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.