Surface temperature measurements from a stator vane doublet in a turbine afterburner flame using a YAG:Tm thermographic phosphor

Abstract

Phosphor thermometry measurements in turbine engine environments can be difficult because of high background radiation levels. To address this challenge, luminescence lifetime-based phosphor thermometry measurements were obtained using thulium-doped Y3Al5O12 (YAG:Tm) to take advantage of the emission wavelengths at 365 nm (1D2 → 3H6 transition) and at 456 nm (1D2 → 3F4 transition). At these wavelengths, turbine engine radiation background is reduced compared with emission from longer wavelength phosphors. Temperature measurements of YAG:Tm coatings were demonstrated using decay of both the 365 and 456 nm emission bands in a furnace environment up to 1400 °C. To demonstrate that reliable surface temperatures based on short-wavelength YAG:Tm emission could be obtained from the surface of an actual engine component in a high gas velocity, highly radiative environment, measurements were obtained from a YAG:Tm-coated Honeywell stator vane doublet placed in the afterburner flame exhaust stream of the augmenter-equipped General Electric J85 turbojet test engine at the University of Tennessee Space Institute (UTSI). Using a probe designed for engine insertion, spot temperature measurements were obtained by measuring luminescence decay times over a range of steady state throttle settings as well as during an engine throttle acceleration. YAG:Tm phosphor thermometry measurements of the stator vane surface in the afterburner exhaust stream using the decay of the 456 nm emission band were successfully obtained at temperatures up to almost 1300 °C. Phosphor thermometry measurements acquired with the engine probe using the decay of the 365 nm emission band were not successful at usefully high temperatures because the probe design allowed transmission of intense unfiltered silica Raman scattering that produced photomultiplier tube saturation with extended recovery times. Recommendations are made for probe modifications that will enable temperature measurements using the 365 nm emission band decay, which will be beneficial in environments with strong reflections of combustor radiation.

Wall temperature measurements at elevated pressures and high temperatures in sooting flames in a gas turbine model combustor

“…. Successful measurements have already been demonstrated for example on the cylinder head of an internal combustion engine [4], on gas turbine stator vanes [5] or for the transient temperatures on a gas turbine model combustor base plate [6].…”

Wall Temperature Measurements in a Full-Scale Gas Turbine Combustor Test Rig With Fiber Coupled Phosphor Thermometry

“…This initial spike could not be suppressed with filters and is therefore not just scattering at the laser wavelength. It has been reported before that Raman scattering and fluorescence from the fiber itself is observed especially in configurations were a single fiber is used for laser and signal delivery [10]. An excitation wavelength of 355 nm was used like in this work.…”

“…The gated PMT is an elegant and simple solution for this problem. An alternative solution could be the use of fiber bundles and spectral filtering inside the probe head, as proposed by Eldridge et al [10]. This is more costly than a single fiber setup and reduces collection efficiency.…”

“…Due to the arrangement of the combustor inside the pressure housing, a fiber coupled setup is often the only solution. Fiber coupled remote phosphor thermometry has been performed before on a stator vane doublet at atmospheric pressure [10]. A fiber bundle with different fibers for laser delivery and phosphorescence collection was used.…”

Wall Temperature Measurements in Gas Turbine Combustors With Thermographic Phosphors

“…Some applications in gas turbines have already been reported. Examples include temperatures on stator vanes [15,16] or on rotating turbine blades [17].…”