AN EXPERIMENTAL-STUDY OF PULSATILE PIPE-FLOW IN THE TRANSITION RANGE

The study of pulsatile flows is relevant to many areas of applications . Typical applications include aerodynamics, biofluid mechanics, wind flows, and gas transport. Transition to turbulence during pulsatile fl ow is physiologically and clinically important. It has been suggested as a possible mechanism to enhance the transport of gases during high- frequency ventilation, may be related to valvular regurgitation and he art murmurs and to post stenotic dilatation and aneurysms. Measurement s in a pulsatile pipe flow with a superimposed mean flow are reported. Data were taken in a water flow with mean Reynolds numbers in the ran ge of 0 < Re(m) < 3000, oscillating Reynolds numbers of 0 < Re(omega) < 4000, and Stokes parameter 7 < lambda < 15. Velocity profiles of var ious phases of the flow, condition for flow reversal, and pressure los ses were measured. The adequacy of a quasi-steady-state model is discu ssed. Condition for transition is determined by visually inspecting ve locity signals at the centerline.