TEHD Lubrication of Mechanical Face Seals in Stable Tracking Mode: Part 1—Numerical Model and Experiments

2003 ◽  
Vol 125 (3) ◽  
pp. 608-616 ◽  
Author(s):  
Noe¨l Brunetie`re ◽  
Bernard Tournerie ◽  
Jean Fre^ne
Keyword(s):  
Numerical Model ◽  
Thermal Behavior ◽  
Stokes Equations ◽  
Numerical Models ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Computer Code ◽  
Three Dimensional Model ◽  
Face Seals ◽  
Improved Model

After a short presentation of state-of-the-art experimental studies on the thermal behavior of non-contacting face seals, the literature about numerical models for thermal effects is investigated. Next, the geometry, kinematics and dynamics of a steady state three-dimensional model are developed. Simplified Navier-Stokes equations, a generalized Reynolds equation and an energy equation with proper boundary conditions are established for flow regimes, varying from laminar to turbulent. The numerical computer code for solving the governing equations is presented and representative results are shown. It is demonstrated that face distortions strongly modify the seals’ thermal behavior. An original test rig has been developed in order to ensure full fluid film conditions. This apparatus and the experimental procedure are described. The ability of the numerical model to simulate real configurations is also illustrated. Theoretical and experimental results are in good agreement. Yet an improved model of heat transfer on boundaries is still needed.

Numerical and Experimental Analysis of 3D Micro-Corrugated Wing in Gliding Flight

2021 ◽  
Author(s):  
Nasim Chitsaz ◽  
Kamran Siddiqui ◽  
Romeo Marian ◽  
Javaan S. Chahl
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Three Dimensional Model ◽  
Wing Model ◽  
Computational Fluid Dynamics Analysis ◽  
Gliding Flight ◽  
Flat Profile

Abstract In this study, computational fluid dynamics analysis was performed on a three-dimensional model of a Libellulidae wing to determine aerodynamic performance in gliding flight. The wing is comprised of various corrugated features alongside the spanwise and chordwise directions, as well as twist. The detailed features of real 3D dragonfly wing models, including all the corrugations through both span and chord, have not been considered in the past for a detailed aerodynamic analysis. The simulations were conducted by solving the Navier-Stokes equations to demonstrate gliding performance over a range of angles of attack at low Reynolds numbers. The numerical model was validated against experimental data obtained from a fabricated corrugated wing model using particle image velocimetry. The numerical results demonstrate that bio-inspired wings with corrugations compared to flat profile wings generate more lift with lower drag, trapping the vortices in the valleys of wing corrugation leading to delayed flow separation and delayed stall. The experimental and numerical results demonstrate that the methodology presented in this study can be used to measure bio-inspired 3D wing flow characteristics, including the influence of complex corrugations on aerodynamic performance. These findings contribute to the advancement of knowledge required for designing an optimized bioinspired micro air vehicle.

scholarly journals NUMERICAL MODEL OF 3D MORPHODYNAMIC AFTER OFFSHORE NOURISHMENT

2011 ◽  
Vol 1 (32) ◽  
pp. 55 ◽  
Author(s):  
Masamitsu Kuroiwa ◽  
Yoko Shibutani ◽  
Yuhei Matsubara ◽  
Takayuki Kuchiishi ◽  
Mazen Abualtyef
Keyword(s):  
Numerical Model ◽  
Diffusion Equation ◽  
Suspended Sediment Concentration ◽  
Three Dimensional ◽  
Sediment Concentration ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Sand Material

A three-dimensional model of morphodynamics after offshore nourishment was developed. In the presented model, the 3D beach evolution model that is not only after nourishment but also taking into account the nourishment process of injected sand material. In order to consider the injected process of sand, the computation using the advection-diffusion equation for suspended sediment concentration was adapted in the model. The presented model was applied to an idealized beach with two groins in order to investigate the performance of the model, and then, the model was applied to a field observation result for shoreface nourishment carried out at the Egmond aan Zee in the Netherlands. Finally, the applicability of the presented model was discussed from the computed results.

scholarly journals AERODYNAMICS OF JETS INTERACTING WITH A FLAT SURFACE

2019 ◽  
Vol 62 (4) ◽  
pp. 263-269
Author(s):  
I. A. Pribytkov ◽  
S. I. Kondrashenko
Keyword(s):  
Heat Transfer ◽  
Critical Point ◽  
Flat Surface ◽  
Stokes Equations ◽  
Thermal State ◽  
Exchange Process ◽  
Three Dimensional ◽  
Internal Diameter ◽  
Three Dimensional Model ◽  
Aerodynamic Properties

