Turbine Tip-Clearance Measurement.
Final rept. Jul 75-Sep 77,
AVCO LYCOMING DIV STRATFORD CONN
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This report describes the analysis and measurement of turbine tip clearance over the full range of operation of an advanced gas turbine engine. The first-stage turbine of the Lycoming advanced gas generator was used as the test vehicle for analytic and experimental evaluation. Tip-clearance response of the stage was analyzed for steady-state and transient operating conditions through the use of a one-dimensional tip-clearance calculation technique. Measurement was accomplished with three laser tip-clearance measurement probes that operate on an optical beam triangulation principle. Comparison of analytic and measured tip-clearance results showed measured clearance to be tighter than predicted over the entire power spectrum. This differential was attributed primarily to a two-dimensional thermal strain distribution in the shroud which had not been accounted for by the analytic technique. Excellent correlation was obtained between the transient tip-clearance response characteristics resulting from analysis and measurement. Comparison of measured and predicted component temperatures under steady-state and transient operating conditions verified the accuracy of the thermal analysis procedure. Component distortion, as well as response to transient engine operation, was found to have significant impact on minimum operating tip clearance. Author
- Jet and Gas Turbine Engines