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The Application of a Lifting-Surface Method to Large, Steady or Oscillating Models in Subsonic, Closed, Open or Slotted Wind Tunnels

Published online by Cambridge University Press:  07 June 2016

R A Streather
R A Streather*
Affiliation:
Aeronautics Research Unit, CSIR, Pretoria, formerly University of Natal, Durban
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Summary

A subsonic, lifting-surface method is extended to apply to low-frequency oscillations of wind-tunnel models, taking into account both longitudinal and lateral variations of tunnel lift interference. Rectangular sectioned tunnels with closed, slotted or open roof and floor and closed sidewalls are considered. A comparison is made between the aerodynamic derivatives obtained by this method and those calculated with the assumption that the model span is small compared to the tunnel width. Three models of aspect ratio 2.67 and different sweepback are considered in rigid pitching oscillations in tunnels of width/height ratio 2.5. The greatest differences between the results from the two methods occur for the tunnel with closed roof and floor and for the unswept planform. The least differences occur for the slotted tunnel and for the planform of greatest sweepback. The results indicate that, for models of conventional size [up to span/(tunnel width) ratio of 0.4], the “small-span” assumption is satisfactory in tunnels with slotted roof and floor and closed side walls, but not in fully closed tunnels.

Type
Research Article
Information
Aeronautical Quarterly , Volume 26 , Issue 1 , February 1975 , pp. 41 - 55
Copyright
Copyright © Royal Aeronautical Society. 1975

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References

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