Tip clearance control system
The invention is a method for controlling blade tip clearance in a turbine engine having a flowpath extending therethrough, and a system for carrying out the method. The method includes acquiring a first nonpulsating pressure signal P C representative of tip clearance, sensing a second pressure P B substantially unaffected by tip clearance, forming an actual ratio of the acquired pressure and the sensed pressure, determining an error E having an actual component and a desired component, the actual component being a function of the actual ratio; and commanding a clearance control system to reduce the error.
1. A method for controlling blade tip clearance in a turbine engine, the engine having a flowpath extending therethrough, the method comprising
acquiring a nonpulsating pressure signal representative of tip clearance;
sensing a pressure substantially unaffected by tip clearance;
forming an actual ratio of the acquired pressure signal and the sensed pressure;
determining an error having an actual component and a desired component, the actual component being a function of the actual ratio; and
commanding a clearance control system to reduce the error.
2. The method of claim 1 wherein the acquired pressure signal is acquired from a non-flowpath site.
3. The method of claim 1 wherein the actual component of the error is a ratio of the acquired pressure signal and the sensed pressure, and the desired component of the error is a desired ratio of an acquired pressure and a sensed pressure.
4. The method of claim 1 wherein the actual component of the error is an estimated actual clearance and the desired component of the error is a desired clearance.
5. The method of claim 1 wherein the acquired pressure signal is acquired from a cavity inboard of a turbine flowpath and the sensed pressure is burner pressure.
6. A system for controlling blade tip clearance in the turbine of a turbine engine having a flowpath extending therethrough, the system comprising:
a first sensor responsive to a nonpulsating first pressure signal representative of tip clearance;
a second sensor responsive to a second pressure signal substantially unaffected by tip clearance;
a controller for
a) forming an actual ratio of the first and second pressure signals;
b) determining an error having an actual component and a desired component, the actual component being a function of the actual ratio;
c) reducing the error by issuing commands to change the first pressure signal; and
wherein the actual component of the error is an estimated actual clearance and the desired component of the error is a desired clearance.
7. The method of claim 6 wherein the first pressure signal is acquired from a cavity inboard of a turbine flowpath and the second pressure signal is sensed in an engine burner.