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Download or read book Flow Characteristics of Gas-blast Fuel Injectors for Direct-injection Compression-ignition Engines written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural gas has a high auto-ignition temperature, therefore natural gas engines use an ignition source to promote combustion. The high-pressure direction-injection (HPDI) systems available use small diesel injections prior to the main gas injection. A new series of HPDI injectors have been developed that inject diesel and gas simultaneously through the same holes. In order to understand and control injection and combustion behavior in an engine, it is essential to understand how injection mass is related to the diesel/gas ratio and injection command parameters. Three prototype injectors are examined. "Prototype B" most closely resembles a standard J36 HPDI injector, but has a modified diesel needle that injects diesel internally into a common diesel/gas reservoir. Prototypes "CS & CSX" have the diesel needle eliminated and replaced with a flow restrictor. The pressure difference between the diesel and the gas controls the quantity of diesel injected. A single pulse width (GPW) for the gas needle controls the fuel quantities. An injection visualization chamber (IVC) was developed for flow measurements and optical characterization of injections into a chamber at pressures up to 80 bar. Diesel and natural gas are replaced by VISCOR® and nitrogen to study non-reacting flows. A novel feature of the IVC is a retracting shroud that allows the injector to reach steady-state prior to imaging. For low commanded injection duration (GPW less than 0.60 ms), the relation between GPW and injected mass is non-linear, for all injectors tested. For gas pulse widths greater than 0.65 ms the Co-injectors exhibit approximately linear behavior with higher diesel fuelling quantities lowering gas flow quantities. All Co-injectors are compared to baseline gas flow quantities of a standard J36 to show design difference effects on flow quantities. The sensitivity of gas flow to diesel in injection quantities, as well as the discharge coefficient are computed and theoretically modeled for each.