Optimization Design Of Centrifugalbreather Of Aero Engine Based On CFD

Aircraft engine centrifugal breather is the main components of lubricating oil recyclingsystem for mechanical, ventilation resistance and separation efficiency of centrifugal breatherdirectly affects the efficiency of the oil recovery and job characteristics. Based on the study athome and abroad, the CFD model is used to simulate the two-phase flow formed by oil andgas mixture within centrifugal breather. The Reynolds stress model is used for the simulationof air flow’s turbulent, to accommodate Reynolds stress anisotropy. Droplet particletrajectories’ simulation adoption DPM model, to simulate the movement of particles byvarious kinds of force in the air inside the centrifugal. Continuous phase wall boundary usingstandard wall functions, simulated air boundary layer flow. Discrete phase wall boundaryusing the wall film model to simulate the interaction of droplets and the wall films.Computing solutions were calculated under different ventilation flow; different rotationalshaft speed; different vents eccentricity distance; different radial plate radius, to obtain theseparation efficiency and ventilation resistance of aircraft engine centrifugal breather. Theresults showed that: the flow resistance increase with the rotary shaft speed and ventilationflow, the ventilation flow subjoin is not conducive to an increase in separation efficiency,separation efficiency with an increase in speed will be higher. Increasing the radius of theaddendum circle of radial plate lead to the raise of ventilation resistance and promote ofseparation efficiency. Vents eccentric design helps to reduce airflow resistance and weakenexports reflux phenomenon, but there is a certain reduction of separation efficiency. Inaddition, the flow lines of air flow inside the breather showing obviously bent and fold back.the ventilation air flow inside the wire bending rotation obvious, there is a big fluid vortex inthe part of region, the structural characteristics of vortex flow have a certain impact on theseparation efficiency. Improve the turbulence intensity of flow is help for separationefficiency.The study of film thickness on the wall showed that the thickness of the oil film is affect by the wall shear stress, thin film is on the places where the shear stress is high. The migrationof the oil film turn toward the edge of wall driven by the shear stress. Finally, oil film isthrown off and became larger droplets from the wall, and back to air flow when they are beingnew particles.