Study On The Performance Of Compressor Influenced By Salt Spray Corrosion In Marine Environment

Compressor is a key component to raise intake pressure for gas turbine,which can be divided into axial and centrifugal type according to the internal air flow direction.The axial compressors have been widely used in aerospace,marine,power plant and other fields with the characteristic of high efficiency and large flow quantity.Compressor is a power-costing device of the gas turbine,it will consume most of power that turbine sends when gas turbine is running.Therefore,its performance will be directly reflected in the combustion chamber and turbine,affecting the whole cycle in gas turbine.For the own characteristics of gas turbine,high speed rotating blades makes the requirements on air quality are higher and more sensitive to impurities in the air compared to other power device.Compressor is the most front equipment in gas turbine.Plenty of air will flow into it while working.For marine gas turbine working in the seas,it is extremely easy to cause the corrosion in compressor internal structure in such high humidity and salinity environment.Salt fog will cause corrosion and expire in compressor blades and other key components,which will impact the internal flow field of compressor.What’s more,the pressure ratio,efficiency,flow rate and other performance parameters of compressor will be impacted.Gas turbine fault accident caused by salt spray corrosion often happened domestic and overseas,which seriously impact the safety and economy of gas turbine.So it is significant to study on performance degradation of compressor caused by salt fog corrosion.This paper took NASA Stage67 blade shape as an example,by using the method of numerical simulation,researched and analyzed the influence in compressor caused by salt spray corrosion in marine environment.Analyzed the change of internal flow field and found out the causes of performance degradation.Relationship between the compressor performance decline and corrosion degree were further studied.Research method and content adopted in this paper were as follows:1.According to the accelerated salt spray corrosion test,simulations of ocean environment corrosion on the compressor blade material were made.Corrosion degree versus time of compressor blade material in marine environment were obtained,which provided the data basis for the following calculations.2.Grid independent verification to the calculation model in this paper were made,characteristic curve of compressor through calculation were draw,designed and experimental values were compared to verify whether the model and simulation method were correct.3.In this paper,the simulation of compressor blade corrosion were led by changing the blade surface roughness,and simulation were made to compressor with performance of speed in 100%,90%,80%,70% respectively.Study the influence of corrosion on the performance of compressor,flow field changes before and after corrosion are compared,analyze the causes of decline in compressor performance.4.Corrosions in different positions on the compressor performance were studied.According to the corrosion experimental results,calculated the effects of different corrosion degrees on performance of compressor.The relationship curve between corrosion time and performance degradation was drawn.5 The compressor performance of different tip clearance size was calculated,and analysed the cause of performance degradation.Based on the corrosion data,Compressor performance degradation caused by changing blade tip clearance which was caused by salt spray corrosion were calculated,and the curve between performance degradation and corrosion time was fitted.