Through-Flow Models for Mass and Momentum-Averaged Variables
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Authors
Hirsch, Charles
Dring, Robert P.
Subjects
Turbomachinery Analysis Through Flow Calculations Compressor Blockage
Advisors
Date of Issue
1985-09
Date
September 1985
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
The turbomachinery through-flow equations are reformulated for mass and momentum averaged quantities. The background of this analysis is the need for an improved assessment of the accuracy of through-flow computations. Traditional through-f low analyses are based on density weighted averaged quantities reducing to an area average in incompressible flows. On the other hand, experimental data are usually evaluated under the form of mass averaged quantities, particularly with regard to the overall energy balance and efficiency estimations. The transition between these two sets of quantities is usually taken into account by introducing an averaged aerodynamic blockage factor in addition the blade blockage factor resulting from the densityaveraged quantities. The present analysis provides a rigorous derivation for the momentum averaged flow quantities and shows that some strong assumptions on the nature of the non axissymmetric flow components are necessary in order to justify the current practice of introduction of aerodynamic blockage. The recent availability of detailed flow data in single and two stage axial compressors allows a partial validation of these assumptions, by the comparison of the various non-axisymmetric components. In addition some guidelines are provided relating the blockage factors to wake and loss coefficients.
Type
Technical Report
Description
Final Report for Period of June 1985 - September 1985
Series/Report No
Department
Aeronautics
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
NPS67-85-012CR
Sponsors
Air-Breathing Propulsion Research Program under Naval Air Systems Command, AIR31OE
Funder
Format
72 p.
Citation
Distribution Statement
Approved for public release; distribution unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, it may not be copyrighted.