Analysis of Mechanical Seal Leakage within Hydrostatic on Nuclear Reactor Coolant Pump

2014 ◽  
Vol 496-500 ◽  
pp. 990-994 ◽  
Author(s):  
Hai Yang Zhang ◽  
Wei Bing Zhu ◽  
Zhou Gang
Keyword(s):  
Centrifugal Force ◽  
Nuclear Reactor ◽  
Hydrodynamic Lubrication ◽  
Structural Characteristics ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Coolant Pump ◽  
Turning Angle ◽  
Hydrodynamic Lubrication Theory ◽  
Turning Radius

According to the fluid hydrodynamic lubrication theory, and the structural characteristics of the convergence gap seal is combined, the effect of differential pressure and centrifugal force should be considered, then the convergent wedge gap mechanical seals flow field numerical model is established and the influence of the leakage factors are researched, including the geometric parameters and operating parameters. Research has shown that the amount of leakage and the seal clearance were positively correlated. And the larger turning Angle is, the bigger correlation becomes, however, it is negatively correlated with speed and turning radius, the seal leakage is impeded by the centrifugal force and the larger turning radius is, the smaller leakage becomes.

scholarly journals Improvement of Reliability and Ecological Safety of NPP Reactor Coolant Pump Seals

2020 ◽  
pp. 47-55
Author(s):  
S. Shevchenko ◽  
O. Shevchenko
Keyword(s):  
High Pressure ◽  
Flow Characteristics ◽  
Environmental Safety ◽  
Mechanical Seal ◽  
Ecological Safety ◽  
Mechanical Seals ◽  
Coolant Pump ◽  
Reactor Coolant ◽  
Optimal Value ◽  
Contact Surfaces

The paper presents the analysis of existing designs of NPP reactor coolant pumps (RCP) rotor sealing systems. The most common design solutions of sealing units that provide the necessary tightness, reliability and service life under high pressure, temperature and sliding speeds typical for RCP, as well as trends for their improvement to increase tightness and environmental safety of activities were identified. Designs of impulse seals with a self-adjusting clearance are presented as the most promising assemblies for sealing pump shafts with high parameters. A computer model of impulse mechanical seal as an automatic control system is proposed. A framework for calculating impulse mechanical seals has been developed, allowing the choice of their main geometric parameters to ensure the optimal value of the mechanical clearance and the friction moment on the sealing contact surfaces. Expressions are obtained for constructing the static and flow characteristics of a impulse mechanical seal, the condition for its dynamic stability is determined. The paper presents the shaft sealing system of RCP, main nodes of which are several stages of impulse mechanical seals with a self-regulating clearance.

Research on frog-inspired swimming robot driven by pneumatic muscles

Robotica ◽  
2021 ◽  
pp. 1-11
Author(s):  
Jizhuang Fan ◽  
Shuqi Wang ◽  
Yi Wang ◽  
Ge Li ◽  
Jie Zhao ◽  
...  
Keyword(s):  
Control System ◽  
Optimization Design ◽  
Simulation Analysis ◽  
Structural Characteristics ◽  
Structure Design ◽  
The Body ◽  
Turning Angle ◽  
Pneumatic Muscles ◽  
Turning Radius ◽  
Water Seal

Abstract This article designs a frog-inspired swimming robot based on pneumatic muscles. The musculoskeletal characteristics of the frog are refined and used as the basis for the design of the robot joint structure and movement mode. The posture adjustment module, joint water seal, and power system are designed to meet the robot’s motion requirements, and the structure optimization design of the robot is completed by combining simulation analysis. The body length of the robot is about 710 mm, and the overall mass is 10 kg. Combining the structural characteristics of the robot, the control system is built to realize the frog-like motion. The robot’s propulsion speed is about 0.6 m/s, the propulsion distance reaches 2.4 m, the turning angle is 30°, and the turning radius is 0.6 m. The prototype experiment verifies the rationality of the frog-inspired swimming robot structure design and the reliability of the control system and water seal.

A Thermo-hydrodynamic lubrication model of a mechanical seal modified by equivalent film thickness

2020 ◽  
Vol 21 (6) ◽  
pp. 622
Author(s):  
Xiuying Wang ◽  
Dapeng Zhi ◽  
Chengtao Yu ◽  
Yu Chen
Keyword(s):  
Film Thickness ◽  
Hydrodynamic Lubrication ◽  
Optimization Method ◽  
Textured Surface ◽  
Mechanical Seal ◽  
Multi Objective Optimization ◽  
Mechanical Seals ◽  
Equivalent Thickness ◽  
Simulation Accuracy ◽  
Multi Objective

An effective way to improve the combined performance of mechanical seals is to optimize their surface textures using multi-objective optimization method. For compatibility with the multi-objective optimization algorithm, the theoretical performance of a mechanical seal is often determined using the finite-difference method (FDM). However, compared with the finite-volume method (FVM) and finite-element method (FEM), FDM is weaker for dealing with the issue of discontinuous film thickness for a textured surface. In the present study, the thermo-hydrodynamic lubrication model of a mechanical seal is modified by means of an equivalent-thickness treatment, and the accuracy of the modified lubrication model is assessed by comparing its predictions for film pressure and temperature with published FVM and FEM results, showing that the equivalent-thickness lubrication model is effective for addressing the issue of discontinuous film thickness. The present work is important in that it improves the simulation accuracy of multi-objective optimization for textured mechanical seals.

