Turbine Engine Clearance Control Systems: Current Practices and Future Directions

Test Rig for Evaluating Active Turbine Blade Tip Clearance Control Concepts

“…As Lattime and Steinetz reported in their review on clearance control systems, well over one hundred patents exist in the United States alone pertaining to blade tip clearance control. 2 However, the authors have found virtually no published experimental results for these patented systems. The authors of this work have focused their efforts on designing mechanical ACC systems that articulate the seal shroud via mechanical linkages connected to actuators that reside outside the extreme environment of the HPT.…”

“…2 Maximum tip clearance changes due to axisymmetric and asymmetric loads on the rotor and stator components are on the order of 0.050-in. The Federal Aviation Administration (FAA) requires that gas turbine engines have the ability to reach 95% rated takeoff power from ground idle (or from 15% rated takeoff power) in 5.0 seconds.…”

“…This clearance gives an area of 0.001-in. 2 , with the carrier width at 2.0-in., per flexure seal. Equation 4 gives a relation for the maximum mass flow of air through an area under choked conditions.…”

“…Lattime and Steinetz projected cost savings for U.S. carrier's fuel usage of over $160M for the year 2003 alone due only to a modest 1% reduction in SFC, based on 2001 average fuel prices. 2 …”

Test Rig for Evaluating Active Turbine Blade Tip Clearance Control Concepts

“…Lattime and Steinetz provided a comprehensive review on the mechanisms of tip clearance variation, their effects in gas turbine engines, methods of controlling tip clearance and the benefits associated with reducing tip clearance 2 . A review of some of the benefits of reduced tip clearance is presented here.…”