Passive clearance control
OwnerJack W. Wilson, Jr.inventor
Life of this patent
Estimating the term…
Abstract
The clearance between the tips of the rotor blades and the segmented shroud of a gas turbine engine is controlled by a passive clearance control that includes a support ring made from a low thermal expansion material supporting a retainer for the blade outer air seal that is slidable relative thereto so that the segments expand circumferentially and move radially to match the rate of change slope of the rotor during expansion and contraction for all engine operations. A leaf spring between the support ring and outer air seal biases the outer air seal in the radial direction and maintains the desired radial position during steady state operation of the gas turbine engine.
Claims18
A process of passively controlling a blade gap between a tip shroud and a rotor blade in a gas turbine engine, the gas turbine engine comprising a support ring secured to an engine casing, a plurality of retainer and shroud assemblies secured to the support ring and forming a segment gap between adjacent shroud segments, and a rotor blade having a tip forming the blade gap between an inner surface of the shroud segment, the process comprising the steps of:
- providing for the support ring to be made from a material having a coefficient of thermal expansion less than the material of the retainer and shroud assembly;
- providing for a slot member in one of the support ring or the retainer/shroud assembly to allow for a radial movement of the retainer/shroud assembly with respect to the support ring;
- and,
- providing for the segment gap and the slot member to be of such lengths that the blade gap remains substantially the same during a take-off mode, a reduced power mode, and a steady state mode of operating the gas turbine engine.
A passive control assembly of a blade gap in a gas turbine engine, the gas turbine engine comprising a support ring secured to an engine casing, a plurality of retainer/shroud segments secured to the support ring and forming a shroud segment gap between adjacent shroud segments, and a rotor blade having a blade tip forming the blade gap, the improvement comprising:
- radial movement means to allow for radial movement of the retainer/shroud segment with respect to the support ring;
- the support ring being made of a material having a lower coefficient of thermal expansion than that of the retainer/shroud segments;
- and,
- the segment gap being of such length that the blade gap remains substantially unchanged during operation of the gas turbine engine in the initial heat-up mode, reduce power mode, and steady state mode.
A gas turbine engine, comprising:
- a rotor blade;
- a support ring, the support ring secured within a casing of the engine;
- a plurality of shroud segment assemblies, each segment assembly secured to the support ring;
- a slot member in one of the support ring or the shroud segment assembly, the slot member allowing for radial movement of the shroud segment with respect to the support ring;
- the support ring being made of a material having a coefficient of thermal expansion less than that of the shroud segment assembly;
- a blade gap formed between a tip of the rotor blade and an inner surface of the shroud segment assembly;
- and,
- a shroud segment gap formed between adjacent shroud segment assembly, the segment gap being of such length that the blade gap remains substantially constant during operation of the engine in a take-off mode, a reduce-power mode, and a steady-state mode.
Dependencies are inferred from the claim text.