Free vortex theory for efficiency calculations from annular cascade data
- Oxford Univ. (United Kingdom). Dept. of Engineering Science
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.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 511908
- Report Number(s):
- CONF-950629-; ISSN 0889-504X; TRN: IM9736%%34
- Journal Information:
- Journal of Turbomachinery, Vol. 119, Issue 2; Conference: 40. International gas turbine and aeroengine congress and exposition, Houston, TX (United States), 5-8 Jun 1995; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
The influence of endwall contouring on the performance of a turbine nozzle guide vane
Revolutionizing Turbine Cooling with Micro-Architectures Enabled by Direct Metal Laser Sintering