Team

To understand the transport phenomena in combustion system, simultaneously measured velocity and temperature fields are crucial to calculate turbulent heat flux. PIV is well developed method for measuring gas phase velocity two dimensionally. However Rayleigh scattering to measure the temperature with PIV is suffered from the strong Mie scattering off the PIV particles and PLIF measurements using naturally occurring molecules such as OH-radicals are limited to post-flame regions and are not precise for reliable data. PLIF based on seeded tracers such as toluene or acetone is limited to low-temperature (up to 800 K maximum) regions prior to combustion. Therefore new method to measure the temperature field with PIV is required.

Method and Theory

Thermographic phosphor(TGP) is a ceramic doped with rare earth or transition metal of which spectra and/or time decay is dependent on the temperature. By seeding the TGP particles in the gas flow, velocity is measured from Mie Scattering off the particles and the temperature is measured simultaneously from the phosphorescence of the same particles. To measure the temperature, TGPs are excited with UV laser sheet and two color bands of the emission spectra will be recorded in two different cameras separately. The ratio between two color bands will be exploited to conjecture the temperature field. The calibration of the temperature will be performed in-situ with thermocouple. After developing, this measurement technique will be applied to the heat transfer problem in combustion system, such as film cooling.

Proceeding

The test rig for heated round jet and Optical setup are being developed and the phosphorescence of BAM:Eu will be analyzed spectrally and time resolve manner. To find more suitable TGPs, close interaction with chemistry department has been initiated.