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Loss and Deviation in Windmilling Fans

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Publication Date: 2016-03-25

Journal Title: Journal of Turbomachinery

Publisher: ASME

Volume: 138

Issue: 10

Number: 101002

Language: English

Type: Article

This Version: AM

Metadata: Show full item record

Citation: Gunn, E. J., & Hall, C. A. (2016). Loss and Deviation in Windmilling Fans. Journal of Turbomachinery, 138 (10. 101002)https://doi.org/10.1115/1.4033163

Description: This is the author accepted manuscript. The final version is available from ASME via http://dx.doi.org/10.1115/1.4033163

Abstract: For an unpowered turbofan in flight the airflow through the engine causes the fan to freewheel. This paper considers the flow-field through a fan operating in this mode, with emphasis on the effects of blade row losses and deviation. A control volume analysis is used to show that windmilling fans operate at a fixed flow coefficient which depends on the blade metal and deviation angles, while the blade row losses are shown to determine the fan mass flow rate. Experimental and numerical results are used to understand how the loss and deviation differ from the design condition due to the flow physics encountered at windmill. Results are presented from an experimental study of a windmilling low-speed rig fan, including detailed area traverses downstream of the rotor and stator. 3D CFD calculations of the fan rig and a representative transonic fan windmilling at a cruise flight condition have also been completed. The rig test results confirm that in the windmilling condition the flow through the fan stator separates from the pressure surface over most of the span. This gene-rates high loss and the resulting blockage changes the rotor work profile leading to modified rotational speed. In the engine fan rotor, a vortex forms at the pressure surface near the tip and further loss results from a hub separation caused by blockage from the downstream core and splitter.

Keywords: turbochargers, fans, flow (dynamics), rotors, blades, stators, flight, pressure, engines, air flow

Sponsorship: EPSRC


External DOI: https://doi.org/10.1115/1.4033163

This record's URL: https://www.repository.cam.ac.uk/handle/1810/254948

Autor: Gunn, Ewan J.Hall, Cesare A.

Fuente: https://www.repository.cam.ac.uk/handle/1810/254948


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