Study On The Effect Of Deswirl Incidence Angle On The Performance Of Compressor Model Stages

In the multistage centrifugal compressor, the deswirl is an indispensible stator whose aerodynamic performance has significant influence on the reliability and economical efficiency of the whole machine. And the deswirl incidence angle is the regulation beginning of the disorder flow coming from the diffuser and bend. The flow out of the bend outlet should approximately be tangent to the inlet angle of the deswirl vanes. The inappropriate design of the incidence angle will result in the impact loss, the reduce of the stage efficiency and some other phenomena like the increase of noise.In order to research for a modeling, simplicity and efficient way of deswirl design, first the empirical formula of the deswirl incidence was deduced through basic aerodynamic theory. A certain numerical model (including the impeller, vaneless diffuser and deswirl) of a centrifugal compressor was constructed. Its inner flow field was numerically simulated and calculated under off-design conditions by software CFD NUMECA. Based on the off-design performance curve and information of inner flow field, it is found that the derived entrance width of deswirl is too big and causing a flow separation on the suction side of the deswirl blade.To solve this problem, under the reference of the empirical formula, the width is reduced appropriately and the performance of the whole stage is significantly improved.