Multiphase Computational Fluid Dynamics of Rotary Shaft Seals

Abstract

The primary task of rotary shaft seals is to prevent an unwanted fluid transfer between two areas. In shaft passages of gearboxes, for example, rotary shaft seals avoid the leakage of transmission oil to ambient air. This means the flow in the lubricant film in the sealing gap between the sealing edge and the shaft surface consists of at least two phases. Taking the phenomenon of cavitation into account, the flow consists of three phases. This study aims to provide an in-depth understanding of the multiphase flow in the lubricant film of rotary shaft seals. As experimental studies of the flow processes on a microscale have proven to be quite difficult, a simulation-based approach is applied. Computational fluid dynamics (CFD) serves to compute the transient multiphase flows in the lubricant film in the sealing gap. The computational domain is a three-dimensional microscale model of the lubricant film. The results show the transient hydrodynamic pressure buildup and the dynamic phase interactions during operation. This study provides far-reaching insights into the multiphase flow processes in the lubricant film in the sealing gap and simulation-based evidence of the lubrication and sealing mechanism of rotary shaft seals.

Multiphase Conjugate Heat Transfer Analyses on the Assembly Situation of Rotary Shaft Seals

“…according to [15]. The measured values were then fitted to the curve described by Equation ( 18) in order to determine the parameters a 1 , b 0 , b 1 and b 2 .…”

“…Thus, there is no fixed boundary between the fluid to be sealed, the oil, and the surrounding fluid, the air. For the prediction of, for example, cavitation zones in the sealing gap, this multiphase flow has already been successfully simulated in the past [14,15]. Finite element analysis (FEA) of a rotary shaft seal has already been used to analyze the radial deformation and contact pressure distribution [16][17][18].…”

“…In addition, elastohydrodynamic lubrication (EHL) simulations have also been performed [19]. In general, the focus of the EHL simulations was mainly the investigation of the flow in the sealing gap [15]. By focusing on the lubricant film in the sealing gap, many of the influencing factors, shown in Figure 2, could not be considered.…”

Thermo-Fluid–Structural Coupled Analysis of a Mechanical Seal in Extended Loss of AC Power of a Reactor Coolant Pump

“…They showed that the calculation of leakage without considering structural thermal deformation can lead to significant error [9][10][11]. Other researchers also investigated the performance of a mechanical seal considering structural thermal deformation to accurately calculate the leakage rate of the seals in mechanical devices [12][13][14].…”