In this paper, the development features of a single free jet of hightemperature nitrogen interacting with a flat surface were studied. Calculation of the heat exchange process during heating by the attacking jets is very difficult to implement analytically due to complexity of the gas-dynamic processes occurring both in a single jet and in a system of jets interacting with the metal. The computational difficulties are aggravated by the fact that when interacting with the surface the jet as such disappears. The flat (fan) flow interacts with the surface: form, aerodynamic properties and thermal state of the flow strongly differ from those of the original jet. The studies were conducted on the basis of numerical simulation in the FloEFD software and computing complex for multiphysical simulation based on solution of the equations of gas dynamics and heat transfer. The solved system of equations consisted of Navier-Stokes equations, equations of energy and continuity and was supplemented by k – ε turbulence model. A three-dimensional model was developed for simulation, the necessary properties, initial and boundary conditions were specified. In the study of aerodynamics of a single high-temperature jet interacting with the surface, the main defining values were: nitrogen flow rate from the nozzle U0 , nitrogen temperature T, internal diameter of the nozzle d0 , distance from the nozzle section to the surface h, distance from the critical point (point of intersection of the jet axis with the surface) along the flow radius r. Data on the gas velocity decrease as the jet develops due to the loss of initial energy to engage the motionless surrounding gas in motion, is presented. The studies have shown that increase in the initial velocity of gas outflow brings the area of higher velocities closer to the surface both in the jet itself and in the fan jet. This factor contributes to heat transfer intensification. In addition, high speeds increase the total thickness of the fan flow and reduce the thickness of hydrodynamic boundary layer, which increases with distance from the critical point.

scholarly journals A numerical geotechnical model for computing soil slides at banks of water reservoirs

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nils Reidar B. Olsen ◽  
Stefan Haun
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Stokes Equations ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Field Measurements ◽  
Navier Stokes ◽  
Adaptive Grids ◽  
Groundwater Levels ◽  
Before And After

AbstractSoil slides can occur when the water level in a lake or a reservoir is lowered. This may take place in situations when a reservoir is flushed to remove sediments. The current study describes a three-dimensional numerical model used for the simulation of reservoir flushing that includes the slide movements. The geotechnical failure algorithms start with modelling the groundwater levels at the banks of the reservoir. A limit equilibrium approach is further used to find the location of the slides. The actual movement of the sediments is computed by assuming the soil to be a viscous liquid and by solving the Navier–Stokes equations. The resulting bed elevation changes from the slides are computed in adaptive grids that change as a function of water level, bed erosion and slide movements. The numerical model is tested on the Bodendorf reservoir in Austria, where field measurements are available of the bank elevations before and after a flushing operation. The results from the numerical simulations are compared with these observations. A parameter test shows that the results are very sensitive to the cohesion and less sensitive to the E and G modules of the soil.

Numerical Modelling of Circulation in Lake Sperillen, Norway

2000 ◽  
Vol 31 (1) ◽  
pp. 57-72 ◽  
Author(s):  
N. R. B. Olsen ◽  
D. K. Lysne
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Field Measurements ◽  
Navier Stokes ◽  
Water Current ◽  
Simple Method ◽  
Vertical Temperature Profile ◽  
Navier Stokes Equations ◽  
Good Agreement

A three-dimensional numerical model was used to model water circulation and spatial variation of temperature in Lake Sperillen in Norway. A winter situation was simulated, with thermal stratification and ice cover. The numerical model solved the Navier-Stokes equations on a 3D unstructured non-orthogonal grid with hexahedral cells. The SIMPLE method was used for the pressure coupling and the k-ε model was used to model turbulence, with a modification for density stratification due to the vertical temperature profile. The results were compared with field measurements of the temperature in the lake, indicating the location of the water current. Reasonably good agreement was found.

Application of Two Phase Eulerian CFD Model to Simulate High Velocity Jet Induced Scour

2020 ◽  
Author(s):  
Nicholas S. Tavouktsoglou ◽  
Aggelos Dimakopoulos ◽  
Jeremy Spearman ◽  
Richard J. S. Whitehouse
Keyword(s):  
Numerical Model ◽  
High Velocity ◽  
Stokes Equations ◽  
Solid Phase ◽  
Three Dimensional ◽  
Water Jet ◽  
Ocean Engineering ◽  
Two Phase ◽  
Water Jets ◽  
Good Agreement

