In this study, biodiesel effects on transient needle motion and near-exit flow characteristics of a single-orifice high-pressure diesel injector were investigated in terms needle-lift, speed, exit velocity structure under various injection pressures. Ultrafast x-ray phase-contrast imaging technique was employed study to analyze the characteristics. High-energy sub-nanosecond pulses have potential visualize inside nozzle dense supersonic which speed reaches over 600 m/s. Transient flows can...

A coaxial jet was actively controlled by a MEMS-fabricated micro flap actuator nozzle. The effect of different control modes on secondary azimuthal instabilities and the evolution streamwise vortices were investigated applying stereoscopic PIV to cross-stream plane jet. Forcing with non-symmetric modes, in particular least-stable helical mode, accelerates through enhancement instabilities. Although forcing is applied outer shear layer jet, most pronounced inner Unlike natural appear For...

The recent strict emission regulations and the necessity to reduce global CO2 levels have promoted research studies over alternative fuel combustion technologies. Dual technology is a fascinating approach as it could combine benefits of two fuels achieve high thermal efficiency with lower harmful emissions. Natural gas burns cleaner than other fossil its low price makes an attractive near-term solution. utilization natural diesel in compression ignition engine can result performance However,...

Active mixing control of gaseous coaxial jets is achieved using magnetic flap actuators arranged on the inner periphery outer annular nozzle. The spatio-temporal velocity fields and scalar are studied through a particle image velocimeter laser-induced fluorescence method. Flap motion forces shear layer to roll up into large-scale ring vortices. When momenum flux jet much larger than that central jet, also rolls vortices, which pinch off significantly. Near-field process dominated by while...

It is well known that nozzle internal geometries affect the characteristics of diesel spray and combustion. However, despite a number studies, effects are difficult to generalize. also not clear which features more important for combustion than others. To investigate these subjects, comprehensive dataset on was obtained with 20 variations multi-hole injector nozzle. The had different combinations orifice diameter, length, sac length hub-to-tip ratio, cover large range existing production...

A novel flame temperature measurement technique based on two-line OH planar laser-induced fluorescence (PLIF) is presented. In order to measure of an unsteady using a single excitation laser and ICCD camera, new conditional image processing method has been introduced. this method, ensemble-averaged intensities at the front, which are taken by two lines, used, mean each streamwise position calculated. The present thermometry applied methane/air coaxial jet flame, actively controlled...

Active control of a lifted flame was achieved using coaxial nozzle with micro magnetic flap actuators arranged on the inner periphery annular nozzle. The spatio-temporal structure studied by laser-induced fluorescence method and particle image velocimeter, while exhaust gas examined an FT-IR analyzer. Near-field vortical structures in jet are manipulated introducing disturbances directly to initial shear layer. They were generated driven square-or saw-wave signals. modified square-wave...

The lean premixed flame stabilized by a bluff-body downstream of coaxial nozzle is actively controlled using micro magnetic flap actuators attached to the outer jet noz+zle. CH radical luminescence, CO and NOx, emissions are measured assess flame, while PLIF employed elucidate control mechanism. At both full partial load conditions, which represented equivalent ratio φ = 0.72 0.48, respectively, stability also emission drastically improved without an increase NOx emission. 0.72, stable...

AbstractActive mixing control of a methane/air isothermal coaxial jet was achieved using micro magnetic flap actuators arranged on the inner surface outer annular nozzle. The spatio-temporal evolution vortical structures and scalar were studied through particle image velocimetry planar laser-induced fluorescence methods. In contrast to studies acoustic forcing, mechanical movement directly generated large-scale intense vortices. enhanced significantly by vortices formed in shear layer,...

View Video Presentation: https://doi.org/10.2514/6.2021-0458.vid Near-wall modeling for large-eddy simulation based on lattice Boltzmann method (LBM) is applied to the external flow analyses. In spite of rapid performance progress supercomputer, near-wall turbulent boundary layer still essential in order calculate high Reynolds number wall-bounded that appears an actual engineering field. has been actively studied within framework Navier-Stokes equations. However, LBM rather at its early...

The aim of this research is to explore a high efficient and low emission engine without persisting in using only fuel. authors are currently interested natural gas/diesel dual fuel with advanced diesel injection control technology which has been developed adopted for recent vehicles. It believed that the would be beneficial combustion emission. In study, performance was achieved find out specific characters engine. Natural gas injected into an intake port directly chamber changing amounts...

The purpose of this study is to realize high-efficient dual fuel combustion with natural gas and diesel fuel. Diesel was injected directly into chamber a single cylinder engine. And through micro-hole nozzle common rail system. at an intake port as premixed gas. In order distribute spray in chamber, one injection event split twice ones, where earlier than usual around TDC. exhaust emissions heat release characteristics were investigated. result show that timing amount 1^<st> significantly...

This study sought to improve the accuracy of simulating spray penetration and combustion ignition delay by means data assimilation (DA). The simulations were conducted using Reynolds-averaged Navier–Stokes (RANS) equations assimilating schlieren image data. In DA, an ensemble square root filter (EnSRF) was used build statistical model, making simulation results more accurate without any change in governing equations. Recognizing that spray-cone injection angle has a large effect on...