凹坑型微织构对机械密封摩擦性能的影响

The Impact of Concave Micro-Texture on the Frictional Performance of Mechanical Seals

摘要: 针对加工有微织构的机械密封端面，依据考虑空化效应的流体动压润滑理论，构建了具有圆柱形、圆台形、正方形和棱台形4种不同形状微织构的密封间隙液膜流体动力学仿真模型，应用流体动力学求解工具Fluent研究了转速、微织构深度对机械密封的承载力和摩擦系数的影响规律，结果表明：在相同工况条件下，增大转速可以提高液膜的承载压力以及减小摩擦系数，从而提升动压效应，圆台形微织构具有更大的优势；合理改变微织构深度能够有效提升机械密封承载性能以及降低摩擦系数，当微织构深度递增时，液膜压力呈现出先升后降的趋势，当微织构深度为30 μm时液膜压力达到峰值，但圆台形微织构相较于棱台形微织构受深度影响更大。至于摩擦系数则是随着微织构深度的递增呈现出先减小后增大的趋势，当微织构深度为30 μm时摩擦系数获得最小值。由仿真结果可知，最佳微织构深度为30 μm，此时的密封间隙液膜承载力最强，摩擦系数最小，且这一最佳深度与微织构的形状无关。

Abstract: For the mechanically sealed surfaces that have been refined with micro-texturing, a hydrodynamic simulation model of the liquid film within the seal clearance, featuring four distinct micro-texturing shapes—cylindrical, circular platform, square, and prismatic platform—has been developed. This model is grounded in the principles of fluid dynamic pressure lubrication theory, which takes into account the phenomenon of cavitation. By employing Fluent, a computational fluid dynamics solver, the study investigates how variations in rotational velocity and the depth of the micro-texture affect the mechanical seal’s load-carrying capacity and friction coefficient. The findings indicate that, under identical operating conditions, an increase in rotational speed can enhance the load-carrying pressure of the liquid film and decrease the friction coefficient. This, in turn, amplifies the dynamic pressure effect. The simulation outcomes reveal that the circular platform-shaped micro-texture offers a significant advantage. A judicious adjustment in the depth of the micro-texture structure can effectively boost the mechanical seal’s bearing capacity and reduce the friction coefficient. The liquid film pressure exhibits a pattern of initial increase followed by a decrease as the depth of the micro-texture structure increases. The pressure reaches its zenith when the micro-texture depth is 30 μm. It is noteworthy that while the liquid film pressure peaks at a micro-texture depth of 30 μm, the circular platform microstructure is more influenced in this regard than the prismatic microstructure. Regarding the friction coefficient, it initially decreases and then increases with the increasing depth of the microstructure. The friction coefficient achieves its minimum at a microstructure depth of 30 μm. The simulation data suggest that an optimal microstructure depth of 30 μm is ideal, as it affords the sealing gap’s liquid film the greatest load-carrying capacity and the lowest friction coefficient. This optimal depth is independent of the microstructure’s shape, signifying that the circular platform, square, and prismatic platform micro-textures all perform equally well when optimized at a depth of 30 μm.