Based on a series of numerical computations and model experiments on the lobed mixer

the effects of turning mixing duct on the lobed mixer performance were revealed. The experimental results show that a crescent-shaped high temperature flow area is formed at the outlet cross section caused by turning mixing duct if the length-diameter ratio of mixing duct is less than 2. And a backflow zone is also found in the center of this area which is disadvantageous to the pumping performance. However

the numerical results not only verify the air flow distribution

but also show that the turning mixing duct lower the pumping efficiency of lobed mixer

and the mixer duct length should be increased for better pumping performance. To achieve a satisfied lobed mixer performance

the length-diameter ratio should not be less than 2. The numerical results also show that the optimum length-diameter ratio of lobed mixer is 2

which may not vary with the area ratio. Compared with pipe mixer whose optimum length-diameter ratio is 6

the lobed mixer could shorten the mixing duct effectively. Furthermore

fitting relations between the pumping ratio and length-diameter ratio are also presented.