Development of experimental methods to capture the unsteady temperature field distributions in thermoacoustic devices

The design of an experimental apparatus, which enables the deployment of the Planar Laser Induced Fluorescence (PLIF) methodology in oscillatory flow conditions, was investigated. The pressure dependence of PLIF signals on the excitation wavelength of 266 nm was 5%/MPa. The PLIF signal maximum oscillation was only 0.05% even at large acoustic excitation such as 10,000 Pa, pressure amplitude. The acoustic coupling between the resonator and the loudspeaker generated a quarter-wavelength acoustic wave with the fundamental frequency of 13.1 Hz. The velocity amplitude in the hot and cold heat exchangers could be estimated from the velocity measured by hot-wire and model's porosity. PLIF signal intensity was calibrated against the temperature at the beginning of each experiment. The temperature calibration range was from 20 to 200°C. The air temperature in the cold channel dropped below 100°C, while that in the hot channel forms gradually changed from 100 to 200°C along the axial positions.