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 compliant material forming a shroud;
a high-conductive material coupled to a first surface of the compliant material, the first surface facing a casing, 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;
an abradable material coupled to a second surface of the compliant material facing the fan blade; and
a controller, the controller to at least:
heat the heated substance in response to a measured clearance not satisfying a threshold value; and
cool the heated substance.
2. The thermally-actuated clearance control system of claim 1 , wherein the high-conductive material provides a barrier to the compliant material against the heated substance.
3. The thermally-actuated clearance control system of claim 1 , wherein the heated substance is hot air.
4. The thermally-actuated clearance control system of claim 1 , wherein the heated substance is hot lube oil.
5. The thermally-actuated clearance control system of claim 1 , wherein the compliant material is a high alpha material connected to fins of a low alpha material, the high alpha material associated with a high alpha coefficient and the low alpha material associated with a low alpha coefficient, the high alpha coefficient indicating a greater degree of available deflection response than the low alpha coefficient.
6. The thermally-actuated clearance control system of claim 1 , further including a proximity sensor to measure the measured clearance.
7. The thermally-actuated clearance control system of claim 1 , wherein the controller is to stop heating the heated substance in response to a second measured clearance satisfying the threshold value.
8. 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 for at least one of the compressor or the turbine, the thermally-actuated clearance control system comprising:
a compliant material forming a shroud;
a high-conductive material coupled to a first surface of the compliant material, the first surface facing a casing, 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;
an abradable material coupled to a second surface of the compliant material facing the fan blade; and
a controller, the controller to at least:
heat the heated substance in response to a measured clearance not satisfying a threshold value; and
cool the heated substance.
9. The gas turbine of claim 8 , wherein the high-conductive material provides a barrier to the compliant material against the heated substance.
10. The gas turbine of claim 8 , wherein the heated substance is hot air.
11. The gas turbine of claim 8 , wherein the heated substance is hot lube oil.
12. The gas turbine of claim 11 , wherein the compliant material is a high alpha material connected to fins of a low alpha material, the high alpha material associated with a high alpha coefficient and the low alpha material associated with a low alpha coefficient, the high alpha coefficient indicating a greater degree of available deflection response than the low alpha coefficient.
13. The gas turbine of claim 8 , further including a proximity sensor to measure the measured clearance.
14. The gas turbine of claim 8 , wherein the controller is to stop heating the heated substance in response to a second measured clearance satisfying the threshold value.
15. The gas turbine of claim 8 , further including a pre-cooler.