Gas Flow Visualization Using Laser-induced Fluorescence

Laser-induced fluorescence (LIF) is one of the methods for visualization of mixing and velocity field of supersonic flows. The method permits almost nonintrusive study of gas flow dynamics in jet engines with a high temporal and spatial resolution. The nature of supersonic flow implies large pressure, temperature and density gradients which might introduce considerable errors into the interpretation of the images, because LIF intensity strongly depends upon excited particle fluorescence decay lifetime in addition to its number density in the medium. An excited particle quenching rate usually depends on the local gas density and temperature. Therefore, for correct interpretation of the images it is necessary to know the temperature dependence of the quenching rate constants. In this work the method is developed to measure the temperature dependence of the quenching rate constant of the fluorescing particle using LIF.