Blade row and blockage modelling in an axial compressor throughflow code
Date
2005-03
Authors
Thomas, Keegan D.
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
The objective of the thesis is to improve the performance prediction of axial
compressors, using a streamline throughflow method (STFM) code by modelling
the hub and casing wall boundary layers, and additional flow mechanisms
that occur within a blade row passage.
Blade row total pressure loss and deviation correlations are reviewed. The
effect of Mach number and the blade tip clearance gap are also reviewed as
additional loss sources.
An entrainment integral method is introduced to model the hub and casing
wall boundary layers. Various 1-dimensional test cases are performed before
implementing the integral boundary layer method into the STFM. The boundary
layers represent an area blockage throughout the compressor, similar to a
displacement thickness, but affects two velocity components. This effectively
reduces the compressor flow area by altering the hub and casing radial positions
at all stations.
The results from the final STFM code with the integral boundary layer
model, Mach number model and tip clearance model is compared against high
pressure ratio compressor test cases. The blockage results, individual blade
row and overall performance results are compared with published data.
The deviation angle curve fits developed by Roos and Aungier are compared.
There is good agreement for all parameters, except for the slope of
deviation angle with incidence angle for low solidity.
For the three compressors modelled, there is good agreement between the
blockage prediction obtained and the blockage prediction of Aungier. The
NACA 5-stage transonic compressor overall performance shows good agreement
at all speeds, except for 90% of design speed. The NACA 10-stage
subsonic compressor shows good agreement for low and medium speeds, but
needs improvement at 90% and 100% of design speeds. The NACA 8-stage transonic compressor results compared well only at low speeds.
Description
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005.
Keywords
Dissertations -- Mechanical engineering, Theses -- Mechanical engineering, Axial flow compressors, Compressors