22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-2.9.1

COMPARISON OF JET INDUCED LIFT LOSS FOR SINGLE AND COAXIAL JETS

A. J. Saddington, K. Knowles
Cranfield University, UK

Keywords: jet, co-annular, stovl, suckdown

A series of experiments has been conducted to measure the suckdown force induced on a circular flat baffle plate by a co-annular jet operating in ground effect. A range of nozzle pressure ratio (NPR) and height combinations was investigated. Total pressure measurements were also made using a Pitot probe traversed radially through the centre of the jet and along the jet axis. Total pressure traverses through the jet centre indicated that the co-annular jet had reasonably good axi-symmetry. The data agreed quite well with previous experimental observations regarding decay rates and core acceleration in some inverted-profile cases. With a subsonic core flow, suckdown force measurements in ground effect were largely independent of NPR. With a supersonic core flow, the results indicated that a normal profile co-annular jet gave a lower percentage suckdown at nozzle heights h D < 5 . All the data showed good correlation with previous experiments.

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