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On the characteristics of a twin-jet STOVL fountain

Published online by Cambridge University Press:  03 February 2016

A. J. Saddington ,
K. Knowles  and
P. M. Cabrita
A. J. Saddington
Affiliation:
a.j.saddington@cranfield.ac.uk, Aeromechanical Systems Group, Cranfield University, Defence Academy of the UK, Shrivenham, Swindon, UK
K. Knowles
Affiliation:
a.j.saddington@cranfield.ac.uk, Aeromechanical Systems Group, Cranfield University, Defence Academy of the UK, Shrivenham, Swindon, UK
P. M. Cabrita
Affiliation:
a.j.saddington@cranfield.ac.uk, Aeromechanical Systems Group, Cranfield University, Defence Academy of the UK, Shrivenham, Swindon, UK
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Abstract

The interaction of multiple jets with the ground is of great importance for the design and operation of short take-off, vertical landing aircraft. The fountain upwash flow, generated by the impingement of two axisymmetric, compressible, turbulent jets onto a ground plane was studied using laser-based particle image velocimetry and laser Doppler velocimetry. Measurements were made with nozzle pressure ratios of between 1·05 and 4, nozzle height-to-diameter ratios of between 2·4 and 8·4, nozzle splay angles of between ±15 degrees and a nozzle spacing-to-diameter ratio of seven. The effect of varying these parameters on the fountain velocity decay, spreading rate and momentum flux ratio are discussed. Mean fountain upwash velocity profiles were found to be self-similar for all test conditions. A distinct frequency of fountain oscillation was identified but only at a nozzle height of 4·4 diameters.

Type
Research Article
Information
The Aeronautical Journal , Volume 113 , Issue 1140: The International Powered Lift Conference 2008: A Special issue , February 2009 , pp. 139 - 148
Copyright
Copyright © Royal Aeronautical Society 2009 

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