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Calculation of the Flow Field Downstream of the Fan Nozzle of a Turbofan Aero Engine

Published online by Cambridge University Press:  04 July 2016

P. G. Street
P. G. Street*
Affiliation:
National Gas Turbine Establishment
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Extract

The pursuit of better economics for subsonic transport aircraft has led in recent years to the development of high by-pass ratio turbofan aero engines. The improved efficiency of these engines results mainly from an improvement in the propulsive, or Froude efficiency brought about by the use of an increased airflow with a smaller jet velocity for a given thrust level. The specific thrust (thrust per unit airflow) for a high by-pass ratio engine is thus appreciably lower than for a conventional turbojet so that the ratio of engine gross thrust to installed net thrust is higher. Typically, for an engine of unit by-pass ratio, the ratio of gross to net thrust is about 1·6 under cruise conditions, while for an engine of by-pass ratio five it is between 2·6 and 3. Losses in the exhaust system effectively act on the gross thrust level so that any inefficiency is magnified by the gross to net thrust ratio. Thus the high values of this ratio in the new high by-pass engines render losses in the exhaust system of especial significance.

Type
Technical Notes
Information
The Aeronautical Journal , Volume 74 , Issue 720 , December 1970 , pp. 983 - 987
Copyright
Copyright © Royal Aeronautical Society 1970 

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References

1. Guderly, G. The method of characteristics for plane and axisymmetric supersonic flows. RAE Library Translation No 138. December 1946.Google Scholar
2. Prandtl, L., Busemann, A., ProfessorStodola, A. (editor). Approximate graphical methods for determining two dimensional supersonic flows. Festschrift pp. 499–509, Zurich, 1929. Available as TIL Trans. 5111.Google Scholar
3. Kantrowitz, A. R. The characteristic method for steady supersonic flows. Lecture notes given at MIT, Private communication from L. F. Crabtree, RAE, Farnborough. 1960.Google Scholar
4. Street, P. G. A digital computer programme for the calculation of annular or two-dimensional supersonic potential flow in a duct by the method of characteristics. ARC CP No 649, NGTE M354, May 1962.Google Scholar
5. Sqn. Ldr.Willcocks, H. J. and Herd, R. J. A computer programme for the analysis of nozzle performance with or without supersonic external flow. NGTE internal publication, January 1964.Google Scholar
6. Stratford, B. S. and Beavers, G. S. The calculation of the compressible turbulent boundary layer in an arbitrary pressuregradient—acorrelationofcertainprevious methods. ARC R and M No 3207, NGTE M330, September, 1959.Google Scholar
7. Compressible airflow:graphs. Prepared on behalf of the Aeronautical Research Council, London. Oxford University Press, 1954.Google Scholar