Study On Axial Aerodynamic Force Of Dynamic Pressure Suspended ACM Narrow Gap Flow

In the design,manufacture and operation of dynamic pressure suspension ACM,how to accurately calculate and balance the axial aerodynamic force has always been a concern in engineering and technical personnel.The research of axial force calculation and balance method is of great practical value to the design optimization of dynamic pressure suspension ACM and the design check of thrust bearing.In order to solve the problems of low calculation accuracy and long numerical calculation time of the existing empirical formula of axial force,the numerical calculation method and empirical formula calculation method are respectively used to calculate the axial force of the dynamic pressure suspended ACM based on the analysis of the cause of axial force.A geometric model of turbine end and compressor end computing domain containing narrow gap clearance(wheel back clearance,seal clearance and bearing clearance)is established.The boundary conditions of turbine end seal inlet take into account the flow loss along the bearing to turbine end.Based on the results of numerical simulation of axial force,the original formula for calculating axial force on the back side of wheel is partially modified,and a set of formula for calculating axial force more suitable for hydrodynamic suspended ACM is summarized.In view of the dynamic pressure suspended ACM speed in the design point is run,often appear due to excessive axial load bearing damage phenomenon,to the turbine end with the compressor end research as the basis,the change rule of the axial force design under different rotational speed by adjusting the turbine wheel back sealing position to balance the machine axial force on the three kinds of solutions.The results of different schemes were compared to determine the final scheme of axial force balance,that is,through the balance structure design of the axial force of the whole machine under the medium speed,the optimal sealing position of the turbine end wheel back was the middle region of the wheel back.Finally,the simulation results show that the selected scheme meets the requirement that the axial force of the whole machine of the dynamic pressure suspended ACM can be within the design bearing capacity of the thrust bearing at each working point.