Visualization of Flows behind the Lobed Forced Mixers Using the Smoke-wire Technique

Article type: Research Article

Authors: Yu, S.C.M. | Yip, T.H. | Chua, L.P.

Affiliations: Thermal and Fluids Engineering Division, School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 639798 | Thermal and Fluids Engineering Division, School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 639798.

Abstract: Flow visualization studies have been conducted using the smoke-wire technique to examine the flows behind lobed forced mixers of different trailing edge configurations (namely a square wave, semi-circular wave and a triangular wave) at a velocity ratio 1:1 across the lobe. The wake region shed by a lobe is found to be the largest with lobe geometry consisting of straight parallel sidewalls. Streamwise vortices are formed within the first four wavelengths downstream of the trailing edge in the square and semi-circular lobed mixers. These vortices are largely responsible for intense mixing at downstream locations. However, similar observation is not found in the case of triangular lobed mixer. The present visualization tests agree qualitatively with the velocity measurements obtained by authors using a laser-Doppler anemometer.

Keywords: lobed mixer smoke-wire technique

Journal: Journal of Visualization, vol. 1, no. 4, pp. 397-404, 1998