The effects of atmospheric turbulence on fuel consumption in extended formation flight

Extended formation flight (streamwise separations of between 10 to 40 spans), has been recently proposed as a method for reducing the induced drag of commercial aircraft. However, induced drag savings are not necessarily directly indicative of fuel savings. In a realistic environment, atmospheric turbulence will continuously perturb the formation’s aircraft and their wakes. As a result, each aircraft in the formation will experience fluctuations in aerodynamic loads. For an aircraft to maintain accurately its position within a formation, it must continually adjust its throttle setting. This dynamic throttling may result in inefficient engine operation, thereby detracting from the reductions in induced drag. In this work, a high-fidelity transient engine model, representative of a typical commercial high-bypass turbofan engine, has been incorporated within a simple twin-aircraft formation flight simulator. The aerodynamic interactions between aircraft were modelled using a horseshoe vortex method, specially adapted for extended formations. The aircraft were constrained to longitudinal motion, with altitude fixed. This created a two degree of freedom formation model that is analogous to wind tunnel experimentation. A simple proportional gain controller was used to manipulate the throttle settings, in an attempt to maintain the trail aircraft’s position relative to the leader, in a turbulent atmosphere. It was found that a fuel saving of approximately 25 may be achieved at a practical lateral separation of 1 span, corresponding to a stream-wise separation of 20 ± 0.3 spans, in moderate turbulence levels.

Grantor dc:publisher.institution

Department of Mechanical Engineering

Year dc:date.issued

2014

Author dc:creator

• Sanders, Drewan S

Advisor dc:contributor.advisor

• Redelinghuys, Christiaan

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/9147

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/9147