Structural Design And Experimental Study Of Mixed Gas Bearing With The Hermetically Sealed Squeeze Film Damper

With the rapid development of high speed turbine machinery,because the traditional sliding bearing and rolling bearing severe pollution,shorter working temperature range,such as limited,has been unable to meet the turbine machinery of high speed,high efficiency,high precision demand,because the gas bearing for has the advantages of low loss,no friction and no pollution,thus received extensive attention in the industry.Tilting tile mixed gas bearing is a superior type of gas bearing at present,which can improve the stability of the whole bearing rotor system by using the adaptive rotation of the bearing bush.However,the damping performance of tilting pad bearings is relatively low,so they cannot be used in high power turbine machinery.Although the traditional open extruded oil film damper has high damping characteristics,it cannot meet the oil-free environment required by gas bearings.In order to better adapt to the development requirements of high-speed rotating machinery,this paper proposes a hermetically sealed squeeze film damper(HSFD).By integrating the sealed extruded oil film damper into the tilting tile bearing as a separate module,the damping characteristics of the bearing are improved.The main work of this paper mainly includes the following aspects:(1)The working principle of the hermetically sealed squeeze film damper(HSFD)is described,and the relevant theoretical model of the damper is briefly introduced.Three kinds of HSFD with different structure are designed: S-type HSFD,single film and double film box HSFD.The design process is given in detail,and the corresponding mechanical properties of the key components of the damper are simulated.The experimental platform of damper excitation is built,and the corresponding data acquisition system and data processing system are introduced.(2)The mechanical properties of the hermetically sealed squeeze film damper with different structures S-type HSFD,single film and double film box HSFD were tested experimentally,the performance of the three kinds of damper on frequency change trend of similar,damper stiffness increased with the increase of frequency,the equivalent damping increased with the increase of the frequency decreases.Equivalent damping of double film box HSFD was obviously higher than that of the other two kinds of damper,compared with the S-type HSFD,the symmetry of the oil film box HSFD is significantly lower the frequency dependence of equivalent damping,verify the damper oil film symmetry affect damper equivalent damping frequency dependence.In addition,a large number of comparative tests are made on excitation amplitude,damping fluid viscosity,oil clearance and end clearance.(3)Introduce the working principle of radial mixed gas bearing,two different types of radial tilting tile mixed gas bearing housings were designed to install the Stype HSFD and double film box HSFD respectively,according to the condition of bearing and damper displacement changes needed to select bearing shell material,and the two radial bearing shell are related to the intensity of the simulation,Verify that the rotation and radial flexibility of the bearing housing meet the requirements.(4)A high power permanent magnet motor was designed to test the performance of mixed gas bearing with s-type HSFD.Firstly,the structure design and theoretical calculation of the porous thrust bearing used by the motor are carried out.Secondly,the permeability,bearing capacity and stiffness of thrust bearing are tested experimentally.Finally,the rotor dynamics of the assembled rotor is checked to verify the rationality of the rotor design.