Evaluation of factors affecting repeatability and accuracy of turbine rig test results.
Abstract
An experimental study was carried out to resolve
anomalies and to determine the sources of inaccuracies
which had hitherto been present in results from the Turbine
Test Rig at the NPS Turbopropulsion Laboratory. Internal
modifications to the rig's waterbrake dynamometer are
reported which improved the RPM control everywhere but in
the range 17,000 - 18,500 RPM. From an analysis of test
results and theoretical estimates, it was concluded that
with normal atmospheric humidity supply temperatures close
to 700°R were necessary to eliminate the influence of water
condensation on blade row performance measurements, since
the stator nozzles were supersonic. A detailed uncertainty
analysis was carried out which successfully isolated the
major causes of inaccuracies in loss data derived from rig
measurements. Recommendations were made which, if followed,
should result in repeatable and accurate measurements of
blade row losses.