scholarly journals Numerical and Experimental Study on Waviness Mechanical Seal of Reactor Coolant Pump

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1611
Author(s):  
Xiaodong Feng ◽  
Wentao Su ◽  
Yu Ma ◽  
Lei Wang ◽  
Heping Tan
Keyword(s):  
Liquid Film ◽  
Coupling Effect ◽  
Hydrodynamic Lubrication ◽  
Leakage Rate ◽  
Numerical Results ◽  
Force Balance ◽  
Mechanical Seal ◽  
Deformation Method ◽  
Coolant Pump ◽  
Reactor Coolant

Based on the fluid hydrodynamic lubrication theory, a mathematical model of liquid film lubrication was established for the waviness hydrodynamic mechanical seal of a reactor coolant pump. The influences of the waviness amplitude and pressure on the sealing performance were investigated by the numerical simulation. The numerical results showed that the leakage rate increases linearly as the pressure and waviness amplitude increase under the force balance condition. The minimum liquid film thickness decreases first and then increase as the pressure increases. Stationary slide rings with three different waviness amplitudes were processed using the pre-deformation method and tested at different pressure and temperature. The experiments showed that all the three kinds of seal have good stability under different pressure conditions. The experimental results showed that the leakage rate is influenced by the pressure, waviness amplitude, and temperature, and the leakage rate increases as the pressure increases. The comparison between experimental and numerical results showed that both the temperature and pressure affect the seal performance, and tends to a smaller leakage rate, which is quite different from the numerical values. Therefore, the multi-physics coupling effect should be considered in the numerical analysis of seal performance, and this will be studied in the further works.

A Hydrodynamic Theory of Radial-Face Mechanical Seals

1973 ◽  
Vol 15 (1) ◽  
pp. 17-24 ◽  
Author(s):  
B. Stanghan-Batch ◽  
E. H. Iny
Keyword(s):  
Experimental Evidence ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Fluid Pressure ◽  
Fluid Film ◽  
Hydrodynamic Theory ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Substantial Agreement ◽  
Seal Design

The existence of a lubricating fluid film between the faces of a mechanical seal has been amply demonstrated, but the mechanisms of lubrication and sealing have yet to be convincingly established. Experimental evidence to show that mechanical seal faces are most probably lubricated by a hydrodynamic action induced by the waviness of one of the surfaces has recently been published by the authors. Following this work a modified form of the narrow bearing approximation to Reynolds' equation for hydrodynamic lubrication has been applied to an idealized wavy faced seal. The resulting theory of seal face lubrication has been extended to include radial flows in the fluid film and predicts a net inward flow of fluid which may be utilized to oppose the flow due to the sealed fluid pressure. Predicted lubrication and sealing characteristics are in substantial agreement with measured values. It is suggested that the performance of mechanical seals can be improved by giving one face an appropriately wavy surface at the time of manufacture; a number of other observations on mechanical seal design are also made.

scholarly journals Two-scale homogenization of hydrodynamic lubrication in a mechanical seal with isotropic roughness based on the Elrod cavitation algorithm

2021 ◽  
pp. 135065012110176
Author(s):  
Yanxiang Han ◽  
Qingen Meng ◽  
Gregory de Boer
Keyword(s):  
Surface Topography ◽  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Tribological Performance ◽  
Stribeck Curve ◽  
Polar Coordinate System ◽  
Load Carrying Capacity ◽  
Mechanical Seal ◽  
Macro Scale ◽  
Load Carrying

A two-scale homogenization method for modelling the hydrodynamic lubrication of mechanical seals with isotropic roughness was developed and presented the influence of surface topography coupled into the lubricating domain. A linearization approach was derived to link the effects of surface topography across disparate scales. Solutions were calculated in a polar coordinate system derived based on the Elrod cavitation algorithm and were determined using homogenization of periodic simulations describing the lubrication of a series of surface topographical features. Solutions obtained for the hydrodynamic lubrication regime showed that the two-scale homogenization approach agreed well with lubrication theory in the case without topography. Varying topography amplitude demonstrated that the presence of surface topography improved tribological performance for a mechanical seal in terms of increasing load-carrying capacity and reducing friction coefficient in the radial direction. A Stribeck curve analysis was conducted, which indicated that including surface topography led to an increase in load-carrying capacity and a reduction in friction. A study of macro-scale surface waviness showed that the micro-scale variations observed were smaller in magnitude but cannot be obtained without the two-scale method and cause significant changes in the tribological performance.

Research on Feature Extraction Method Based on Rub-Impact Acoustic Emission Signals of Mechanical Seal End Faces

2010 ◽  
Vol 36 ◽  
pp. 68-74
Author(s):  
Chuan Jun Liao ◽  
Shuang Fu Suo ◽  
Wei Feng Huang
Keyword(s):  
Acoustic Emission ◽  
Feature Extraction ◽  
Extraction Methods ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Feature Extraction Method ◽  
Different Types ◽  
Ae Signal ◽  
Feature Information ◽  
Ae Signals

Acoustic emission (AE) techniques are put forward to monitor rub-impacts between rotating rings and stationary rings of mechanical seals by this paper. By analyzing feature extraction methods of the typical rub-impact AE signal, the method combining of wavelet scalogram and power spectrum is found useful, and can used to attribute the feature information implicated in rub-impact AE signals of mechanical seal end faces. Both simulations and experimental research prove that the method is effective, and are used successfully to identify the typical features of different types of rub-impacts of mechanical seal end faces.

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