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This paper describes an experimental study aimed at the characterization of the steady-state tumble motion in the cylinder of an engine using stereoscopic particle image velocimetry (Stereo-PIV). More specifically, a pentroof four valves gasoline direct injection (GDI) engine head was mounted on a modified FEV steady-state flow rig for applying Stereo-PIV at different measurement vertical tumble planes at mid cylinder, mid injector and mid valve. The flow field was described by the distribution of the ensemble average flow patterns for 1000 pairs of images for every case, vorticity contours, turbulent kinetic energy and tumble ratio. The results revealed that the higher velocities acquired at the mid valve plane improved the turbulent kinetic energy and tumble ratio compared to the other planes. There was a good level of agreement between direct and indirect methods used for calculating the tumble ratio.This paper describes an experimental study aimed at the characterization of the steady-state tumble motion in the cylinder of an engine using stereoscopic particle image velocimetry (Stereo-PIV). More specifically, a pentroof four valves gasoline direct injection (GDI) engine head was mounted on a modified FEV steady-state flow rig for applying Stereo-PIV at different measurement vertical tumble planes at mid cylinder, mid injector and mid valve. The flow field was described by the distribution of the ensemble average flow patterns for 1000 pairs of images for every case, vorticity contours, turbulent kinetic energy and tumble ratio. The results revealed that the higher velocities acquired at the mid valve plane improved the turbulent kinetic energy and tumble ratio compared to the other planes. There was a good level of agreement between direct and indirect methods used for calculating the tumble ratio.This paper describes an experimental study aimed at the characterization of the steady-state tumble motion in the cylinder of an engine using stereoscopic particle image velocimetry (Stereo-PIV). More specifically, a pentroof four valves gasoline direct injection (GDI) engine head was mounted on a modified FEV steady-state flow rig for applying Stereo-PIV at different measurement vertical tumble planes at mid cylinder, mid injector and mid valve. The flow field was described by the distribution of the ensemble average flow patterns for 1000 pairs of images for every case, vorticity contours, turbulent kinetic energy and tumble ratio. The results revealed that the higher velocities acquired at the mid valve plane improved the turbulent kinetic energy and tumble ratio compared to the other planes. There was a good level of agreement between direct and indirect methods used for calculating the tumble ratio.This paper describes an experimental study aimed at the characterization of the steady-state tumble motion in the cylinder of an engine using stereoscopic particle image velocimetry (Stereo-PIV). More specifically, a pentroof four valves gasoline direct injection (GDI) engine head was mounted on a modified FEV steady-state flow rig for applying Stereo-PIV at different measurement vertical tumble planes at mid cylinder, mid injector and mid valve. The flow field was described by the distribution of the ensemble average flow patterns for 1000 pairs of images for every case, vorticity contours, turbulent kinetic energy and tumble ratio. The results revealed that the higher velocities acquired at the mid valve plane improved the turbulent kinetic energy and tumble ratio compared to the other planes. There was a good level of agreement between direct and indirect methods used for calculating the tumble ratio. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of flame propagation through a partially-premixed flow following ignition. A combination of simultaneous high-speed acetone planar laser induced fluorescence (PLIF) and stereoscopic particle image velocimetry (SPIV) was utilized for time-resolved measurements of mixture fraction, flow field and flame position. This provides access to the major quantities needed to characterize non-premixed flames. High quality mixture fraction measurements with signal-to-noise ratios up to 120 for unity mixture fraction were made feasible using a combination of a conventional high-speed laser at 10 kHz for LIF excitation and a wavelet based de-noising algorithm to reject camera noise. It was observed that flame propagation in the far-field of a partially-premixed jet takes place in a premixed mode, with the flame propagating through highly stratified mixtures until it approaches locations containing mixtures outside the flammability limits. In these areas the flame recedes and further propagation is controlled by mixing processes of air and fuel. Even though flame propagation is then mixing-controlled, the flame is not observed to switch into a non-premixed mode. Instead, mixing ahead of the flame takes place until locally premixed flammable mixtures are recovered for subsequent flame propagation. [ABSTRACT FROM AUTHOR]