Large-eddy simulation of Taylor-Couette flow in multiwedge clearance with microscale gap

With the increasing demands of load capacity and dynamic response, a new generation of gas foil bearings (GFBs), assembled from preloaded elastic multileaf foils, has been developed. Its performance has become more sensitive to shearing flow induced by the multiwedge clearance, which is distinct from the classic circular clearance. In this study, large-eddy simulation (LES) reveals the instantaneous and time-averaged Taylor-Couette flow field in a three-lobe multiwedge clearance. The results have shown that the evolution of the coherent structures and the Taylor vortex pairings are highly associated with the variable cross-section in the multiwedge clearance. Near the maximum clearance, the large-scale coherent structures form stripes around the circumference and gradually become distorted and broken as they move downstream. The additional turbulence intensity has been incited by the joints between lobes, in which the flow channel first contracts and then expands. Compared with the shearing flow in the circular clearance, which is more easily affected by the end leakage, the Taylor vortex pairings are steadier and more complete in the multiwedge clearance through secondary flow, which handicaps the end leakage effect. The multiwedge clearance has guaranteed efficient momentum and energy transport of the shearing flow compared with the circular clearance, by inducing more turbulence near the joints and ensuring the operational stability beyond this region, which is also beneficial to its adaption of the GFBs. The results obtained in this study are significant because they describe the physical mechanism of the multiwedge Taylor-Couette flow and can be used for guidance in the GFBs optimization.