Experimental investigation of lobed mixer performance

An experimental study has been conducted to investigate the effect of the g eometrical parameters of the lobed mixers on the process of mixing. The hei ght, wavelength, and penetration angle of the lobed mixers were varied to s tudy its effect on the mixing process downstream the trailing edge. A mixed ness parameter has been defined to assess quantitatively extent of mixing. Fluid velocity components, static pressure, and wall static pressures were measured for different velocity ratios at several cross sections distribute d along the axial direction downstream of the trailing edges. The results s howed that the mixedness of the lobed mixer increases with the increase of penetration angle and reaches a maximum value at a penetration angle of 20 deg. It also increases with the increase in lobed mixer height and reaches a maximum value when the height becomes equal to the wavelength. However, i ncreasing the wavelength slightly decreases lobed mixer mixedness at the vi cinity of the trailing edge. At a far distance, mixedness shows a slight in crease with the increase of the wavelength. The effects of geometrical para meters on the mixedness were similar for the tested velocity ratios. The im provement in the mixing process is attributed to the enhancement of large-s cale streamwise vortices generated downstream of the trailing edge. The eff ect of streamwise vortices was identified as producing convective transport in the crossflow plan, which increases the mean fluid interface area, thus leading to mixing enhancement.