Abstract Submerged water jet causing soil excavation is a typical water-soil interaction process that occurs widely in many engineering disciplines. In hydraulic engineering for instance, a typical example would be scour downstream of headcuts, culverts, or dam spillways. In port and waterway engineering, erosion of the channel bed or quay wall by the propellers of passing ships are also typical water jet/soil interaction problems. In ocean engineering, trenching by impinging high-velocity water jets has been used as an efficient method for cable and pipeline burial. At present, physical modelling and simple prediction equations have been the main practical engineering tool for evaluating scour in these situations. However, with the increasing computational power of modern computers and the development of new Computational Fluid Dynamics (CFD) solvers, scour prediction in such engineering problems has become possible. In the present work three-dimensional (3D) numerical modelling has been applied to reproduce the capability of a pair of water jets to backfill an excavated trench. The simulations are carried out using a state-of-the-art three-dimensional Eulerian two-phase scour model based on the open source CFD software OpenFOAM. The fluid phase is resolved by solving modified Navier-Stokes equations, which take into consideration the influence of the solid phase, i.e., the soil particles. This paper first presents a validation of the numerical model against vertical jet erosion tests from the literature and conducted at HR Wallingford. The results of the model show good agreement with the experimental tests, with the numerical model predicting the scour hole depth and extent with good accuracy. The paper then presents a validation of the model’s ability to reproduce deposition which is evaluated through a comparison with settling velocity data and empirical formulations found in literature, again with the model showing good agreement. Finally, the model is applied to a prototype cable burial problem using a commercially available controlled flow jet excavator. The study found that the use of water jets can be effective (subject to confirmation of the time-scale required for real operations) for performing backfill operations but that the effectiveness is closely related to the type of sediment and selection of an appropriate jet discharge. As a result, in order for the water jet method to be effective for backfill, there is a requirement for a good description of the variation in sediment type along the trench and a requirement for the jet discharge to be varied as different sediment types are encountered.

scholarly journals Hydrodynamic Effects Produced by Submerged Breakwaters in a Coastal Area with a Curvilinear Shoreline

2019 ◽  
Vol 7 (10) ◽  
pp. 337 ◽  
Author(s):  
Francesco Gallerano ◽  
Giovanni Cannata ◽  
Federica Palleschi
Keyword(s):  
Coastal Area ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Integral Form ◽  
Navier Stokes ◽  
Hydrodynamic Effect ◽  
Riemann Solver ◽  
Three Dimensional Model ◽  
Navier Stokes Equations

A three-dimensional numerical study of the hydrodynamic effect produced by a system of submerged breakwaters in a coastal area with a curvilinear shoreline is proposed. The three-dimensional model is based on an integral contravariant formulation of the Navier-Stokes equations in a time-dependent curvilinear coordinate system. The integral form of the contravariant Navier-Stokes equations is numerically integrated by a finite-volume shock-capturing scheme which uses Monotonic Upwind Scheme for Conservation Laws Total Variation Diminishing (MUSCL-TVD) reconstructions and an Harten Lax van Leer Riemann solver (HLL Riemann solver). The numerical model is used to verify whether the presence of a submerged coastal defence structure, in the coastal area with a curvilinear shoreline, is able to modify the wave induced circulation pattern and the hydrodynamic conditions from erosive to accretive.

Numerical Model of Three-Dimensional Motion of Plate-Type Wind-Borne Debris Based on Quaternions and its Improvement in Unsteady Flow

2013 ◽  
Vol 405-408 ◽  
pp. 2399-2408 ◽  
Author(s):  
An Min Fu ◽  
Peng Huang ◽  
Ming Gu
Keyword(s):  
Numerical Model ◽  
Unsteady Flow ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Moment Coefficient ◽  
Flight Mode ◽  
Gimbal Lock ◽  
Improved Model ◽  
Plate Type ◽  
Good Agreement

A numerical model of three-dimensional motion of plate-type wind-borne debris in uniform wind field based on quaternions is proposed in this paper. This model can simulate the complex 3D spinning flight robustly and efficiently with rotational quaternions, which are also free from the gimbal lock that is associated with Euler rotational matrix. The predictions from the model were then compared with the results of another quasi-steady model, and good agreement is found. For the unsteady flow involved in autorotational flight mode, the present model was improved by revising the damping moment in order to simulate the two-dimensional motion of plates with higher accuracy. Calibration of the damping moment coefficient was performed through a direct comparison of the predicted non-dimensional angular velocity with the results of CFD-RBD model. The predictions of the improved model agree reasonably well with the CFD-RBD results, which verifies the accuracy of the improved model in predicting the two-dimensional trajectories of plates.

Effect of Blade Numbers on Pressure Drop of Axial Cyclone Separators by CFD

2011 ◽  
Vol 55-57 ◽  
pp. 343-347 ◽  
Author(s):  
Yi Gang Luan ◽  
Hai Ou Sun
Keyword(s):  
Pressure Drop ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Three Dimensional Model ◽  
Navier Stokes Equations ◽  
Pressure Drops ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Resistance Performance

In this article, computational fluid dynamics(CFD) method is used to predict the effect of blade numbers on the pressure drop of axial cyclone separators. A three-dimensional model is built to acquire the resistance of axial cyclone separators with different blade numbers. The flow field inside cyclone separators is calculated using 3D Reynolds-averaged Navier-Stokes equations. And turbulence model is used to simulate the Reynold stress. Also pressure drop of cyclone separators with different blade numbers is expressed as a function of different inlet velocities. At the same inlet velocity with increasing the blade numbers, pressure drops of cyclones reduce greatly. And changing the blade number of cyclone separator is an effective method to improve its resistance performance.

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