High speed infrared radiation thermometer, system, and method

• US 6,364,524 B1
• Filed: 04/09/1999
• Issued: 04/02/2002
• Est. Priority Date: 04/14/1998
• Status: Expired due to Fees

• Current Assignee: Advanced Fuel Research, Inc.
• Original Assignee: Advanced Fuel Research, Inc.
• Inventors: Markham, James R.
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Gonzalez, Madeline
• Application Number:
  US09/289,407
• Time in Patent Office: 1,089 Days
• Field of Search: 374/131, 374/144, 374/153, 374/129
• US Class Current: 374/131
• CPC Class Codes: G01J 5/0022 for sensing the radiation of moving bodies

Abstract

The high-speed radiation thermometer has an infrared measurement wavelength band that is matched to the infrared wavelength band of near-blackbody emittance of ceramic components and ceramic thermal barrier coatings used in turbine engines. It is comprised of a long wavelength infrared detector, a signal amplifier, an analog-to-digital converter, an optical system to collect radiation from the target, an optical filter, and an integral reference signal to maintain a calibrated response. A megahertz range electronic data acquisition system is connected to the radiation detector to operate on raw data obtained. Because the thermometer operates optimally at 8 to 12 μm, where emittance is near-blackbody for ceramics, interferences to measurements performed in turbine engines are minimized. The method and apparatus are optimized to enable mapping of surface temperatures on fast moving ceramic elements, and the thermometer can provide microsecond response, with inherent self-diagnostic and calibration-correction features.

Claims

1. In a temperature-monitored system, including apparatus having structure defining a combustion chamber and at least one ceramic surface therewithin, the improvement wherein said system further includes a radiation pyrometer comprising, in combination:

means for collecting and transmitting electromagnetic radiation, including a hollow core waveguide having entry and exit ends, and means for directing radiation into the hollow core of said waveguide at said entry end;

means for mounting said means for collecting and transmitting with said means for collecting disposed for receiving, and directing into said hollow waveguide core, radiation emanating from said at least one ceramic surface within said chamber;

a radiation detector that is responsive for generating electrical signals indicative of the energy of impinging radiation lying in a spectral range of 10 to 11.5 microns, said detector being operatively connected to said exit end of said waveguide for receiving radiation transmitted through said core thereof;

means for discriminating radiation, for permitting substantial passage of radiation only within said spectral range, said means for discriminating being operatively disposed for permitting substantial passage to said detector of radiation of wavelengths only within said spectral range;

data acquisition means operatively connected to receive such indicative electrical signals from said detector; and

electronic data processing means operatively connected and programmed for determining, from signals received from said data acquisition means, the temperature of said at least one ceramic surface, said data processing means being programmed to correlate measured spectral radiance to the radiance of a black body at wavelengths within said range.

2. The system of claim 1 wherein said means for mounting comprises a probe body having a cavity within which at least an entry end portion of said waveguide, and said means for directing, are mounted, said probe body defining a fluid-flow space within said cavity along said means for directing and said entry end portion of said waveguide, and having means thereon for introducing a protective fluid into said fluid-flow space therewithin.

3. The system of claim 1 wherein said means for directing radiation comprises a lens disposed adjacent said entry end of said waveguide for focusing radiation into said core thereof.

4. The system of claim 1 wherein said apparatus comprises a gas turbine engine having at least one rotor, with a multiplicity of blades thereon, driven by combustion gases;

wherein an engine case comprises said structure defining said combustion chamber; and

wherein said at least one surface comprises the surface of an internal part of said engine.

5. The system of claim 4 wherein said internal part is said at least one rotor of said engine, and wherein said at least one surface is on said rotor blades.

6. The system of claim 1 wherein said means for discriminating radiation comprises a band-pass filter.

7. The system of claim 1 wherein said radiation detector is selected from the group consisting of MCT, InSb, and DTGS detectors.

8. A radiation pyrometer comprising, in combination:

means for collecting and transmitting electromagnetic radiation, including a hollow core waveguide having entry and exit ends, and means for directing radiation into the hollow core of said waveguide at said entry end;

a radiation detector that is responsive for generating electrical signals indicative of the energy of impinging radiation lying in a spectral range of 10 to 11.5 microns, said detector being operatively connected to said exit end of said waveguide for receiving radiation transmitted through said core thereof;

means for discriminating radiation, for permitting substantial passage of radiation only within said spectral range, said means for discriminating being operatively disposed for permitting substantial passage to said detector of radiation of wavelengths only within said spectral range;

data acquisition means operatively connected to receive such indicative electrical signals from said detector; and

electronic data processing means operatively connected and programmed for determining, from signals received from said data acquisition means, the surface temperature of a ceramic body emitting radiation collected by said collecting and transmitting means, said data processing means being programmed to correlate measured spetral radiance to the radiance of a black body at wavelengths within said range.

9. The pyrometer of claim 8 wherein said means for directing radiation comprises a lens disposed adjacent said entry end of said waveguide for focusing radiation into said core thereof.

10. The pyrometer of claim 9 additionally including means for mounting comprised of a probe having a body within which said lens and an entry end portion of said waveguide are mounted.

11. The pyrometer of claim 10 wherein a fluid-flow space is defined within said probe body cavity along said means for detecting and said entry end portion of said waveguide, and wherein said probe body has means thereon for introducing a fluid into said fluid-flow space.

12. The pyrometer of claim 8 wherein said radiation detector is selected from the group consisting of MCT, InSb, and DTGS detectors.

13. The pyrometer of claim 8 wherein said means for discriminating radiation comprises a band-pass filter.

14. A method for determining the temperature of a monitored ceramic surface in a combustion gas environment, comprising the steps:

collecting radiation in a spectral range of 10 to 11.5 microns emanating from the monitored ceramic surface;

transmitting said collected radiation through the core of a hollow core waveguide to a radiation detector that is responsive for generating electrical signals indicative of the energy of impinging radiation lying in said spectral range; and

processing said generated signals, using data processing means programmed to correlate measured spectral radiance to the radiance of a black body at wavelengths within said range, so as to determine therefrom the temperature of said monitored ceramic surface.

15. The method of claim 14 wherein said monitored surface comprises a heated internal part of an operating gas turbine engine having at least one rotor, with multiplicity of blades, driver by combustion gases.

16. The method of claim 15 wherein said monitored surface is on said rotor blades.

17. The method of claim 14 including the additional step of bathing, with a protective fluid, at least the portion of the waveguide that is proximate to said monitored surface.

18. The method of claim 17 wherein said protective fluid serves a cooling function, a cleaning function, or both functions.