Influence Of Blade-root Fillet On Aerodynamic Performance Of Miniature Centrifugal Compressor

As a key component of small and medium-sized aero-jet engines,the aerodynamic performance of centrifugal compressor affects the dynamic performance of the engine directly,which in turn impacts the flighting performance of aircraft.Therefore,analysis and optimization of aerodynamic performance of the centrifugal compressor,the core component of the power unit of micro and small high-speed aircraft,is the focus of research.In this paper,the effect of fillet geometric parameters on the aerodynamic performance of a miniature centrifugal compressor with splitter blades was studied by combining numerical simulation and theoretical analysis.The main conclusions are as follows:Firstly,the influence of blade-root fillet radius on the aerodynamic performance of centrifugal compressor was studied.The results show that the curves of total pressure ratio-mass flow rate and isentropic efficiency-mass flow rate are less affected by different fillet radii.Under the same working condition,different blade-root fillet radii have great influence on the performance away from the choking point.When the mass flow rate of the compressor is 0.37kg/s,the fillet radius of the blade root increases,and the total pressure ratio of the compressor increases slightly,but the efficiency decreases mildly.The fillet radius of the blade-root should be minimized when structural strength of the blade root is satisfied.Secondly,the influence of the minimum fillet angle on the aerodynamic performance of centrifugal compressor was studied.The results show that when the minimum fillet angle of the blade root increases,the total pressure ratio of the compressor is almost constant,but the efficiency increases obvio usly.When the mass flow rate of the compressor is 0.37kg/s,for enhancing the minimum angle per 15o,the efficiency increases by about 0.38%.When the minimum fillet angle increases from 30o to 45o,the efficiency increase is 0.99%.Since the existence of blade-root fillet reduces the stress concentration,the minimum angle should not be too small or too large when weighing the influence of the structural strength,processing technology and the corner effect on the compressor’s aerodynamic performance.Thirdly,the influence of the minimum fillet angle on the aerodynamic performance of centrifugal compressor was studied.The results show that the aerodynamic performance of the centrifugal impeller is greatly affected by the minimum fillet angle of the root of splitter blades,but not by the main blades.With the increase of the minimum angle of the main blades,the aerodynamic efficiency and the total pressure ratio of the centrifugal impeller increase monotonously,but the amplitude is very small.However,with the rising of the minimum angle of the splitter blades,the efficiency of the centrifugal impeller increases and then decreases,with the minimum angle of 60o reaching the maximum value,and the change of the total pressure ratio is opposite.The variation of the minimum angle of the main blades has little influence on the performance of the compressor,but too small the minimum angle of the main blades will hinder the flow of the blade passage,resulting in the decrease of mass flow rate of the compressor under the condition of high back pressure.Considering both aerodynamic performance and structural strength,it is recommended that the minimum angle of main blades should be 45°.The minimum angle change of the splitter blades has a great influence on the performance of the compressor,mainly when the minimum angle of the splitter blades is small,which will cause the flow characteristics of the pressure surface of the splitter blades to deteriorate,thus impacting the performance of the compressor.Therefore,it is recommended that the minimum angle of the splitter blades should not be less than 45°.Finally,summarizations and conclusions were conducted in the paper,and the direction of further research was indicated.