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The Effect of Sting Supports on the Base Pressure of a Blunt-Based Body in a Supersonic Stream

Published online by Cambridge University Press:  07 June 2016

I. S. Donaldson*
Affiliation:
Fluid Motion Laboratory, University of Manchester
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Summary

Experiments have been made to find the effect of the ratio of sting to base diameter on the base pressure of an axially symmetric body at zero incidence in a supersonic stream. The Mach number of the flow was 1·994 and the model boundary layer was turbulent. The model used was a one inch diameter circular cylinder without boat-tailing. It passed through and was supported upstream of the nozzle throat. This method of support allowed measurements to be made in the important (and hitherto unexplored) case of zero sting diameter.

As the sting to base diameter ratio was increased from 0 to 0·85, the base pressure decreased. The minimum value reached was approximately 0·8 of the value it would have at the base of a two-dimensional body with a similar ratio of boundary layer thickness to base height. The base pressure coefficient rose rapidly to zero as the ratio was further increased to unity.

Under the conditions of the experiments, with a sting to base diameter ratio of 0·4 the base pressure coefficient differed from that without a sting by approximately ten per cent. With the more modest ratio of 0·2, the difference was approximately three per cent.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society. 1955

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References

1. Chapman, D. R. An Analysis of Base Pressure at Supersonic Velocities and Comparison with Experiment. N.A.C.A. T.N. 2137 (N.A.C.A. Report 1051), 1950.Google Scholar
2. Chapman, D. R., Wimbrow, W. R. and Kester, R. H. Experimental Investigation of Base Pressure on Blunt Trailing Edge Wings at Supersonic Velocities. N.A.C.A. T.N. 2611 (N.A.C.A. Report 1109), 1952.Google Scholar