Discharge Coefficient Measurements of Film-Cooling Holes With Expanded Exits

This paper presents the discharge coefficients of three film-cooling hole geometries tested over a wide range of flow conditions. The hole geometries include a cylindrical hole and two holes with a diffuser-shaped exit portion (i.e., a fan-shaped and a laidback fan-shaped hole). The flow conditions considered were 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 pressure ratio across the hole (up to 2). The results show that the discharge coefficient for all geometries tested strongly depends on the flow conditions (crossflows at hole inlet and exit, and pressure ratio). The discharge coefficient of both expanded holes was found to be higher than of the cylindrical hole, particularly at low pressure ratios and with a hole entrance side crossflow applied. The effect of the additional layback on the discharge coefficient is negligible.

[1]  Y. Makki,et al.  An experimental study of film cooling from diffused trapezoidal shaped holes , 1986 .

[2]  D. Lampard,et al.  Discharge Coefficient of Turbine Cooling Holes: A Review , 1998 .

[3]  D. Lampard,et al.  The Coefficient of Discharge of 30° Inclined Film Cooling Holes With Rounded Entries or Exits , 1994 .

[4]  Achmed Schulz,et al.  Film-Cooling From Holes With Expanded Exits: A Comparison of Computational Results With Experiments , 1997 .

[5]  B. R. Haller,et al.  Aerodynamic Loss Penalty Produced by Film Cooling Transonic Turbine Blades , 1984 .

[6]  David G. Bogard,et al.  Film Cooling With Compound Angle Holes: Heat Transfer , 1994 .

[7]  D. Lampard,et al.  The Discharge Coefficient of Flared Film Cooling Holes , 1995 .

[8]  Achmed Schulz,et al.  Flowfield Measurements for Film-Cooling Holes With Expanded Exits , 1998 .

[9]  Achmed Schulz,et al.  Effect of a Crossflow at the Entrance to a Film-Cooling Hole , 1997 .

[10]  S. J. Kline,et al.  Describing Uncertainties in Single-Sample Experiments , 1953 .

[11]  E. Markland,et al.  Discharge Coefficients for Incompressible Non-Cavitating Flow through Long Orifices , 1965 .

[12]  N. Hay,et al.  Discharge Coefficients of Holes Angled to the Flow Direction , 1994 .

[13]  R. J. Goldstein,et al.  Effects of hole geometry and density on three-dimensional film cooling , 1974 .

[14]  Achmed Schulz,et al.  TRANSONIC FILM-COOLING INVESTIGATIONS:EFFECTS OF HOLE SHAPES AND ORIENTATIONS , 1996 .

[15]  The compressible discharge of air through small thick plate orifices , 1964 .

[16]  D. Lampard,et al.  Effect of Crossflows on the Discharge Coefficient of Film Cooling Holes , 1983 .

[17]  David G. Bogard,et al.  Film Cooling With Compound Angle Holes: Adiabatic Effectiveness , 1994 .

[18]  Achmed Schulz,et al.  Adiabatic Wall Effectiveness Measurements of Film-Cooling Holes With Expanded Exits , 1997 .