Numerical Research On The Static And Aerodynamic Heating Characteristics Of Multi-leaf Compliant Foil Bearings

Bump foil gas dynamic bearing has been successfully applied in the aerospace and other fields of high-speed rotating parts.it has the advantages of high speed limit,strong bearing capacity,good adaptability,and so on.So far,bump type gas dynamic pressure bearing has been developed to the fourth generation-multi-leaves bump type gas dynamic pressure bearing with assembly preload,and scholars at home and abroad were analyzed and tested for its performance.the bearing has better bearing performance and stability.Because of the complex structure of multi leaf foil bearings,there is no reliable standard for the design optimization of bearing structure parameters.Therefore,in this paper,the performance and aerodynamic heating of multi leaf foil gas bearing are studied.First of all,the multi leaf bump type gas dynamic pressure bearing as the research object,a bending beam model of chaff and deformation equation and film thickness equation of foil is established.On this basis,the Reynolds equation and the film thickness equation are solved by using the method of super relaxation iteration.By numerical simulation,multi leaf bump type gas dynamic distribution characteristics of bearing gas film pressure and film thickness are analysed,and bearing gas film pressure distribution and film thickness distribution and bearing capacity alter along with the shaft speed(3×104r/min-7×104r/min),lubrication gas dynamic viscosity(4.21×10-6 Pa·s-4.46×10-5Pa·s),the number of foil bearing(1-8),the gap(100?m-120?m)and eccentricity ratio(0.1-0.3)and other parameters.The results show that the gas film pressure of the multi leaf foil gas dynamic bearing is slightly higher than about 1% that of the cantilever type gas dynamic pressure bearing.With the increase of the rotational speed,the dynamic viscosity of the lubricating oil and the eccentricity,and the decrease of bearing clearance,the bearing capacity will be increased.With the increase of the number of the foil,the load capacity of the bearing is increased first and then decreased.The load capacity in the scope of the research parameters,reached the maximum when four foil.The maximum bearing capacity of multi leaf bump type gas dynamic pressure bearing increases from 22 to 32 N,higher 10 N than the cantilever type bearing.The deviation angle in different under different number of foil,foil bearing has even the deviation angle is generally lower than the foil bearing has odd,parameter range from 68 degrees down to 22 degrees,about 46 degrees.Secondly,based on static characteristics of multi-leaves bump foil bearing dynamic calculation,the energy equation is introduced,discrete equations of the coupled solution of Reynolds equation,film thickness equation and energy equation,and get the multi leaf bump type gas dynamic pressure bearing temperature field distribution law.gas bearing temperature are in the same range of calculation parameters variation of static characteristics.The results showed that the multi leaf bump type gas dynamic pressure bearing temperature distribution is slightly higher than that of the cantilever type bearing,high 1K,and the local small fluctuations.In the circumferential direction and the axial direction of the middle section,the variation trend of bearing temperature field is compared.The distribution of bearing in the circumferential direction of the highest temperature at the minimum gas film thickness,temperature at the maximum film temperature is about 5K;the lowest temperature distribution in the direction of the film thickness for the Journal of the highest and lowest in flat foil;in the axial direction,the cantilever bump type gas dynamic pressure bearing little change,and more leaf bump type gas dynamic pressure distribution of bearing as the middle axis is higher than that of the shaft end is about 2K.The temperature of the two kinds of bearings will increase with the increase of the bearing speed,the viscosity of the lubricant and the eccentricity of the rotor,and decrease with the increase of the bearing clearance.The range of increase or decrease is about 1.6%~2.3%.In a word,bearing in the bearing and operating parameters under the change of bearing static characteristics and the changes of temperature field of multi leaf bump type gas dynamic were studied in this paper provide useful technical reference for this kind of bearing design and engineering application.