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Effects of Inlet Boundary Layer on Pressure Recovery, Energy Conversion and Losses in Conical Diffusers

Published online by Cambridge University Press:  28 July 2016

F. A. L. Winternitz  and
W. J. Ramsay
F. A. L. Winternitz
Affiliation:
Fluid Mechanics Division, Mechanical Engineering Research Laboratory
W. J. Ramsay
Affiliation:
Fluid Mechanics Division, Mechanical Engineering Research Laboratory
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Summary

A study has been made of the effect of inlet conditions on the performance of conical diffusers with 4:1 area ratio and 5 and 10 degrees total angle of expansion. The conditions at entry were varied by using different approach lengths of diffuser inlet diameter, and by means of projecting annular screens of woven wire cloth. With this new technique it was possible to vary the velocity distribution substantially within moderate settling lengths, and to produce velocity profiles with inflections. The suitability of the annular screen method of boundary layer generation for diffuser investigations was confirmed from the comparison with the approach length results.

Energy and pressure coefficients, as well as diffuser energy efficiency and the conversion efficiency, were found to depend on the diffuser angle β and the momentum thickness ratio at inlet θ/D0. The latter emerged as one of the chief parameters controlling diffuser performance. Variation in the inlet shape parameter H of the order of 20 per cent did not significantly affect the pressure recovery or the losses in the diffuser. For moderately thick boundary layers, θ/D0 X β<0·1, the diffuser angle could be eliminated as a parameter by plotting the pressure coefficient against θ/D0 X β. The Reynolds number based on diffuser inlet diameter was, for essentially incompressible flow, 2·5 X 105 in all tests.

Type
Research Article
Information
The Aeronautical Journal , Volume 61 , Issue 554 , February 1957 , pp. 116 - 124
Copyright
Copyright © Royal Aeronautical Society 1957

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References

1. Robertson, J. M. and Ross, D. (1949). Water Tunnel Diffuser Flow Studies, Part I—Review of Literature. Pennsylvania State College, Ordnance Research Laboratory Report No. 7958-139, 1949.Google Scholar
2. Ross, D. (1955). A New Approach to Turbulent Boundary Layer Problems. Proceedings of American Society of Civil Engineers, Vol. 81, Separate No. 604, 1955.Google Scholar
3. Peters, H. (1934). Conversion of Energy in Crosssectional Divergences under Different Conditions of Inflow. N.A.C.A. Technical Memorandum No. 737, 1934.Google Scholar
4. Robertson, J. M. and Ross, D. (1952). Effect of Entrance Conditions on Diffuser Flow. Proceedings of American Society of Civil Engineers, Vol. 78 Separate No. 141, 1952.Google Scholar
5. Klebanoff, P. S. and Diehl, Z. W. (1952). Some Features of Artificially Thickened Fully Developed Turbulent Boundary Layers with Zero Pressure Gradient. N.A.C.A. Report No. 1110, 1952.Google Scholar
6. Von Doenhoff, A. E. and Tetervin, N. (1943). Determination of General Relations for the Behaviour of Turbulent Boundary Layers. N.A.C.A. Report No. 772,1943.Google Scholar
7. Robertson, J. M. and Ross, D. (1949). Water Tunnel Diffuser Flow Studies, Part II–Experimental Research. Pennsylvania State College, Ordnance Research Laboratory Report No. 7958-143, Table III, p. 20, July 1949.Google Scholar
8. Ross, D. (1953). A New Analysis of Nikuradse's Experiments on Turbulent Flow in Smooth Pipes. Proceedings of the Third Midwestern Conference on Fluid Mechanics, University of Minnesota, pp. 651–667, 1953.Google Scholar
9. Ludwieg, H. and Tillmann, W. (1949). Untersuchungen tiber die Wandschubspannung in turbulenten Reibungsschichten. Ingenieur Archiv, Vol. 17, pp. 288–299.CrossRefGoogle Scholar
10. Ross, D. and Robertson, J. M. (1952). Water Tunnel Diffuser Flow Studies, Part HI–Analytical Research. Pennsylvania State College, Ordnance Research Laboratory Report No. 7958-230, Table A-I, p. 39, March 1952.Google Scholar