Research And Design Of Anti-Surge Control System In Wind Tunnel Compressor

In recent years,continuous high-speed wind tunnels have been successively completed and put into operation in China due to their stable flow field,high accuracy of Mach number,and long term continuous operation.This type of wind tunnel usually is driven by an axial compressor,which increases the air flow pressure by rotating and expanding,making it flow continuously in the wind tunnel,and providing pressure ratio to establish the flow field in test section.Surge is an inherent characteristic of axial compressors.During the wind tunnel test,the test conditions such as total pressure,total temperature,Mach number,and model angle were varied,which caused frequent changes in parameters such as flow passage area,compressor speed,and stator vane angle,forcing axial compressor often deviates from design situations and easily surges.Surge usually causes serious consequences such as periodic air oscillation,pressure and flowrate pulsation,and strong vibrations caused by inter-stage pressure imbalance,which endangers operational safety of axial compressor.Therefore,it is strictly forbidden for axial compressor to work in surge situation,that’s the reason for researching on anti-surge characteristics and designing control system.Based on the 0.6m continuous transonic wind tunnel built by the China Aerodynamics Research and Development Center,the surge characteristics of the axial compressor applied in the complex wind tunnel situation are researched in this paper,a surge margin line of compressor in the wind tunnel is tested,an anti-surge mode is established,and finally the anti-surge control system is developed to meet the requirements of wind tunnel applications.Firstly,the drag characteristics of compressor and 0.6m continuous transonic wind tunnel pipeline are analyzed,and surge conditions of multi-stage axial compressor and the reduction law of flowrate coefficient during variable speed situation in non-design speed is given.The flow characteristics of axial compressor are given based on the complicated and changeable pipeline system during wind tunnel test.Secondly,the surge margin line of axial compressor in 0.6m continuous transonic wind tunnel was tested,the method of reducing inlet air volume flowrate and monitoring pressure fluctuation of the axial compressor was adopted to determine the full speed range and full stator vane angle under different total pressures,that provides basis for establishing anti-surge model.Then,based on analysis of surge situation of axial compressor and the measured surge margin line,variable limit flowrate method is adopted to establish an anti-surge model for axial compressor.The calculation method of the model parameters and the antisurge cluster line setting method are given,the anti-surge control algorithm of compressor and redundant strategy applied in wind tunnel also are put forward.Finally,the hardware and software of the axial compressor anti-surge control system was developed based on principles of safety,reliability and practicality,and tests were performed in 0.6m continuous transonic wind tunnel.The debugging results show realtime discriminant and automatic control of surge situation were achieved.