抄録
Laminar-Turbulent transition of a boundary layer forced by a jet in the inlet region of a circular pipe was experimentally investigated. The jet was inserted radially from a small hole in the inlet region into the pipe flow periodically. Isolated turbulence patches were formed from the jets, and then they propagated downstream. Axial velocity component was measured by a hot-wire anemometer. Mean and fluctuating velocities and intermittency function were ensemble-averaged. The contour lines of the intermittency were drawn. The jet reached the central region of the pipe, then damped and disappeared as goes downstream. The jet induced a turbulent patch near the wall. The turbulent patch grew in the axial, radial and peripheral directions. The patch penetrated the boundary layer, and grew in the axial direction because of the difference of propagation velocity between leading and trailing edges.
