Vortex rings were generated by driving pistons within circular cylinders of inner diameter D = 72.8 mm at a constant velocity U0 over a distance L = D. The Reynolds number, U0L/(2m), was 2500. The flow downstream of circular and inclined exits was examined using volumetric 3-component velocimetry (V3V). The circular exit yields a standard primary vortex ring that propagates downstream at a cons...

Abstract Piston rings cause significant friction losses within internal combustion engines. Especially the first compression ring, which is pressed onto liner by high cylinder pressure, contributes significantly to total loss of piston assembly. The tribological behavior oil scraper ring mainly related pretensioning force and can lead even at low idle speed. Due this, there always a markable ri...

The oil film behavior of a series of fifteen lubricating oils was tested in a single cylinder spark ignition engine. The oil film thickness between the piston and cylinder liner of this engine was observed using the Laser Induced Fluorescence (LIF) technique. The data was examined for correlations between physical properties of the oil and characteristics of the oil film. The region of the oil ...

An analytical model describing laminar vortex ring formation in a nozzle flow generator piston/ cylinder arrangement proposed previously by the authors is extended to time-dependent velocity programs. The predictions of the model are in good agreement with the available numerical data for impulsive, linear, and trapezoidal velocity programs. We also show that properly scaled vortex circulation ...

An axisymmetric vortex-sheet model is applied to simulate an experiment of Didden (1979) in which a moving piston forces fluid from a circular tube, leading to the formation of a vortex ring. Comparison between simulation and experiment indicates that the model captures the basic features of the ring formation process. The computed results support the experimental finding that the ring trajecto...

The growth of a boundary layer at the nozzle wall during laminar vortex ring formation by a nozzle flow generator (piston/cylinder arrangement) is analysed theoretically and numerically and used for modelling the formation of real vortex rings. The predictions of the model are in good agreement with previous experimental and numerical results.