VCO노즐에서 분사되는 디젤분무의 분열영역 구조

Abstract

The break-up zone of diesel spray from a valve covered orifice (VCO) nozzle was visualized to observe the effect of injection rate on spray structure and to obtain the physical insight on the development process of transient diesel spray. the surface shape and intemal stucture of the diesel spray from a common-rail injection system was visualised with high spatial and temporal resolution under atmospheric ambient condition at room tempreature. highly magnifed spray imager were prsented with common-rail pressure of 39,5MPa and 112MPa from the nozzle exit to about 260 nozzle diameters downsteam during injection period. a short transition period was found where arranged and vent to the direction of spray penetration. the intemal structure of break-up zone consisted of complicatedly entangled ligaments and dispersed liquid drops. break-up orocess occurrde simultaneoysly at spray surface and core rather than gradually propagated from the spray surface entrained ambient air penetration through the crevices of densely packed ligaments seemed to stretch the coherent strucure and carry small droplets from the spray core, but the detailed process remains to be identified. averaged liquid drop size, which was measured at spray downstream with image processing technique, was found to decrease while injection rate increased and higher common-rail pressure led smaller droplets as expected