ., 1984, “Aerodynamic Loss Penalty Produced by Film Cooling Transonic Turbine Blades,” ASME Journal of Engineering for Gas Turbines and Power, Vol. 106, pp. 198–205.
Hay N. , LampardD., and BenmansourS., 1983, “Effect of Crossflows on the Discharge Coefficient of Film Cooling Holes,” ASME Journal of Engineering for Power, Vol. 105, pp. 243–248.
Hay, N., and D. Lampard, 1995, “The Discharge Coefficient of Flared Film Cooling Holes,” ASME Paper No. 95-GT-15.
Liess C. , 1975, “Experimental Investigation of Film Cooling With Ejection From a Row of Holes for the Application to Gas Turbine Blades,” ASME Journal of Engineering for Power, Vol. 97, pp. 21–27.
Makki, Y., and G. Jakubowski, 1986, “An Experimental Study of Film Cooling From Diffused Trapezoidal Shaped Holes,” AIAA Paper No. 86-1326.
Martiny, M., R. Schiele, M. Gritsch, A. Schulz, and S. Wittig, 1996, “In Situ Calibration for Quantitative Infrared Thermography,” in: QIRT’96 Eurotherm Seminar No. 50, Stuttgart, Germany, Sept. 2-5.
Schmidt D. , SenB., and BogardD., 1996a, “Film Cooling With Compound Angle Holes: Adiabatic Effectiveness,” ASME JOURNAL OF TURBOMACHINERY, Vol. 118, pp. 807–813.
Schmidt, D., B. Sen, and D. Bogard, 1996b, “Effect of Surface Roughness on Film Cooling,” ASME Paper No. 96-GT-299.
Sen B. , SchmidtD., and BogardD., 1996, “Film Cooling With Compound Angle Holes: Heat Transfer,” ASME JOURNAL OF TURBOMACHINERY, Vol. 118, pp. 800–806.
Sinha A. , BogardD., and CrawfordM., 1991, “Film Cooling Effectiveness Downstream of a Single Row of Holes With Variable Density Ratio,” ASME JOURNAL OF TURBOMACHINERY, Vol. 113, pp. 442–449.
Spaid F. , and ZukoskiE., 1968, “A Study of the Interaction of Gaseous Jets From Transverse Slots With Supersonic External Flows,” AIAA Journal, Vol. 6, pp. 205–212.
Thole K. , GritschM., SchulzA., and WittigS., 1997, “Effect of a Crossflow at the Entrance to a Film-Cooling Hole,” ASME Journal of Fluids Engineering, Vol. 119, pp. 533–540.
Thole K. , GritschM., SchulzA., and WittigS., 1998, “Flowfield Measurements for Film-Cooling Holes With Expanded Exits,” ASME JOURNAL OF TURBOMACHINERY, Vol. 120, pp. 327–336.