Blade tip clearance control using material with negative thermal expansion coefficients
Clearance control systems with thermal actuators are disclosed. An example thermally-actuated clearance control system for a gas turbine engine includes a compliant material; a high-conductive material coupled to a first surface of the compliant material, the high-conductive material thermally coupling the compliant material to a heated substance, the compliant material to expand radially-inward toward a fan blade when the high-conductive material provides heat; and an abradable material coupled to a second surface of the compliant material facing the fan blade.
1 . A thermally-actuated clearance control system for a gas turbine engine, the thermally-actuated clearance control system comprising:
a thermally-actuated shroud;
a sensor to measure a clearance between the thermally-actuated shroud and a fan blade; and
a controller to at least:
heat the thermally-actuated shroud in response to the measured clearance being more than a threshold; and
cool the thermally-actuated shroud in response to the measured clearance being less than the threshold,
wherein the thermally-actuated shroud is positioned with respect to a protective material, the protective material including a compliant material, an abradable material, and a high-conductive material, the high-conductive material thermally coupling the compliant material to a heated substance, the high-conductive material providing a barrier to the compliant material against the heated substance.
2 . The thermally-actuated clearance control system of claim 1 , wherein the
high-conductive material is coupled to a first surface of the compliant material, the first surface facing a casing, the compliant material to expand radially-inward toward the fan blade when the high-conductive material provides heat; and wherein the
abradable material is coupled to a second surface of the compliant material facing the fan blade.
3 . The thermally-actuated clearance control system of claim 1 , wherein the thermally-actuated shroud is positioned inside a fan case.
4 . The thermally-actuated clearance control system of claim 1 , wherein the controller is a thermal actuation controller in communication with a Full Authority Digital Engine Control.
5 . The thermally-actuated clearance control system of claim 1 , wherein the controller is to heat the thermally-actuated shroud with a flow of hot lube oil and cool the thermally-actuated shroud with a flow of cold lube oil.
6 . The thermally-actuated clearance control system of claim 1 , wherein the controller is to heat the thermally-actuated shroud with a flow of hot air and cool the thermally-actuated shroud with a flow of cool air.
7 . The thermally-actuated clearance control system of claim 1 , wherein the thermally-actuated shroud is to move radially inward when heated and radially outward when cooled.
8 . The thermally-actuated clearance control system of claim 1 , wherein the measured clearance is measured at a first time, and wherein the controller is to stop heating in response to the measured clearance, when measured at a second time, satisfying the threshold.
9 . A gas turbine comprising:
a compressor including a compressor casing and a plurality of compressor blades;
a turbine, comprising a turbine casing and a plurality of turbine blades;
a shaft rotatably coupling the compressor and the turbine; and
a thermally-actuated clearance control system comprising:
a shroud;
a sensor to measure a clearance between the shroud and a fan blade; and
a controller to at least:
heat the shroud in response to the measured clearance being more than a threshold; and
cool the shroud in response to the measured clearance being less than the threshold,
wherein the shroud is positioned with respect to a protective material the protective material including a compliant material, an abradable material, and a high-conductive material, the high-conductive material thermally coupling the compliant material to a heated substance, the high-conductive material providing a barrier to the compliant material against the heated substance.
10 . The gas turbine of claim 9 , wherein the
high-conductive material is coupled to a first surface of the compliant material, the first surface facing a casing, the compliant material to expand radially-inward toward the fan blade when the high-conductive material provides heat; and wherein the
abradable material is coupled to a second surface of the compliant material facing the fan blade.
11 . The gas turbine of claim 9 , further including a fan case, wherein the shroud is positioned inside the fan case.
12 . The gas turbine of claim 9 , wherein the controller is a thermal actuation controller in communication with a Full Authority Digital Engine Control.
13 . The gas turbine of claim 9 , wherein the controller is to heat the shroud with a flow of hot lube oil and cool the shroud with a flow of cold lube oil.
14 . The gas turbine of claim 9 , wherein the controller is to heat the shroud with a flow of hot air and cool the shroud with a flow of cool air.
15 . The gas turbine of claim 9 , wherein the measured clearance is measured at a first time, and wherein the controller is to stop heating in response to the measured clearance, when measured at a second time, satisfying the threshold.