Enhancing impinging jet heat or mass transfer by fluidically generated flow pulsation

Periodic pulsation of high intensity generated by a no-moving-part fluidic oscillator located upstream from jet generating nozzles was demonstrated to enhance heating (or cooling and, because of the analogy of governing equations, also drying) by impinging hybrid-synthetic jets. The test setup was built for an envisaged application in food processing by baking or roasting. It has two nozzles, each connected to one of the two outlets of the diverter-type oscillator. The nozzles were of annular exit cross-section and operated in anti-parallel (outflow from one nozzle simultaneous with suction into the other nozzle). The investigation, focused on study of the temperature fields on a plane impingement wall visualised by thermochromic liquid crystals, revealed some unexpected effects.