Pulsatile entrance flow in a curved pipe

摘要: An experimental investitition was made of the entry flow in a curved pipe under conditions wherein pulsatile component superimposed on steady mean flow. Two experiments were conducted, one curvature ratio for αw = 12·5 and κ 372. Laser-velocimetry measurements axial secondary velocities throughout cross-section at different instants time within cycle several locations downstream from entrance.The first experiment found to be quasisteady, with varying stations proportionally instantaneous velocity, but essentially same character as low-Dean-number The second more complex, separation appearing inner bend during deceleration, starting propagating upstream toward entrance. Helical motions imbedded Dean circulation also observed, certain portions central core took jet-like structure.It suggested that classifications employed by Smith describe regimes fully-developed pipes may useful distinguish between entry-flow regimes.