Study On Cleaning Technology Of External Surface And Engine Surface Of Aircraft

Aircraft oil pollution has been a major problem in the field of aeronautical maintenance.It not only affects the appearance and performance of aircraft,but also causes corrosion to aircraft's parts.Periodic cleaning is an important policy to solve the problem,which will ensure the comprehensive performance of aircraft.Traditional ODS cleaning agents and some toxic harmful solvent cleaning agents are not suitable for the needs of the development of modern cleaning.Water based cleaning agents have been paid more and more attention because of its safety,nontoxic,environmental protection,lower cost and so on.However,because of the higher requirements of the aviation industry,only a small amount of water based cleaning products available are up to the cleaning standard and applied to the field of aircraft cleaning.In this paper,in order to solve the problem of oil pollution on the outer surface of the aircraft and the carbon deposition of the engine,we researched the surface fouling characteristics of them,and developed a water based cleaning agent named 101 for the surface cleaning of the aircraft and a cleaning system for the carbon cleaning of the aircraft engine,and the corresponding cleaning technology.The specific research contents as follows:?1?Water-based cleaning agent and the corresponding cleaning technology for the outer surface of the aircraft were systemly studied.Firstly,an anionic surfactant YL-1and a nonionic surfactant FL-1,an osmotic agent ST-1 and an inorganic additive WJ-1were introduced to form the water-based cleaning agent.The ratio of the water based compound system?YL-1:FL-1:ST-1:WJ-1=7:4:1:2?was preliminarily determined by the orthogonal test.With the single factor experiments,the viscosity and foaming ability of the water based cleaning compound system was further improved by adding1%water-soluble silicone surfactant and 0.05%defoaming agent B-234.Finally,the water based water base cleaning agent named 101 was produced.According to standard technology test,the various technical specifications of the water base cleaning agent were all qualified.What's more,its physical and chemical properties were excellent with colorless and tasteless,non-toxic,harmless,good cleaning property and so on.?2?In order to solve the problem of engine carbon deposition,first of all,we used SEM,EDS,XRD,FTIR and other instruments to analyze the contamination on engine.According to the testing results,oil pollution on the engine is mainly composed of the colloid produced by the combustion of the aviation oil,inorganic oxides and some inorganic salts.The oil pollution particles are connected to each other,and the oil contamination is loose;while the oil pollution in the surface of engine?bottom and side?are composed of partially graphitized carbon,colloidal layer,inorganic salts and oxides.In view of the carbon composition and structure characteristics of the surface area of the engine,a cleaning scheme for aircraft engine carbon deposition which combines molten salt cleaning with soaking ultrasonic cleaning was developed.First,a water based microemulsion cleaning agent named 102 with a surface tension of28.04 mN/m was successfully prepared by the combining a nonion surfactant,and an anion surfactant and other additives.All the technical standard tests of the microemulsion cleaning agent are qualified,and the physical and chemical properties of the detergent are excellent,More importanly,the microemulsion cleaning agent is safety,nontoxic,environmental friendly and high efficient.On the other hand,the NaOH-NaNO₃ system was determined for molten salt cleaning.Combining with ultrasonic cleaning,we can eventually effectively clean up the deposited carbon on engine surface.The best condition of the cleaning process as follows:the NaOH-NaNO₃ mass ratio of the molten salt system is 3:7,the cleaning temperature is300?,the immersion time of the molten salt is 30 min,the ultrasonic wave is soaked in the 102 water base cleaning agent and 10 min,and the ultrasonic condition is 40KHz.?3?In order to determine the dirts structure and properties of the air inlet system blade of the aircraft engine,the oil pollution samples were analyzed by means of XRF,SEM,EDS,FTIR,extraction test and TG.Elements identified including carbon,oxygen,silicon,sulfur,sodium,potassium,aluminum,calcium,iron,and copper.The dirt particles on the 0⁴ grade adjustable blade is mostly lump,the size is different.However,the dirt particles on the 5⁷ stage grade non adjustable static blades are small and uniform.The content of oil on the 0⁴ stage blades oil are high,which also have high polarity,and the content of 0 stage blade are high.The 4 stage blades in the middle zone of 5⁷ stage grade and 0³ stage blades,which consists of the mixed grease from the two sides and the mixed scale.The dirt on the surface of the 5⁷ stage blades have high content of hydrocarbon-type oil and polymer gum,which have low polarity.In general,it is concluded that the water based cleaning agent with strong permeability,dispersing performance,emulsifying and decontamination properties of different oils and fats will have better cleaning effect on these dirts.