Experimental Study of Rotation Effects on Grid Generated Turbulence with Different Mesh Sizes

Abstract

An extensive experimental study concerning rotation influence on grid generated turbulence was presented by the authors in ref. [1]. The present paper gives further experimental results on the subject. The experimental set up,sketched on fig. 1, is the same as that used in ref. [1]. It is based on the principle first adopted in ref. [2]. Briefly, it consists of a pipe divided into two parts: the upstream part which rotates contains a honeycomb followed by a turbulence producing grid; the downstream part is fixed and has a variable length in order to facilitate the exploration of the flow. The diameter of the pipe is 30 cm. Crossed hot wire probes are used to measure one point turbulence quantities such as Reynolds stresses and integral length scales. In ref. [1] only one flow configuration has been examined. It corresponds to a grid mesh size of M = 15 mm and a mean velocity of U = 10 m/s. With a maximum rotation rate of about 63 rad/s, these particular values of M and U enabled us to span two decades of the Rossby number Roq = ε/q²Ω (0,1 < Roq < 10), with x/M ranging from 17 to 76.