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Develop and demonstrate clearance management technologies to improve turbine engine performance, reduce emissions, and increase service life.
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- Clearances between shroud and blade tips vary over the operation and life of an engine. Wear and thermal erosion increases blade tip clearance.
- Gas path temperatures are >2500 °F, Cooling air temperatures are >1200 °F, Case temperature 600 °F with soak back.
- Actuators must react ~2000 lbf, move ~0.050 inch in 10 seconds.
- Current clearance control systems accurate to 0.015- 0.020 inch. Accuracy of <0.005 inch is goal.
- Small, lightweight active clearance control systems required. Weight < 100 lbs is goal.
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NASA Glenn Research Center is developing a unique Active Clearance Control (ACC) concept and evaluation test rig.
Purpose
- Evaluate ACC kinematic system and actuator response and accuracy under engine simulated thermal and pressure conditions to 1200 °F and 120 psi.
- Evaluate clearance sensor response and accuracy. Capacitance and microwave sensors being evaluated.
- Measure ACC system seal leakage and wear performance and identify mitigation strategies.
- Other factors to be investigated include:
- Actuator stroke, rate, accuracy, and repeatability
- System concentricity and synchronicity
- Component wear
- Secondary seal leakage
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Above: Simulated Take-off Engine Clearance Transient*. (Click image or link to view enlarged graph) |
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*From NASA/CP_2007-214995
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+ Return to the branch research page...
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and Accessibility Certification