VCO 노즐에서 분사되는 디젤분무의 분열영역 구조 = The Structure of Break-up Zone of Diesel Spray from a VCO Nozzle

다국어 초록 (Multilingual 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 internal structure of the diesel spray from a common-rail injection system was visualised with high spatial and temporal resolution under atmospheric ambient condition at room temperature. Highly magnified spray images were presented with common-rail pressure of 39.5MPa and 112MPa from the nozzle exit to about 260 nozzle diameters downstream during injection period A short transition period was found where ligaments were formed on the disturbed liquid column surface, before atomization break-up regime appeared as injection velocity increased. In atomization regime, spray was surrounded by the short and fine ligaments, which were arranged and bent to the direction of spray penetration The internal structure of break-up zone consisted of complicatedly entangled ligaments and dispersed liquid drops. Break-up process occurred simultaneously at spray surface and core rather than gradually propagated from the spray surface. Entrained ambient air penetrating through the crevices of densely packed ligaments seemed to stretch the coherent structure and carry small droplets from the spray surface. The collapse of cavitation bubble might be a cause of ligaments forming near the nozzle exit at 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<br/>
common-rail pressure led smaller droplets as expected.<br/>

목차 (Table of Contents)

• ABSTRACT
  
• 1.서론
  
• 2.실험장치의 구성
  
• 3.실험결과 및 고찰
  
• 4.결론
  
• 후기
  
• 참고문헌