Gas-phase toluene LIF temperature imaging near surfaces at 10 kHz

Information on transient temperature distributions is important for the study of heat transfer and reacting flows, including combustion. Laser diagnostic methods have been developed for temperature imaging purposes but so far have largely been constrained to low temporal resolution measurements. Diode-pumped solid-state lasers and high frame rate CMOS cameras have enabled the development of a gas-phase temperature imaging method based on laser-induced fluorescence of toluene. Excitation of toluene at 266 nm results in temperature-dependent fluorescence emissions that were detected in two spectral regions, yielding a temperature-dependent signal ratio that was calibrated for the range of 100 to 600°C. Experiments were performed in a well-stabilized heated nitrogen jet, seeded with toluene. The precision of the diagnostics increases with decreasing temperature due to an overall increase in signal strength. The application of this technique to measure the transient temperature field at 10 kHz frame rates in the boundary layer of a hot gas jet impinging on a cooled metal plate is demonstrated.