%0 Journal Article %A Schmid, Andreas %A Schneider, B. %A Boulouchos, Konstantinos %A Wigley, Graham %D 2014 %I Begell House %K direct injection gasoline engines, piezo injector, hollow cone spray, experimental, needle lift %N 10 %P 841-857 %R 10.1615/AtomizSpr.2014007329 %T EXPERIMENTAL INVESTIGATIONS ON A PIEZO-ACTIVATED HOLLOW CONE INJECTOR − PART I: MEASUREMENT OF NEEDLE LIFT AND ITS INFLUENCE ON SPRAY MORPHOLOGY %U https://www.dl.begellhouse.com/journals/6a7c7e10642258cc,0a3b96ef4b12165c,28f034b64923853d.html %V 24 %X To comply with the worldwide regulations on automotive exhaust gas standards, modern combustion methods rely on sophisticated injection systems to deliver highly reproducible spray patterns with precise control of the injected volume. The outward-opening, piezo-driven pintle injector, designed for spray guided direct injection gasoline engines, is an injector which fulfills these boundary conditions. The outward opening pintle produces a hollow cone spray formed by a dense array of distinct streaks of fuel systematically ordered around the circumference of the cone. The most significant advantage of the piezo drive is its ability for precision control of the needle. In combination with a direct injection control unit it allows a high degree of flexibility of the needle lift and lift profile. To date, the exact needle lift and its influences on spray propagation and spray shape are not yet fully understood. In this work different aspects of needle lift and the injection of an outwardly opening piezo injector have been studied: Under a microscope the needle lift of the dry injector has been measured with the help of a highspeed camera. With an Injection Analyzer the mass flow through the injector for the corresponding needle lifts has been determined. It was shown that earlier analytical investigations on the discharge coefficient for the hollow cone injector (Gavaises, M., Tonini, S., Marchi, S., Theodorakakos, A., and Bouris, D., Int. J. Engine Res., vol. 7, p. 17, 2006) are close to the experimental investigations. Furthermore, the shape of the hollow cone spray as well as the vapor phase has been investigated with the help of the shadowgraphy technique. The shadowgraphy measurements under nonevaporating conditions showed that spray shape is heavily influenced by the needle lift. The streaklike structure diminishes toward higher needle lift. The investigations under evaporating conditions showed that the vapor phase is also influenced by the needle lift, as the high local mass fraction of liquid fuel leads to a retardation in evaporation with increasing needle lift. %8 2014-09-09