| Summary: | Accurate prediction of overall performance is vital if
the extremely high design and development costs of modern
high speed compressors are to be minimised. This fact,
which is not novel, has led to the development of many
computer programmes for such prediction. However, the most
useful of these are proprietary. Some of those that are
accessible in the open literature are of limited
application to high performance axial compressors. This is
mainly because they cannot reliably handle the transonic
flows which characterise modern designs; nor are they
generally easy to use from an interactive stand point.
Accordingly, this report describes the origination of
a streamline curvature programme for compressor performance
prediction which attempts to bridge the gap in the existing
literature base.
The correlations used allow the package to be applied
to more recent compressors at the highest level of the
technology.
In general, the programme is both interactive and
fully modular. The former makes it easy for the user to
access the programme quickly and effectively whilst the
latter facilitates the use, for example, of alternative
loss and deviation models to those prescribed within the
programme.
A further important feature of this new programme is
its flexibility. For example, it can be used in three
modes: firstly, as an analysis programme for performance
prediction of compressors of known geometry; secondly, as a
design/development tool to assess the likely performance
changes occasioned by the introduction of geometrical
variations in both blading and annulus shape; thirdly, as a
straight design programme for new compressors provided a
project analysis has been carried out beforehand.
In the first two modes of operation, the programme
requires details of standard blading, annulus geometry,
design mass flow and pressure ratio. In the third, the user
is free to prescribe his own blade shapes.
The combined features described were introduced to
make the package an ideal teaching tool. In this respect it
should be emphasised that the complete novice to axial
compressor design and performance assessment would
experience difficulties using the package. However, the
user who has some background, perhaps through lectures or
in an appropriate industrial environment would quickly
become adept.
Against this background, whilst the programme is very
interactive, it cannot claim, in its own right, to be an
Expert System. The latter capability, however, can with
some development easily be built in at a later stage.
In order to minimise the time required accessing the
programme, the report includes a comprehensive "user-
guide".
The validity of the prediction method is tested
against an actual transonic compressor of known
performance. The output is various and includes graphical
presentation of all significant design/performance
parameters throughout the compressor, including the
compressor overall characteristic.
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