scholarly journals Experimental and numerical study of wavy mechanical face seals operating under pressure inversions

2019 ◽  
Vol 234 (2) ◽  
pp. 247-260 ◽  
Author(s):  
Jérémy Cochain ◽  
Noël Brunetière ◽  
Andrew Parry ◽  
Henri Denoix ◽  
Abdelghani Maoui
Keyword(s):  
Numerical Model ◽  
Numerical Study ◽  
Hydrodynamic Pressure ◽  
Poor Performance ◽  
Force Balance ◽  
Face Seal ◽  
Spring Force ◽  
Face Seals ◽  
The Face ◽  
The Impact

This paper investigates the impact of the face waviness and pressure inversions on the leakage and on the outer fluid entry of mechanical face seals using a numerical model and an experimental setup. The numerical model couples a transient Reynolds equation, an analytical contact model, a force balance solver, and a solver for the thermo-mechanical deformations. The experimental tests on a face seal with low waviness and on a face seal with high waviness provide leakage and outer fluid entry data, which are reproduced by the model. Contrary to the face seal with low waviness, the face seal with high waviness has poor performance and the pressure inversions increase significantly the ingression of outer fluid. The parametric study shows a decrease of leakage with increasing spring force, and an increase of leakage and outer fluid entry with increasing values of waviness amplitude. The higher leakage observed for wavy seals is shown to be due to the higher average film thickness, and to some extent due to the mechanisms associated with waviness: hydrodynamic pressure generation, film squeeze and stretching.

Numerical Analysis of Dry Gas Face Seals With Spiral Groove and Inner Annular Groove

2008 ◽  
Author(s):  
Xu-Dong Peng ◽  
Li-Li Tan ◽  
Ji-Yun Li ◽  
Song-En Sheng ◽  
Shao-Xian Bai
Keyword(s):  
Reynolds Equation ◽  
Geometric Parameters ◽  
Axial Stiffness ◽  
Face Seal ◽  
Optimization Principle ◽  
Face Seals ◽  
The Face ◽  
Gas Face Seal ◽  
Film Stiffness ◽  
Spiral Grooves

A two-dimensional Reynolds equation was established for isothermal compressible gas between the two faces of a dry gas face seal with both spiral grooves and an inner annular groove onto the hard face. The opening force, the leakage rate, the axial film stiffness and the film stiffness to leakage ratio were calculated by finite element method. The comparisons with the sealing performances of a typical gas face seal only with spiral grooves onto its hard face were made. The effects of the face geometric parameters on the static behavior of such a seal were analyzed. The optimization principle for geometric parameters of a dry gas face seals with spiral grooves and an inner annular groove was presented. The recommended geometric parameters of spiral grooves and circular groove presented by optimization can ensure larger axial stiffness while lower leakage rates.

Experimental and Numerical Study of Ballistic Impact Performance on UHMWPE Composites

2013 ◽  
Vol 818 ◽  
pp. 30-36 ◽  
Author(s):  
Yao Ke Wen ◽  
Cheng Xu ◽  
Ai Jun Chen ◽  
Shu Wang
Keyword(s):  
Numerical Model ◽  
Composite Plate ◽  
Numerical Study ◽  
Von Mises Stress ◽  
High Speed Photography ◽  
Numerical Predictions ◽  
Back Face ◽  
Uhmwpe Composites ◽  
The Impact ◽  
Bulge Height

A series of ballistic tests were performed to investigate the bulletproof performance of UHMWPE composites. The temporal evolution of the UHMWPE composite plate back-face bulge height and diameter were captured by high-speed photography. The experiments show the composite plate were perforated when the impact velocity greater than 880m/s. The maximum bulge height and diameter can reach to 3.63-8.23mm and 37-64.5mm at the experimental velocity range , respectively. After that, the numerical model was built with composite material model MAT59 in LS-DYNA and stress based contact failure between plies were adopted to model the delamination mechanism. The number of plies of numerical model shows a strong dependency on the numerical results. Comparisons between numerical predictions and experimental results in terms of bulge height and diameter are presented and discussed. The maximum bulge diameter is good agreement with experiment, but the computational results under predict the maximum bulge height. The computational analysis show the damage development of the plate penetration by the projectile is shearing dominated at first, then the plate undergoes delamination and stretching in the later part of the impact process. The von mises stress at front and back face of the plate were also studied.

