Abstract
A rapidly-accelerating flow has been studied experimentally in a curved pipe. In the present experiment, a flow in a curved pipe is accelerated very rapidly from the rest up to Re =4×10^4, and the unsteady distribution of axial velocity is measured by using I-type hot-wire probe. As results, in the upstream half of curved pipe, the fast flow leans toward the inside wall of curved pipe. In the downstream half, the fast flow moves from the inside to the outside wall of curved pipe. In addition, because of the effect of rapid acceleration, the secondary flow grows rapidly and the additional velocity peak of the primary flow appears near the inside wall at the final term of acceleration.
