Abstract
Periodical piston-driven laminar flow in an expanded pipe composed of two cylinders of different diameter was studied experimentally. Measurements of the unsteady velocity profile were made with a laser Doppler anemometer for the first three cycles. Dependency of the flow pattern on cycle number was determined from the measurements. One of the interesting results was that for the second and third intake strokes three vortices were observed in the large cylinder—two clockwise vortices and a counterclockwise vortex—while only one clockwise vortex was formed for the first intake stroke. It is thought that inertial force due to the unsteady flow condition caused such a complex flow pattern.
