Instrument Development:

Structured Emission Thermometry (SET)

Spatially resolved, optical flame temperature and concentration measurement for engine testing and control applications

Spatially resolved, optical flame temperature and concentration measurement for engine testing and control applications

Structured Emission Thermometry (SET) provides non-contact temperature and concentration mapping at a variety of locations within a turbine engine or other combustor. A near-IR instrument has been used to measure water and soot temperatures in combustor test-stands. A mid-IR version, under development, would provide simultaneous measures of temperature and CO, CO2, and H2O concentrations and pattern factors, and thus fully characterize the combustion flow field. A UV version would provide relative concentrations of multiple radical emitters such as OH*, CH*, and CO2* for profiling of heat release and controlling combustor instabilities. When used in conjunction with tomographic reconstruction, SET can provide two-dimensional spatial profiles of these important combustion characteristics.

In SET, one or more passive fiber optic probes are used to view different parts of the hot flow field. The optical emission from each field-of-view is routed to a remote readout unit containing a compact multi-fiber spectrograph, which determines the temperature and concentration along each field-of-view based on the shape of the observed emission spectrum.

For tomographic reconstruction, overlapping fields of view are used and the readout re-constructs the 2D spatial profile in the overlapping region.

tomographic reconstruction

tomographic reconstruction

Tomographic reconstruction of temperature and H2O concentration in a liquid fueled combustor

The near-IR instrument provides simultaneous real-time measurements of H2O and soot temperatures and intensities over fourteen fields of view. It also can provide real-time spatial reconstruction. For higher spatial resolution, the fiber probes can be translated and a time averaged-spatial profile can be reconstructed. The current instrument is suitable for test-stand applications or for monitoring and control applications in stationary pre-mixed combustors, where it provides precise gas temperature measurements on a sub-Hz time scale.

NIR Readout

NIR fiber probe

References

Goldstein, N., J. H. Gruninger, F. Bien, J. Lee, "System and Method for Optically Determining Properties of Hot Fluids from the Spectral Structure of Emitted Radiation," US Patent No. 6640199 (October 28, 2003)

Goldstein, N., Adler-Golden, S., Jin, X., Lee, J., Richtsmeier, S., and Arana, C.A., "Temperature and Temperature Profile Measurements in the Combustor Flowpath Using Structured Emission Thermography," Proceeding of ASMI Turbine Expo, GT-2003-38695, June 16-19, 2003.

Goldstein, N., Arana, C. A., Bien, F., Lee, J., Gruninger, J., Anderson, T., and Glaseen, W. M., "Innovative Minimally Intrusive Sensor Technology Development for Versatile Affordable Advanced Turbine Engine Combustors," Proceeding of ASMI Tubine Expo, GT-2002-30051, June 3-6, 2002.