Hydrodynamic luminescence in a model diesel injector return valve

Abstract

A sample of unadditized diesel fuel was passed through an optically accessible model diesel injector return valve, which consisted of two successive nozzles connected to an intermediate fuel gallery. The first nozzle was cylindrical, while the second nozzle was stepped. The fuel was observed to produce a multi-phase, cavitating flow and a luminous blue-violet emission at the entrance to the second nozzle hole. The flow in the upstream intermediate fuel gallery and the first nozzle hole remained single-phase. Spectral analysis of the luminous emission revealed a spectrum with thermal features containing broad spectral lines and peaks at 358, 389, 405, 412, 430 and 475 nm, suggesting that the emission was dominated by π*→π transitions in the alkylated mono-, di-, and tri-aromatics, with additional spectral contributions from CH, C2, C3 and hydrogen (H).

Modelling and prediction of cavitation erosion in GDi injectors operated with E100 fuel

“…When pressure recovers to values above the liquid's vapour pressure, vapour condenses back into liquid creating strong pressure waves, which can damage the nearby walls [9]. Remarkably, the cavitation collapse process can result in light emission and temperatures in some cases of the order of 9000 K very localised in time and space [10,11]. Given the severity of cavitation collapse, plastic deformation and/or erosion of metallic surfaces causing performance drift and/or failure in multiple industrial scenarios such as in ship propellers [12], and high pressure fuel injection systems (including pumps [13,14] and injectors [15]) have been reported.…”

Comparative study of luminescence and chemiluminescence in hydrodynamic cavitating flows and quantitative determination of hydroxyl radicals production

“…In these experiments, the flow is driven by a centrifugal pump in which cavitation is also likely to occur [25] , making a fine analysis of the role of hydrodynamic cavitation more complex. Cavitation-induced pyrolysis reactions have been recently suggested as the explanation of hydrodynamic luminescence in a Diesel injector valve [26] . A question remains, that is a direct evidence of the hydroxyl radical production yield downstream hydrodynamic cavitating reactors.…”

Hole-to-hole variations in coupled flow and spray simulation of a double-layer multi-holes diesel nozzle

“…The majority of transparent real-size nozzle investigations have been performed in simplified single-hole geometries that generally confirm the presence of geometric-induced cavitation. [12][13][14][15] Still, quantification of the liquid volume fraction and differentiation between the vapour and gaseous cavitation is an open question. On the contrary, numerical simulations can provide insight regarding the flow dynamics at a resolution that cannot be obtained with today's experimental techniques.…”