Simultaneous measurement of temperature and velocity fields using thermographic phosphor tracer particles

A simple and inexpensive measurement system is suggested to measure the temperature and velocity fields simultaneously at high temperature using thermographic phosphor tracer particles. A 385-nm UV–LED and only one high-speed camera with a CMOS sensor were used for the simultaneous measurement system. The dispersion of a confined oil jet with high temperature was investigated to validate the system. The instantaneous temperature and velocity fields were obtained when silicon oil at 200 °C was injected into a silicon oil chamber at 25 °C. The decay-slope method was used for the temperature field analysis, and the velocity field was obtained by a two-frame cross-correlation algorithm. The velocity of the injected silicon oil rapidly decreased because of the change in viscosity of the silicon oil with temperature. The selection of an appropriate interrogation window size is suggested to take the moving distance of temperature-sensitive particles into account for accurate temperature measurement. Graphical abstract