Abstract
Response of the fully developed turbulent pipe flow has been investigated to sudden change of wall condition from smooth to rough. Experimental study of mean and turbulent quantities focuses on recovery process and distance required to reach to new equilibrium state. The inner diameter and total length of the pipe flow equipment are D=70[mm] and L=12[m] (=17 ID), respectively. Ak-type roughness composed of array of square bars is employed as rough wall and velocity measurement was made by a constant temperature anemometer and a single-hot wire probe. Derivative of wall static pressure with respect to the longitudinal direction takes the minimum value at x/D=15 and then approaches asymptotically to constant for jc/D=40〜50. The mean velocity and turbulent intensity profiles suggest that the internal boundary layer reaches to the pipe center at around x/D=15.
