Design of pre-swirl systems is important for the secondary air cooling system of gas turbine engines. In this paper, three pre-swirl nozzles, a cascade vane and two drilled nozzles are analysed and their performances are compared. The two drilled nozzles considered are a straight drilled nozzle and an aerodynamically designed nozzle. CFD analyses are presented for stand-alone and pre-swirl system 3D sector models at engine operating conditions near to engine maximum power condition rotational Reynolds number (Reφ) up to 4.6 ! 107. Nozzle performance is characterised by the nozzle discharge coefficient (CD), nozzle velocity coefficient (η) and cooling air delivery temperature. Two commonly used eddy viscosity models are employed for the study, the standard k-ε and Spalart-Allmaras models with wall functions. Both models give very similar results for CD and η, and are in reasonable agreement with available experimental data. Effects of nozzle or vane number and sealing flow have been analysed. The cascade vanes perform slightly better than the aerodynamically designed drilled nozzles but the final design choice will depend on other component and manufacturing costs. An elementary model is presented to separate temperature losses due to the nozzle, stator drag and sealing flow.

Volume Subject Area:
Heat Transfer
Topics:
Cascades (Fluid dynamics), Nozzles, Design, Engines, Flow (Dynamics), Sealing (Process), Temperature, Computational fluid dynamics, Cooling, Cooling systems, Discharge coefficient, Drag (Fluid dynamics), Eddies (Fluid dynamics), Gas turbines, Manufacturing, Reynolds number, Stators, Viscosity
This content is only available via PDF.
Copyright © 2011
 by Rolls-Royce plc
You do not currently have access to this content.