Intake valve flow patterns have been measured quantitatively using particle image velocimetry (PIV) for a commercial 4-valve diesel cylinder head and valve system. The measurements have been made for low (600 engine RPM) and higher (1000 engine RPM) speeds, and at several planes in the valve curtain area. The measurements involve double exposure photography of laser light scattered by seed particles (≅1 μm) from a laser light sheet (≅ 0.5 mm by 50 mm) through an imaging system onto silver halide film. Subsequent processing produces the local particle displacement between the two exposures. Combined with the known time interval between exposures, the displacement information can produce velocity vectors at many locations in the field of view.
The results of the experiments are shown as vector plots for each operating condition. In the plane of the illuminating laser sheet, velocity vectors representing local gas velocity are produced. From the vector plots the overall flow pattern as well as detailed quantitative velocity information can be observed. At particular locations of interest, this information can be plotted as velocity profiles normal to, say, a solid surface.
This paper extends the work recently presented at the 1993 SAE Congress (930480) by using higher engine (and hence flow) speeds, as well as probing different planes of the valve curtain parallel and transverse to the planes probed in the earlier paper. Taken together, the results provide a more complete picture of the 3-D flow patterns around the valves in this cylinder head.