LDA technique was used to investigate valve exit flow and in-cylinder flow generated by a directed intake port of a heavy duty Diesel engine under steady and unsteady conditions.
The results obtained under both steady and unsteady show the flow patterns is very sensitive to the valve lift with this type of intake port. At small valve lift, flow profile around the valve periphery is relatively uniform, the corresponding in-cylinder flow is characteristic of double vortex. With valve lift increasing, the separating region appears near the valve seat in part of the valve periphery, therefore the flow pattern begins to depend on the position around the valve periphery. As a result, the valve exit flow is almost along the elongation of intake port at the maximum lift, the corresponding in-cylinder flow behaves as a solid body of rotation.
The motion of valve seems to have little effects on the valve exit flow pattern. However, the measuring results under unsteady condition show the temporal distribution of valve exit flow velocities and the mass flow rate during the induction process is affected by the volume of the stagnation chamber mounted between the intake port and the compressing air supply.