Enhanced understanding of leakage in mechanical seals with elliptical dimples based on CFD simulation

2019 ◽  
Vol 72 (1) ◽  
pp. 24-30
Author(s):  
Sen Jiang ◽  
Hua Ji ◽  
Tianhao Wang ◽  
Donglin Feng ◽  
Qian Li
Keyword(s):  
Cfd Simulation ◽  
Three Dimensional ◽  
Leakage Rate ◽  
Geometric Feature ◽  
Maximum Pressure ◽  
Mechanical Seals ◽  
Ansys Fluent ◽  
Content Type ◽  
Surface Textures ◽  
Influencing Mechanism

Purpose The shapes of surface textures have been designed to control the leakage of mechanical seals in recent years. The purpose of this paper is to demonstrate the influence of geometric properties of elliptical dimples on the leakage rate. Design/methodology/approach A new geometric feature point is expressed using an analytical solution to locate the high-pressure zones. Furthermore, a numerical model of the three-dimensional flow field for the mechanical seal with elliptical dimples is developed using ANSYS Fluent to demonstrate the influencing mechanism. Findings The location of the proposed geometric converging point coincides with the maximum pressure point under different orientation angles. An inward flow on the leakage section observed from the simulation results is responsible for decreasing the leakage rate. Originality/value The influencing mechanism of the elliptical dimple on the leakage rate is demonstrated, which can facilitate the design of surface textures.

scholarly journals Analysis of Pressure Transient Following Rapid Filling of a Vented Horizontal Pipe

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1698 ◽  
Author(s):  
Lin Li ◽  
David Zhu ◽  
Biao Huang
Keyword(s):  
Three Dimensional ◽  
Pressure Oscillation ◽  
Approximate Solutions ◽  
Periodic Wave ◽  
Oscillation Period ◽  
Maximum Pressure ◽  
Ansys Fluent ◽  
Horizontal Pipe ◽  
Sinusoidal Motion ◽  
Short Period

Rapid filling/emptying of pipes is commonly encountered in water supply and sewer systems, during which pressure transients may cause unexpected large pressure and/or geyser events. In the present study, a linearized analytical model is first developed to obtain the approximate solutions of the maximum pressure and the characteristics of pressure oscillations caused by the pressurization of trapped air in a horizontal pipe when there is no or insignificant air release. The pressure pattern is a typical periodic wave, analogous to sinusoidal motion. The oscillation period and the time when the pressure attains the peak value are significantly influenced by the driving pressure and the initial length of the entrapped air pocket. When there is air release through a venting orifice, analysis by a three-dimensional computational fluid dynamics model using ANSYS Fluent was also conducted to furnish insights and details of air–water interactions. Flow features associated with the pressurization and air release were examined, and an air–water interface deformation that one-dimensional models are incapable of predicating was presented. Modelling results indicate that the residual air in the system depends on the relative position of the venting orifice. There are mainly two types of pressure oscillation patterns: namely, long or short-period oscillations and waterhammer. The latter can be observed when the venting orifice is located near the end of the pipe where the air is trapped.

scholarly journals The Numerical Diffusion Effect on the CFD Simulation Accuracy of Velocity and Temperature Field for the Application of Sustainable Architecture Methodology

2020 ◽  
Vol 12 (23) ◽  
pp. 10173
Author(s):  
Vladimíra Michalcová ◽  
Kamila Kotrasová
Keyword(s):  
Temperature Field ◽  
Cfd Simulation ◽  
Flow Direction ◽  
Three Dimensional ◽  
Stationary Flow ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Simulation Accuracy ◽  
Numerical Diffusion ◽  
Diffusion Temperature

Numerical simulation of fluid flow and heat or mass transfer phenomenon requires numerical solution of Navier–Stokes and energy-conservation equations, together with the continuity equation. The basic problem of solving general transport equations by the Finite Volume Method (FVM) is the exact calculation of the transport quantity. Numerical or false diffusion is a phenomenon of inserting errors in calculations that threaten the accuracy of the computational solution. The paper compares the physical accuracy of the calculation in the Computational Fluid Dynamics (CFD) code in Ansys Fluent using the offered discretization calculation schemes, methods of solving the gradients of the transport quantity on the cell walls, and the influence of the mesh type. The paper offers possibilities on how to reduce numerical errors. In the calculation area, the sharp boundary of two areas with different temperatures is created in the flow direction. The three-dimensional (3D) stationary flow of the fictitious gas is simulated using FVM so that only advective transfer, in terms of momentum and heat, arises. The subject of the study is to determine the level of numerical diffusion (temperature field scattering) and to evaluate the values of the transport quantity (temperature), which are outside the range of specified boundary conditions at variously set calculation parameters.

