Spectroscopic diagnostics of hydrodynamic luminescence

Luminescence intensity of vortex cavitation in a Venturi tube changing with cavitation number

“…In the cases of ultrasonic cavitation and hydrodynamic cavitation, it was believed that the chemical effect of cavitation was caused by a collapse of the spherical bubble [76] . However, in the case of hydrodynamic cavitation, experimental results on the oxidation of aqueous KI solution with a hydrodynamic cavitation setup [77] , hydrogen produced by a cavitating jet [78] , luminescence on a hydrofoil [79] , [80] , luminescence caused by a cavitating jet [81] , luminescence arising in a Venturi tube [7] and luminescence in the microchannel [82] , [83] were obtained. Although a cluster approach was proposed [84] , [85] , the shape was spherical.…”

Hydrodynamic luminescence in a model diesel injector return valve

“…Electro-luminescence is the emission of ultraviolet and visible electromagnetic radiation originating in the fluid due to electronic excitation and possible electrical breakdown occurring as a result of molecular/atomic ionization and ion/electron transfer from the fluid to the surrounding medium in response to the formation of an intense electric field at the sharp edge entrance to the nozzle hole. 30–33 The electro-luminescence signal is dependent on the stability of the electric field that sustains it, that is likely to be relatively steady-state for a steady flow around the sharp edge defining the transition from the hemispherical end of the intermediate fuel gallery to the 0.220-mm nozzle hole passage.…”

Mechanism of the Decrease in Surface Tension by Bulk Nanobubbles (Ultrafine Bubbles)

“…It has been experimentally reported that triboelectric charges appear at the liquid's surface by flow electrification under conditions of hydrodynamic cavitation. 53,54 The triboelectric charges are usually positive, according to experiments. 53,55 Thus, it might be possible that the liquid's surface is positively charged due to the flow electrification during hydrodynamic cavitation to produce bulk nanobubbles.…”

“…It has been experimentally reported that triboelectric charges appear at the liquid’s surface by flow electrification under conditions of hydrodynamic cavitation. , The triboelectric charges are usually positive, according to experiments. , Thus, it might be possible that the liquid’s surface is positively charged due to the flow electrification during hydrodynamic cavitation to produce bulk nanobubbles. Furthermore, it has been experimentally reported that surface tension is decreased by excess electric charges at the liquid’s surface if the charge concentration is sufficiently high .…”