A Micromixer Using the Chaos of Secondary Flow: Rotation Effect of Channel on the Chaos of Secondary Flow

Yasutaka Hayamizu, Shinichiro Yanase, Shinichi Morita, Shigeru Ohtsuka, Takeshi Gonda, Kazunori Nishida, Kyoji Yamamoto

Department of Mechanical Engineering, Yonago National College of Technology, Tottori, Japan.
Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.

DOI: 10.4236/ojfd.2012.24A021                

Abstract

The micromixer, which has a rotor with a curved channel, is studied experimentally. The secondary flow in a curved channel of rectangular cross-section is investigated using PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) methods. Two walls of the channel (the inner and top walls) rotate around the center of curvature and a pressure gradient is imposed in the direction of the exit of the channel. The non-dimensional channel curvature δ=a/R is taken to be about 0.1, where 2a is the width of the channel, R the curvature radius of the channel. Other non-dimensional parameters concerned are the Dean number De=Reδ^1/2, the Reynolds number Re=qd_h/v, where q is the mean flow velocity in the channel axis direction, ν the kinematic viscosity, dh the hydraulic diameter of the channel, and the Taylor number Tr=2(2δ)^1/2Ωa²/(δv), where Ω is the angular velocity of the rotor. Photographs of the flow in a cross-section at 180° downstream from the curved channel entrance are taken by changing the flux (De) at a constant rotational speed (Tr) of the channel walls. It is found that good mixing performance is obtained in the case of De≤0.1|Tr| and for that case secondary flows show chaotic behaviors. And then we have confirmed the occurrence of reversal of the mean axial flow.

Keywords

Chaos; Rotation Effect; Secondary Flow; PIV; LIF

Conflicts of Interest

The authors declare no conflicts of interest.

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