Abstract
Air is accelerated from the state of rest, steady laminar state, or steady transitional state in a circular pipe at a constant-acceleration until it reaches a predetermined cross-sectional mean velocity. The effects of the history of transient flow thus generated on the transition to turbulence and the axial propagation velocity of turbulence are investigated. The transitional Reynolds number of the transient flow is hardly affected by the cross-sectional mean velocity of the initial laminar flow. The axial propagation velocity of turbulence is the same magnitude as the value in a steady transitional pipe flow. An analytical solution derived for the axial velocity component of the transient laminar flow is compared favorably with the measured values.