THE IMPACT OF SELECTED PARAMETERS ON PRESSURE DISTRIBUTION IN THE FACE THROTTLE OF A CENTRIFUGAL PUMP AUTOMATIC BALANCING DEVICE

Tribologia ◽  
2021 ◽  
Vol 297 (3) ◽  
pp. 35-44
Author(s):  
Yuliia Tarasevych ◽  
Nataliia SOVENKO
Keyword(s):  
Fluid Flow ◽  
Pressure Distribution ◽  
Hydrodynamic Pressure ◽  
Centrifugal Pumps ◽  
Unsteady Fluid Flow ◽  
The Face ◽  
Unsteady Fluid ◽  
Angular Displacements ◽  
Automatic Balancing ◽  
The Impact

Face throttles are a necessary functional element of non-contact face seals and automatic balancing devices of centrifugal pumps of different constructions. To calculate the hydrodynamic forces and moments acting on the rotor and fluid flow through the automatic balancing device, it is necessary to know the pressure distribution in the cylindrical and face throttle when considering all important factors which predetermine fluid flow. The face throttle surfaces are moving, which leads to unsteady fluid flow. The movement of the walls of the face throttle causes an additional circumferential and radial flow, which subsequently leads to the additional hydrodynamic pressure components. The paper analyses viscous incompressible fluid flow in the face throttle of an automatic balancing device taking into account the axial and angular displacements of throttle’s surfaces and the inertia component of the fluid. The effect of local hydraulic losses as well as random changes in the coefficients of local hydraulic resistance at the inlet and outlet of the throttle is analysed.

Numerical Study of Basalt Fibre Cloth Strengthened Structural Insulated Panel under Windborne Debris Impact

2016 ◽  
Vol 846 ◽  
pp. 446-451 ◽  
Author(s):  
Qing Fei Meng ◽  
Hong Hao ◽  
Wen Su Chen
Keyword(s):  
Numerical Model ◽  
Structural Damage ◽  
Numerical Study ◽  
Building Envelope ◽  
Basalt Fibre ◽  
Structural Wall ◽  
Windborne Debris ◽  
Strong Winds ◽  
The Impact ◽  
Debris Impact

Strong winds happen around the world every year and cause enormous damages and losses. Besides large wind pressure, impact from windborne debris on building envelope is a major source of structural damage in strong winds. The debris lifted and carried by wind impacting on building envelop may create openings on building envelope which increase internal pressure of the building, and lead to roof lifting and even total building collapse. Preventing impact damage to structural wall and roof is therefore critical in extreme wind conditions. On the other hand Structural Insulated Panel (SIP) with Oriented Strand Board (OSB) skins is popularly used in the building industry. Previous studies revealed that such SIP panels had weak impact resistant capacity and do not meet the design requirements to resist windborne debris impact specified in Australian Standard (AS/NZS1170.2:2011) for their applications in cyclonic regions. To increase the capacity of such SIP panels against windborne debris impact, basalt fibre cloth was used to strengthen the panel. Laboratory tests found that SIP strengthened with basalt fibre cloth was effective in increasing its impact-resistant capacity. This paper presents the development of a reliable numerical model to predict the impact responses of basalt fibre cloth strengthened SIP panel in LS-DYNA. The accuracy of the numerical model is verified by comparing the numerical and experimental results. The validated numerical model provides a reliable tool to predict basalt fibre cloth strengthened SIPs.

Numerical study of the melting and resolidification of the substrate during the impact of a ceramic droplet in a plasma spraying process

2019 ◽  
Vol 88 (2) ◽  
pp. 20901 ◽  
Author(s):  
Mouloud Driouche ◽  
Tahar Rezoug ◽  
Mohammed El Ganaoui
Keyword(s):  
Numerical Model ◽  
Phase Change ◽  
Solid Phase ◽  
Numerical Study ◽  
Solid Substrate ◽  
Navier Stokes ◽  
Droplet Spreading ◽  
Substrate Melting ◽  
Volume Method ◽  
The Impact

