Design And Optimization Of Auxiliary Backward-bladed Centrifugal Fans

Centrifugal fans are widely used in many industries, the power consumption of which is about 5% of the gross stations capacity. As in a vessel, centrifugal fans are applied to increase the pressure of the air for scavenge when the marine engine starts or operates at low loading. Increment of efficiency of the centrifugal fans means a lot for energy conservation. For this purpose, to optimize the design methods of centrifugal fans is one of the essential solutions.One dimensional design method is applied more often than the others, for it is simple and easy to comprehend. With proper choice of the parameters, the outcomes could be capable for application, but barely the best. So CFD (Computational Fluid Dynamics) analysis is carried out for optimization.This paper achieves a program, background processing algorithm of which was realized based on one dimensional designing method, for designing centrifugal fans by Flex software.The interface is composed by two parts, one is arranged for inputting performance specification and other requirements and the other is for exporting the Drawing and the performance curves of the fan.The program is used for designing an auxiliary blower for marine engine 8K90MC-C and the performance meets the requirements and the maximum efficiency of the fan designed is 71.4%, which is proved by a text. The text bench is arranged according to GB1236-2000 C type, with inlet of the blower attached by a section of pipe and the discharge free.The optimization is started with a simplified geometry of two-dimension built by AutoCAD software. The mesh is generated by Gambit software. All the 28 thousands cells.are triangles and the mesh is fine.The Multiple Reference Frame model (MRF) and RNGκ-s turbulent model is involved in the simulation. After the comparison of the simulation results to the text data, the difference of total pressure and efficiency is 0.47% and 11.4% of the text data. The simulation results indicate that efficiency of blowers increase 6.6% after the change of the cut-off and the dynamic pressure lose drops down from 14.6% to 11.2% after the optimization of the volute.