In high-efficiency gas turbine engines, the cooling air for the high-pressure turbine stage is expanded through stationary preswirl nozzles, transferred through the preswirl chamber, and delivered to the blade feed holes of the rotor. By accelerating the cooling air in the direction of rotation, the total temperature relative to the rotor disk and the pressure losses occurring at the receiver hole inlet can be reduced. The discharge behavior of a direct-transfer preswirl system has been investigated experimentally for different number of receiver holes and different inlet geometries, varying axial gap widths between stator and rotor and for rotational Reynolds numbers up to The discharge coefficients of the preswirl nozzles are given in the absolute frame of reference while the definition of the discharge coefficients of the receiver holes is applied to the rotating system in order to consider the work done by the rotor. A momentum balance is used to evaluate the deflection of the preswirled air entering the receiver holes. The flow in the preswirl chamber is characterized by introducing an effective velocity of the cooling air upstream of the rotor disk. The influences of geometrical parameters and operating points are reported and discussed in this paper.
Direct-Transfer Preswirl System: A One-Dimensional Modular Characterization of the Flow
Contributed by the International Gas Turbine Institute (IGTI) of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS for publication in the ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Paper presented at the International Gas Turbine and Aeroengine Congress and Exhibition, Atlanta, GA, June 16–19, 2003, Paper No. 2003-GT-38312. Manuscript received by IGTI, Oct. 2002, final revision, Mar. 2003. Associate Editor: H. R. Simmons.
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Dittmann, M., Dullenkopf , K., and Wittig, S. (April 15, 2005). "Direct-Transfer Preswirl System: A One-Dimensional Modular Characterization of the Flow ." ASME. J. Eng. Gas Turbines Power. April 2005; 127(2): 383–388. https://doi.org/10.1115/1.1787514
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