The substrate melting can significantly improve the properties of plasma spray coatings. Indeed the adhesion of the projected particles to the substrate can be ameliorated by the substrate melting. In this article, a numerical model is developed to study the dynamics of fluids and heat transfer with liquid/solid phase change during impact of a fully melted alumina particle on an aluminum solid substrate, taking into account of the substrate melting. The model is based on solving the Navier-Stokes and energy equations with liquid / solid phase change. These equations are coupled with the fluid of volume method (VOF), to follow the free surface of the particle during its spreading and solidification. The finite volume method is used to discretize the equations in a 2D axisymmetric domain. A comparison with the published experimental results was carried out to validate this numerical model. Simulations were performed for different initial droplet diameters to study its effect on droplet spreading as well as on substrate melting. It has been observed that the substrate melting begins before the droplet spreads completely; the substrate melting reaches its maximum when the droplet is close to its total solidification. Droplet spreading and substrate melting are more important for large sizes droplets.

scholarly journals Bench Set Impact Analysis on Fail-Safe Condition of Fail to Closed Type Control Valve with Spring-Diaphragm Actuator

2020 ◽  
Vol 2 (1) ◽  
pp. 11-14
Author(s):  
Yoki Andriawan Ramdan ◽  
Dena Hendriana ◽  
Henry Nasution ◽  
Gembong Baskoro
Keyword(s):  
Impact Analysis ◽  
Control Valve ◽  
Force Balance ◽  
Critical Parameters ◽  
Permissible Range ◽  
Spring Force ◽  
Valve Opening ◽  
Safe Condition ◽  
Fail Safe ◽  
The Impact

Control valve is one of key elements in processing of a chemical industry and it is one of its important functions is as a flow control of chemical process. The accuracy of control valve opening or traveling is proportional to flow capacity. On the other hand, a leakage of a control valve on its failed position especially for Air to Open-Fail Closed (ATO-FC) type valve can become a disaster. One of critical parameters in Control Valve that impacts to performance and fail-safe position is Bench set range spring in valve’s actuator. This work analyzed this Bench set range impact to the fail-safe position. The force in spring is defined by control valve specification verified by force balance method of control valve. Then the impact of bench set range was analyzed by displacement of spring from spring force equation. At the end, the outcome is displacement data in correlation to the change of bench set range. It helps the repair technician on the maintenance workshop of permissible range when they adjust the bench set range by adjusting spring compression.

The effect of the thermal plume generated by body heat dissipation on the containment of fume hood

2020 ◽  
pp. 1420326X2097473
Author(s):  
Dong Liu ◽  
Chuang Meng ◽  
Jiaxin Chen ◽  
Lirong Li
Keyword(s):  
Numerical Model ◽  
Heat Dissipation ◽  
Thermal Plume ◽  
Breathing Zone ◽  
Fume Hood ◽  
The Face ◽  
Face Velocity ◽  
Volume Method ◽  
The Impact ◽  
Body Heat

The impact of human body heat dissipation on the containment of a fume hood was conducted via experiments and numerical model. The experiments evaluated hood face velocity and the temperature around the mannequin; the results validated the simulation. The numerical model was based on the governing equations of fluid flow via the finite volume method. The face velocities (0.3–0.9 m·s− 1 ) and temperature differences (11°C, 8°C and 5°C) between the surface of the mannequin and its surroundings were used as variables. The numerical results show that in addition to the blockage effect of the worker standing in front of the fume hood, there is a more important thermal effect on the containment of fume hood. The thermal plume carries pollutants leaking out of the hood face to the breathing zone. The face velocity and dimensionless value (Gr/Re 2 ) are recommended to be 0.4–0.6 m·s− 1 and 20–35 respectively, to reduce the influence of human thermal plume on the containment of fume hood and energy waste. The formula related to the rising distance of thermal plume, Grashof and Reynolds numbers (Gr/Re 2 ) was determined.

Numerical Study of Wave-Driven Impact of a Sea Ice Floe on a Circular Cylinder

2016 ◽  
Author(s):  
Biao Su ◽  
Karl Gunnar Aarsæther ◽  
David Kristiansen
Keyword(s):  
Numerical Model ◽  
Circular Cylinder ◽  
Sea Ice ◽  
Numerical Study ◽  
Offshore Structures ◽  
Experimental Result ◽  
Recent Experimental Study ◽  
Pressure Area ◽  
Closed Form Analytical Solution ◽  
The Impact

