Study On The Evaporation Characteristics And Heat Transfer Mechanism Of Lubricating Oil And Lubricating Oil/Gasoline Mixed Oil Film

In recent years,the power density of ICE?internal combustion engine?has been constantly enhanced.However,the highly boosted GDI engine under the low-speed high-load condition has emerged a new detonation mode called super-knock,which can damage the engine instantly.A large number of studies have shown that the lubricating oil is one of the important inducing sources of super knock.In this paper,the evaporation characteristics and heat transfer mechanism of lubricating oil film and lubricating oil/gasoline oil film are studied experimentally,which are on aluminum alloy and quartz glass test board.Combined with the heat transfer mechanism,the prediction model of mass loss rate of oil film was established.Designed a heat radiation experimental bench for oil film evaporation,and the related instruments and equipment are used to measure the data of the changes of the mass,temperature and heat radiation of the lubricating oil film and the mixed oil film under different radiation intensity,oil film thickness and attached materials.Through the analysis found:1.The evaporation process of lubricating oil film under thermal radiation is divided into slow evaporation stage,rapid evaporation stage and evaporation gel stage.In the rapid evaporation stage,the mass loss rate????"?of the oil film is almost constant,and the ???''is directly proportional to the oil film thickness???and the net heat flux density?qnet?received on the oil film surface,and inversely proportional to the thermal conductivity???of the test plate.And ???" has a linear relationship with q_net?/?.2.The evaporation characteristics and heat transfer mechanism of lubricating oil/gasoline oil film were studied,the evaporation process of the mixed oil film is divided into three stages:the transient heating stage,the balance evaporation stage,the evaporation gel stage.In the initial stage,the mass loss rate of the mixed oil film????₁"?is directly proportional to the blending ratio?a?,and the linear fitting relationship between ???₁" and e^?Q_all?/? is obtained.The evaporation characteristics of the mixed oil film in the second stage are similar to that of the lubricating oil film.However,the mass loss rate????₂"?at this stage decreases with the increase of the blending ratio.According to the related theory and data analysis,it is concluded that there exists a linear coupling relationship between ???₂" and?1-??Q_net ?/?,and the net heat flux has an important influence on the fitting relationship at this stage.