Particle-free velocity and temperature field imaging using krypton laser-induced fluorescence

Particle-free simultaneous velocimetry and thermometry of gaseous flow are demonstrated using krypton (Kr) planar laser-induced fluorescence (PLIF). Spectral properties of the Kr 5p[32]₂←←4p⁶S01 absorption profile are leveraged to obtain time-averaged 2D temperature and velocity (in the direction of the laser propagation) fields in a heated M = 0.74 turbulent jet issuing into ambient. Synthetic asymmetric Voigt profiles are fitted to the measured Kr absorption profile, and the resultant collisional widths are mapped to obtain the local temperatures. Doppler shift fields in combination with temperatures are used to obtain the corresponding velocity fields. Whereas the measured mean temperature fields agree to within 7% deviation of the computed temperature field, velocity values show a maximum of 12% deviation.