This paper presents a numerical model for simulating wave-driven ice floe–structure interactions, which is integrated in a software framework (FhSim) for time-domain simulation of marine systems. The FhSim framework has proved to be a valuable tool for research and development within different applications and areas [1]. In this study, the wave-driven impact of a sea ice floe on a circular cylinder is simulated. The simulation setup refers to a recent experimental study [2], and the kinematics of ice floe in wave is compared with the experimental result. As the impact forces were not measured in the experiment, a closed-form analytical solution proposed by ISO/FDIS 19906 (Arctic offshore structures) is used for comparison. These comparisons indicate that the present numerical model is able to reproduce the ice floe kinematics and impact characteristics during floe–structure interaction. Furthermore, a sensitivity analysis is conducted, aimed at investigating how much the simulated impact force is affected by variations in the pressure–area relationship.

scholarly journals Reduction of tsunami inundation by coastal forests in Yogyakarta, Indonesia: a numerical study

2012 ◽  
Vol 12 (1) ◽  
pp. 85-95 ◽  
Author(s):  
W. Ohira ◽  
K. Honda ◽  
K. Harada
Keyword(s):  
Numerical Model ◽  
Numerical Study ◽  
Exponential Model ◽  
Coastal Areas ◽  
Coastal Forest ◽  
Coastal Forests ◽  
Tsunami Inundation ◽  
Inundation Depth ◽  
Damping Effects ◽  
The Impact

Abstract. Coastal forests are known to protect coastal areas from environmental degradation. In this paper, we examined another important role of coastal forests – to mitigate tsunami devastations to coastal areas. Using a two-dimensional numerical model (Harada and Imamura model, 2005), we evaluated the damping effects of a coastal forest to resist tsunami inundation in Yogyakarta, Indonesia. In the simulations, we set up a two-km long control forest with a representative topography of the study site and experimented its damping performance sensitivity under various width configurations, e.g. 20, 40, 60, 80, 100 and 200 m. The initial tsunami wave was set such that the inundation depth at the front edge of the forest would not exceed 4 m (tree fragility limit). The forest variables such as species, density, DBH, height and canopy size were determined from a typical forest of the site (Casuarina plantation, 4 trees/100 m2, Diameter at Breast Height = 0.20 m). The results showed that coastal forest with 100 m width reduced inundation flux, depth and area by 17.6, 7.0 and 5.7%, respectively. Exponential models were found to describe the relationships between forest width and tsunami inundation transmission. An additional experiment was performed using actual topography and a forest plantation plan with 100 m width for 2.46 km2. In this experiment, the results showed that the plan would reduce inundation flux by 10.1%, while the exponential model estimated it to be 10.6%, close to the numerical model results. It suggests that statistical models of forest width and damping effects are useful tools for plantation planning, as it allows for quicker evaluation of the impact of coastal forest without simulation modeling that requires a lot of data, time and computing power.

A closed-form contact model for gas face seals during the opened operation

2018 ◽  
Vol 70 (6) ◽  
pp. 1110-1118 ◽  
Author(s):  
Songtao Hu ◽  
Noel Brunetiere ◽  
Weifeng Huang ◽  
Xi Shi ◽  
Zhike Peng ◽  
...  
Keyword(s):  
Closed Form ◽  
Rotor Dynamics ◽  
Contact Model ◽  
Strong Impact ◽  
Face Seal ◽  
Content Type ◽  
Face Seals ◽  
The Face ◽  
Nonparallel Plane ◽  
Gas Face Seal

Purpose Face contact has a strong impact on the service life of non-contacting gas face seals; the current research which mainly focuses on the face contact had appeared during the startup or shutdown operation. This paper aims to present a closed-form contact model of a gas face seal during the opened operation. Design/methodology/approach Referring to the axial rub-impact model of rotor dynamics, a closed-form contact model is developed under a nonparallel plane contact condition that corresponds to the local face contact of sealing rings arising from some disturbances during the opened operation. The closed-form contact model and a direct numerical contact model are performed on Gaussian surfaces to compare the contact behavior. Findings The closed-form contact model is in a good agreement with the direct numerical contact model. However, the closed-form contact model cannot involve the influence of grooves on the sealing ends. The error is eliminated in some other types of gas face seals such as coned gas face seals. Besides non-contacting face seals, the closed-form model can be applied to the axial rub impact of rotor dynamics. Originality value A closed-form contact model of a gas face seal is established during the opened operation. The closed-form contact model is validated by a direct numerical contact model. The closed-form contact model also suits for axial rub-impact of rotor dynamics.

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