Page 291 - Fluid Mechanics and Thermodynamics of Turbomachinery

272 Fluid Mechanics, Thermodynamics of Turbomachinery

FIG. 8.19. Cross section of film-cooled radial turbine.

where T m is the rotor metal temperature,

2
1
T 0 D U /C p , is half the drop in stagnation temperature of the
2 2
gas as a result of doing work on the rotor,
T 0c is the stagnation temperature of the cooling air.

Rodgers refers to tests which indicate the possibility of obtaining ε D 0.30 at the
rotor tip section with a cooling flow of approximately 10% of the main gas flow.
Since the cool and hot streams rapidly mix, effectiveness decreases with distance
from the point of impingement. A model study of the heat transfer aspects of
film-cooled radial flow gas turbines is given by Metzger and Mitchell (1966).

References

Abidat, M., Chen, H., Baines, N. C. and Firth, M. R. (1992). Design of a highly loaded
mixed flow turbine. J. Power and Energy, Proc. Instn. Mech. Engrs., 206,95 107.
Anon. (1971). Conceptual design study of a nuclear Brayton turboalternator-compressor.
Contractor Report, General Electric Company. NASA CR-113925.
Balje, O. E. (1981). Turbomachines A guide to Design, Selection and Theory. Wiley.
Benson, R. S. (1970). A review of methods for assessing loss coefficients in radial gas
turbines. Int. J. Mech. Sci., 12.
Benson, R. S., Cartwright, W. G. and Das, S. K. (1968). An investigation of the losses in
the rotor of a radial flow gas turbine at zero incidence under conditions of steady flow.
Proc. Instn. Mech. Engrs. London, 182,Pt3H.
Bridle, E. A. and Boulter, R. A. (1968). A simple theory for the prediction of losses in rotors
of inward radial flow turbines. Proc. Instn. Mech. Engrs. London, 182,Pt3H.
Fullagar, K. P. L. (1973). The design of air cooled turbine rotor blades. Symposium on Design
and Calculation of Constructions Subject to High Temperature, University of Delft.
Futral, M. J. and Wasserbauer, C. A. (1965). Off-design performance prediction with exper-
imental verification for a radial-inflow turbine. NASA TN D-2621.
Glassman, A. J. (1976). Computer program for design and analysis of radial inflow turbines.
NASA TN 8164.
Hiett, G. F. and Johnson, I. H. (1964). Experiments concerning the aerodynamic performance
of inward radial flow turbines. Proc. Instn. Mech. Engrs. 178,Pt3I.
Horlock, J. H. (1966). Axial Flow Turbines. Butterworths. (1973 reprint with corrections,
Huntington, New York: Krieger.)
Huntsman, I., Hodson, H. P. and Hill, S. H. (1992). The design and testing of a radial flow
turbine for aerodynamic research. J. Turbomachinery, Trans. Am. Soc. Mech. Engrs., 114,4.