<DOC>
<DOCNO>
588
</DOCNO>
<TITLE>
compressor operation with one or more blade rows stalled .
</TITLE>
<AUTHOR>
benser, w.a.
</AUTHOR>
<BIBLIO>
naca rm e56b03b, 1956 . chapter xiii
</BIBLIO>
<TEXT>
an analysis of the part-speed operating problems of high-pressure-ratio
ratio multistage axial-flow compressors was made by means of a
simplified stage-stacking study .  the principal problems considered
were poor low-speed efficiency, multiple-valued performance characteristics
at intermediate speeds, and poor intermediate-speed compressor
surge or stall-limit characteristics . the analysis indicated that all
these problems could be attributed to discontinuities in the performance
characteristics of the front stages . such discontinuities can be due
to the type of stage stall or to a deterioration of stage performance
resulting from stall of adjacent stages .
  the effects of compromises of stage matching to favor part-speed operation
were also considered . this phase of the study indicated that such
compromises would severly reduce the complete-compressor-stall margin .
furthermore, the low-speed stage stall problem is transferred from the
inlet stages to the middle stages, which are more susceptible to
abrupt-stall characteristics .
  the analysis indicates that inlet stages having continuous performance
characteristics at their stall points are desirable with respect to
part-speed compressor performance . these characteristics must, however,
be obtained when the stages are operating in the flow environment of the
multistage compressor . alleviation of part-speed operation problems may
also be obtained by improvement in either stage flow range or stage-loading
margin .
  the results of this analysis are only qualitative . the trends obtained,
however, are in agreement with those obtained from experimental
studies of high-pressure-ratio multistage axial-flow compressors, and
the results are valuable in developing an understanding of the off-design
problem . in addition to these stage-matching studies, a general
discussion of variable-geometry features such as air bleed and adjustable
blades is included .
</TEXT>
</DOC>
