This paper describes a new three-dimensional theory to calculate the efficiency or loss of nozzle guide vane annular cascades from experimental area traverse measurements of the compressible downstream flow. To calculate such an efficiency, it is necessary to mix out the measured flow computationally to either a uniform state or one that is a function of radius only. When this is done by conserving momentum, mass, and energy flow, there is a remaining degree of freedom in that the radial distribution of circumferential velocity can be chosen. This extra freedom does not arise in two-dimensional cascades. The new method mixes the flow out to a free (i.e., irrotational) vortex. This is preferred to existing methods in that it gives a physically realistic flow and also provides a unique, lossless, isentropic reference flow. The annular cascade efficiency is then uniquely defined as the ratio of the mixed-out experimental kinetic energy flux to the ideal isentropic kinetic energy flux at the same mean radius static pressure. The mathematical derivation of this method is presented. This new theory has been used to process data obtained from a large, transonic, annular cascade in a blowdown tunnel. A four-hole pyramid probe, mounted on a computer-controlled traverse, has been used to map the passage flowfield downstream of the nozzle guide vanes. Losses calculated by the new method are compared with those calculated from the same data using earlier analysis methods.

1.
Amecke
J.
,
1970
, “
Anwendung der transsonischen A¨hnlichkeitsregel auf die Stro¨mung durch ebene Schaufelgitter
,”
VDI Forschungsheft
, Vol.
540
, pp.
16
28
.
2.
Denton
J. D.
,
1993
, “
Loss Mechanisms in Turbomachines
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
115
, pp.
621
656
.
3.
Dominy, R. G., and Harding, S. C., 1989, “An Investigation of Secondary Flows in Nozzle Guide Vanes,” AGARD-CP-469, Paper No. 7.
4.
Dzung
L. S.
,
1971
, “
Konsistente Mittlewerte in der Theorie der Turbomaschinen fu¨r Kompressible Medien
,”
BBC-Mitt.
, Vol.
58
, Pages
485
492
.
5.
Horlock, J. H., 1992, Combined Power Plants: Including Combined Cycle Gas Turbine, Pergamon, Oxford.
6.
Main, A. J., 1994, “Annular Turbine Cascade Aerodynamics,” DPhil thesis, Oxford University.
7.
Main, A. J., Day, C. R. B., Lock, G. D., Oldfield, M. L. G., and Rose, M. G., 1994, “Calibration of a Four-Hole Pyramid Probe for Loss Measurement in a Transonic Cascade Tunnel,” presented at the 12th Symposium on Measuring Techniques for Transonic and Supersonic Flow in Cascades and Turbomachines, Prague.
8.
Main, A. J., Day, C. R. B., Lock, G. D., Oldfield, M. L. G., and Rose, M. G., 1995, “Area Traversing Downstream of an Annular Cascade of Nozzle Guide Vanes in a Short-Duration Blowdown Tunnel Using a Four-Hole Pyramid Probe,” presented at the 1st European Conference on Turbomachinery: Fluid Dynamic and Thermodynamic Aspects, University Erlangen, Germany, Mar. 1–3.
9.
Martinez-Botas, R. F., Main, A. J., Lock, G. D., and Jones, T. V., 1993, “A Cold Heat Transfer Tunnel for Gas Turbine Research on an Annular Cascade,” ASME Paper No-93-GT-248.
10.
Martinez-Botas
R. F.
,
Lock
G. D.
, and
Jones
T. V.
,
1995
, “
Heat Transfer Measurements in an Annular Cascade of Transonic Gas Turbine Blades Using the Transient Liquid Crystal Technique
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
117
, pp.
425
431
.
11.
Nicholson, J. H., 1981, “Experimental and Theoretical Studies of the Aerodynamic and Thermal Performance of Modern Gas Turbine Blades,” D.Phil. Thesis, Oxford University.
12.
Oates, G. C., 1984, Aerodynamics of Gas Turbine and Rocket Propulsion, AIAA Education Series, pp. 185–191.
13.
Oldfield, M. L. G., Schultz, D. L., and Nicholson, J. H., 1981, “Loss Measurements Using a Fast Traverse in an ILPT Transient Cascade,” presented at the Symposium on Measuring Techniques for Transonic and Supersonic Flow in Cascades and Turbomachines, Lyon, France.
14.
Pianko, M., and Wazelt, F., eds., 1983, “Suitable-Averaging Techniques in Non-uniform Internal Flows,” AGARD Advisory Report AGARD-AR-182.
15.
Teekaram
A. J. H.
,
Forth
C. J. P.
, and
Jones
T. V.
,
1989
, “
The Use of Foreign Gas to Simulate the Effects of Density Ratios in Film Cooling
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
111
, pp.
57
62
.
This content is only available via PDF.
You do not currently have access to this content.