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FULL-SCALE TURBOFAN DEMONSTRATION OF A DEPLOYABLE ENGINE AIR-BRAKE FOR DRAG MANAGEMENT APPLICATIONS

[+] Author and Article Information
Parthiv Shah

ATA Engineering, Inc., San Diego, CA, USA
parthiv.shah@ata-e.com

Gordon Pfeiffer

ATA Engineering, Inc., San Diego, CA, USA
gordon.pfeiffer@ata-e.com

Rory Davis

ATA Engineering, Inc., San Diego, CA, USA
rory.davis@ata-e.com

Thomas Hartley

Williams International, Walled Lake, MI, USA
thartley@williams-int.com

Zoltan Spakovszky

Massachusetts Institute of Technology, Cambridge, MA, USA
zolti@mit.edu

1Corresponding author.

ASME doi:10.1115/1.4037155 History: Received February 09, 2017; Revised June 05, 2017

Abstract

This paper presents the design and full-scale ground-test demonstration of an engine air-brake (EAB) nozzle that uses a deployable swirl vane mechanism to switch the operation of a turbofan's exhaust stream from thrust generation to drag generation during approach and/or descent. The EAB generates a swirling outflow in the engine exhaust, creating equivalent drag in the form of fixed-fan speed thrust reduction. Such drag-on-demand enables slower, steeper, and/or aeroacoustically cleaner flight on approach, addressing the need for noise control and access to confined airports. Using NASA's Technology Readiness Level (TRL) definitions, the EAB technology has been matured to a level of 6, through design, fabrication, assembly, and ground-testing of the a deployable mechanism on a Williams International FJ44-4A business jet engine operating at a high approach throttle setting (called dirty approach). The final prototype mechanism satisfied demonstration requirements including (1) equivalent drag equal to 15% of nominal gross thrust, (2) excess nozzle flow capacity and fuel burn reduction when fully deployed , (3) acceptable operability during dynamic deployment and stowing, (4) deployment time of 3-5 seconds, (5) stowing time under 0.5 second, and (6) mechanism packaging within a notional cowl. For a typical twin-jet aircraft application, a constant-speed, steep approach analysis suggests EAB drag could be used without additional airframe drag to increase the glideslope from 3 to 4.3 degrees, with about 3 dB noise reduction at a fixed observer.

Copyright (c) 2017 by ASME
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