Evaluation of an Electrostatic Probe Technique for Detecting Imminent Failure of Gas Turbine Engines.

摘要

Investigations conducted by the USAF established that an electrostatic probe installed in the tailpipe of a gas turbine engine might be used with suitable electrical measuring equipment to detect the presence of small metal particles entrained in the exhaust gas. If the number of particles detected per unit time could be correlated with engine distress,the system would have great practical value in detecting imminent failure. The system was evaluated on JT9D, TF30and J52experimental engines over a wide range of engine operating conditions. Probe signals were characterized for engines without known distress and in a few unplanned instances,for engines operating in a distressed condition. Time averaged particle count rates for normal engines varied over a wide range,but there was no significant correlation with engine model or operating power condition. In three of four instances,engines operating in a distressed condition yielded average particle count rates an order of magnitude higher than normal engines,but in the fourth instance the particle count rate was within the normal range. In one attempt to simulate distress by injecting particles into an engine,the probe system surprisingly did not respond. (Modified author abstract)