Research And Optimization On Surge Characteristics Of Centrifugal Air Compressor For Vehicle Fuel Cell

Centrifugal air compressor provides air with a certain pressure ratio and flow rate for vehicle-mounted fuel cell system to ensure its normal operation.When the centrifugal air compressor runs under the condition of small flow,it will cause surge.Surge is the inherent characteristic of the centrifugal air compressor.When it happens,it will cause severe vibration of the unit,and cause great damage to the impeller and bearing structure,which can cause great safety accidents.At present,the surge factors restrict the vehicle-mounted fuel cell centrifugal air compressor working in small flow condition,there is still a lack of more in-depth research on the synchronous improvement of working efficiency and stable working range of centrifugal air compressor.So in this paper,the surge characteristics of the vehicle-mounted fuel cell centrifugal air compressor are studied and optimized,in order to obtain the research results of reducing the possibility of surge and improving the stable working range.The main research work of the paper is as follows:(1)A prototype of centrifugal air compressor with a flow/pressure ratio of80g/s/1.6 and a power/speed of 10 k W/45 krpm is developed by combining aerodynamic theory and turbomachinery design software with a vehicle-mounted fuel cell system.Taking the prototype as the research object,a physical model is established,and the performance curves of the prototype at different rotating speeds and different flow rates are made by numerical simulation,and the formation reasons of the performance curves are studied.The internal flow characteristics of the prototype under design and surge conditions are analyzed,and the performance variation law and surge characteristics of the centrifugal air compressor are revealed.(2)The variation rule of performance curves of centrifugal air compressor under different outlet installation angles,outlet width of impeller and outlet installation angles of blade diffuser are analyzed by numerical simulation.The internal flow characteristics of the prototype under different structural parameters close to the surge condition are studied,and the internal reasons affecting the surge characteristics of the centrifugal air compressor are found.Then the influence law of different structural parameters on the surge characteristics of centrifugal air compressor is revealed;(3)The influences of impeller outlet installation angle,outlet width and blade diffuser outlet installation angle on the overall performance and surge characteristics of centrifugal air compressor prototype are comprehensively analyzed,and a comprehensive optimization scheme is proposed.Numerical simulation of the optimized centrifugal air compressor is carried out.Through comparative analysis,it is found that the surge line of the optimized centrifugal air compressor moves to the direction of small flow compared with the original prototype,and the pressure ratio and efficiency at the design point are improved compared with the original prototype;(4)A 10 kW/45 krpm centrifugal air compressor prototype aerodynamic test bench is built,the aerodynamic performance test of the designed prototype is carried out,and the aerodynamic performance experimental data and performance curves of the prototype under different rotating speeds and different flow rates are obtained.By comparing the experimental and simulation results,it is discovered that both the deviation data are small,which verifies the accuracy of the numerical simulation research on the centrifugal air compressor prototype,and provides experimental verification support for the further numerical simulation research and parameter optimization research.In this paper,the performance variation law and surge characteristic variation law of the vehicle-mounted fuel cell centrifugal air compressor are studied,and the comprehensive parameter optimization is carried out,which is helpful to the design and optimization of the vehicle-mounted fuel cell centrifugal air compressor to a certain extent.And it has a certain reference value.