Papers by Keyword: Mechanical Seal

Abstract: This study details the design, assembly, and measurement processes of a modified test bench for examining sliding ring seals. We designed a test bench suitable for measuring mechanical seals, during which we first developed the concept and the design of the bench, defined the parameters to be measured and the measurement methods, and then implemented these objectives using an existing test bench. After procuring raw materials, I manufactured and assembled the necessary components, including acid-resistant and corrosion-resistant steel parts. Key machining operations were performed, such as drilling and threading, to accommodate the mechanical seals and ensure proper alignment. Following assembly, I conducted three reference measurements with varying compressive spring forces. The system's torque was measured at a consistent rotational speed of 200 RPM. Results from the frictional torque measurements revealed that the seals displayed sensitivity to compressive forces, confirming the effectiveness of the modified test bench for future seal evaluations.

Abstract: A new average flow model to analyze the lubrication characteristics of mechanical seals with parallel sealing faces is proposed. The present model determines the flow factors considering the side leakage under the operating condition equivalent to that in the mechanical seal. The correction factor for the expected hydrodynamic pressure generated by the relative motion of rough surfaces is also defined. The results are compared with those based on the Patir’s average flow model and show that the present model can be effective for the analysis of the lubrication characteristics of mechanical seals with parallel sealing faces.

Abstract: The non-contact mechanical seal end faces opening friction condition detection and the measurement of film thickness when the end faces is just-lift-off, which are always key problems for scholars engaged in sealing industry for many years, but there is no effective solution. Acoustic emission (AE) signal generated in the running process of mechanical seal end faces has a plenty of information about the faces contact state. According to this, the thickness measurement of mechanical seal and opening condition monitoring technology by using particle filter are put forward based on the acoustic emission signal. Acoustic emission sensor is installed in the stationary ring seat, used for the indirect outer detection of the dynamic and stationary rings opening condition. The acoustic emission signals are processed by particle filter technology, and then the signal features are extracted in time domain, frequency domain and wavelet packet energy. A BP neural network model is established, the features of signal characteristic used as input of the model. It is finally realized that the mechanical seal end faces opening condition was recognized and the film thickness was measured. Eddy current sensor is installed inside the stationary ring and used for direct measurement of film thickness and verify the results got from the BP neural network. Through the experiment, this method is practical and effective, and which can be used in the monitoring of mechanical seal end faces working condition in industrial field.

Abstract: In order to study the effects of operating parameters and surface topography on friction factors between the end faces for mechanical seals, a friction factor fractal model between end faces for contact mechanical seals was established based on the contact fractal model and the average film thickness fractal model, adopting fractal parameters to represent surface topography, separating friction into viscous shear friction of liquid film and contact friction of asperities, and representing the effect of actual rough surface on viscous shear stress of liquid film by introducing the contact factor. The influencing factors of friction factor for B104a-70 mechanical seal were analyzed by simulating. Results showed that the friction factor between the surfaces increases with the increases of spring pressure when the end faces are coarser, while the friction factor decreases slightly with the increases of spring pressure when the end faces are smoother. The friction factor between the faces decreases with the increases of the sealed fluid pressure, which increases approximate linearly with the increases of rotating speed, and it increases with the increases of fractal dimension of end faces and the decreases of the characteristic scale factor.

Abstract: In order to research and master the effect of surface topography on average film thickness between the end faces for mechanical seals, average film thickness fractal model between the end faces for mechanical seal was established using fractal parameters charactering surface topography characteristics, based on contact fractal model of the end face for mechanical seal, and solving micro-void volume. Effect of surface topography fractal parameters on average film thickness between the end faces for B104a-70 mechanical seal was analyzed by theoretical calculation. The results showed that fractal dimension D and characteristic length scale G of the end face had a great influence on the average film thickness h₀, and h₀ decreased with the increased of D or decreased of G; h₀ decreased rapidly with the increased of D or with the decreased of G when the end face was coarser, however, it decreased slowly with the increased of D or with the decreased of G when the end face was smoother. In normal working parameters and surface topography fractal parameters range, average film thickness between end faces was in the range of 0.27~1.7μm. Studying on the effect of the change of surface topography on average film thickness has an important significance on the predicting of operating characteristics of end faces during actual operating and the design of end faces for contact mechanical seal.

Abstract: The total deformation and contact pressure the equivalent stress of rotary and stationary rings of contact mechanical seal are numerical simulated by ANSYS workbench. The effects of spring pressure, friction coefficient, rotational speed of rotary ring, width of contact surfaces on deformation and contact pressure are analyzed. Results indicate that deformation of rotary and stationary rings increases with the increase of spring pressure and friction coefficient, however, decreases with the increase of rotational speed of rotary ring and width of contact surfaces. Contact pressure increases with the increase of spring pressure, however, decreases with the increase of friction coefficient and width of contact surfaces. The effects of spring pressure and friction coefficient on contact pressure are not obvious, and the effect of width of contact surfaces on contact pressure is very small when it is more than 3 mm.

Abstract: Prototype fast breeder reactor’s (PFBR) secondary pumps have sealing between the rotating shaft and the stationary parts to prevent cover gas leakage into ambient air. This is achieved by means of triple mechanical seals with oil as buffer fluid. The oil for cooling the mechanical seals and bearing is supplied from an external source and is re-circulated after cooling and cleaning. During testing of secondary pumps several issues related to mechanical seal arrangement, material, oil temperature and oil leakage into process side were confronted. This paper discusses the successful resolution of such issues.

Abstract: Since the measurement of mechanical seals film thickness is difficult, the condition monitoring method based on empirical mode decomposition (EMD) is proposed. EMD is a time-frequency analysis method. It is adaptive and does not need predefined decomposition basis function. The AE signal is decomposed into a series of Intrinsic mode function (IMF) with independent characteristics of different time scales and different frequency band. It is realized that the mechanical seal contact status is accurately identified through extracting the feature of correlation coefficient which is calculated between original AE signal and multi-scale Laplace wavelet.

Abstract: In this paper, a two-dimensional axisymmetric thermal stress coupling model of mechanical seal’s rotator and stator components was established by ADINA, simplification and appropriate boundary constrained condition of stator and rotator was obtained by analyzing the contact state among the seal rings. It’s shown that the contact surface is equivalent to a resource of constant thermal, temperature of contact surface rises step by step and the location of the maximum temperature getting close to the midpoint within the contact surface according to the sliding time, the temperature gradient decrease along the worksheet so that the temperature decrease accordingly in a parabolic isogram.

Abstract: Based on COMSOL Multiphysics, the temperature field of static ring, intermediate ring and rotating ring were studied. Effect of intermediate ring rotating speed and thermal conductivity on temperature were obtained. The Results of heat transfer characteristics of the non-contact intermediate rotating ring mechanical seal provide the theoretical basis for the design and application of the new mechanical seal.