The simulation of single wraparound fin on a semi-cylindrical missile body

2020 ◽  
Vol 92 (3) ◽  
pp. 418-427 ◽  
Author(s):  
Nayhel Sharma ◽  
Rakesh Kumar
Keyword(s):  
Research Study ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Future Research ◽  
Aerodynamic Coefficients ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Predicted Values ◽  
Characteristic Trend ◽  
Practical Implications

Purpose The purpose of this paper is to establish a freestream computational fluid dynamics (CFD) model of a three-dimensional non-spinning semi-cylindrical missile model with a single wrap around fin in Mach 2.70-3.00M range and 0° angle of attack, and ultimately establishing itself for future research study. Design/methodology/approach In this study, the behaviour of flow around the fin was investigated using a κ-ϵ turbulence model of second-order of discretization. This was done using a highly structured mesh. Additionally, an inviscid CFD simulation involving the same boundary conditions have also been carried out for comparison. Findings The obtained values of aerodynamic coefficients and pressure contours visualizations are compared against their experimental and computational counterparts. A typical missile aerodynamic characteristic trend can be seen in the current CFD. Practical implications The predicted values of the aerodynamic coefficients of this single fin model have also been compared to those of the full missile body comprising of four fins from the previous research studies, and a similar aerodynamic trend can be seen. Originality/value This study explores the possibility of the use of turbulence modelling in a single fin model of a missile and provides a basic computational model for further understanding the flow behaviour near the fin.

RBF-based mesh morphing approach to perform icing simulations in the aviation sector

2019 ◽  
Vol 91 (4) ◽  
pp. 620-633 ◽  
Author(s):  
Corrado Groth ◽  
Emiliano Costa ◽  
Marco Evangelos Biancolini
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Ansys Fluent ◽  
Content Type ◽  
Mesh Morphing ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses ◽  
2D And 3D ◽  
First Time ◽  
Practical Implications

Purpose Numerical simulation of icing has become a standard. Once the iced shape is known, however, the analyst needs to update the computational fluid dynamics (CFD) grid. This paper aims to propose a method to update the numerical mesh with ice profiles. Design/methodology/approach The present paper concerns a novel and fast radial basis functions (RBF) mesh morphing technique to efficiently and accurately perform ice accretion simulations on industrial models in the aviation sector. This method can be linked to CFD analyses to dynamically reproduce the ice growth. Findings To verify the consistency of the proposed approach, one of the most challenging ice profile selected in the LEWICE manual was replicated and simulated through CFD. To showcase the effectiveness of this technique, predefined ice profiles were automatically applied on two-dimensional (2D) and three-dimensional (3D) cases using both commercial and open-source CFD solvers. Practical implications If ice accreted shapes are available, the meshless characteristic of the proposed approach enables its coupling with the CFD solvers currently supported by the RBF4AERO platform including OpenFOAM, SU2 and ANSYS Fluent. The advantages provided by the use of RBF are the high performance and reliability, due to the fast application of mesh smoothing and the accuracy in controlling surface mesh nodes. Originality/value As far as authors’ knowledge is concerned, this is the first time in scientific literature that RBF are proposed to handle icing simulations. Due to the meshless characteristic of the RBF mesh morphing, the proposed approach is cross solver and can be used for both 2D and 3D geometries.

Experimental verification of textured mechanical seal designed using multi-objective optimization

2019 ◽  
Vol 71 (6) ◽  
pp. 766-771 ◽  
Author(s):  
Xiuying Wang ◽  
Michael Khonsari ◽  
Siyuan Li ◽  
Qingwen Dai ◽  
Xiaolei Wang
Keyword(s):  
Leakage Rate ◽  
Free Form ◽  
Optimization Approach ◽  
Multi Objective Optimization ◽  
Mechanical Seals ◽  
Content Type ◽  
Multi Objective ◽  
Load Carrying ◽  
And Control ◽  
Good Agreement

Purpose This study aims to simultaneously enhance the load-carrying capacity and control the leakage rate of mechanical seals by optimizing the texture shape. Design/methodology/approach A multi-objective optimization approach is implemented to determine the optimal “free-form” textures and optimal circular dimples. Experiments are conducted to validate the simulation results. Findings The experimental coefficient of friction (COF) and leakage rate are in good agreement with the calculated results. In addition, the optimal “free-form” texture shows a lower COF and a lower leakage in most cases. Originality/value This work provides a method to optimize the surface texture for a better combination performance of mechanical seals.

Simulation of eutectic plates in medium refrigerated transport

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Thandiwe Bongani Radebe ◽  
Zhongjie Huan ◽  
Jeffrey Baloyi
Keyword(s):  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Primary Energy ◽  
Cold Chain ◽  
Eutectic System ◽  
Ansys Fluent ◽  
Content Type ◽  
Refrigerated Transport ◽  
Transport Vehicle ◽  
Airflow Condition

Purpose South Africa is the highest consumer of commercial energy per capita in Africa, ranking 16th in the world for primary energy consumption. It is also ranked among the bottom 50 of the 150 countries regarding energy efficiency. The cold chain is a large contributor through refrigerated transport vehicles. To comply with the changing climate regulations, cryogenic and eutectic systems are systems with great potential for small distance refrigerated transport. The purpose of this paper is to introduce eutectic system to medium distance refrigerated transport. Design/methodology/approach This study presents the potential use of Eutectic plates inside a medium refrigerated transport vehicle, by numerically investigating the characteristics of phase change material eutectic plates applied at low-temperature ranges. A physical model and a mathematical model for three-dimensional transient natural flow were developed as proposed by Xiaofeng and Zhang. Using the governing equation of mass, momentum and energy conservation, three Eutectic plate configurations were modeled and simulated in ANSYS Fluent for 5 h. Findings A uniform heat transfer and airflow condition inside a refrigerated compartment were predicted using the Reynolds stress model. The configuration with eutectic plates placed at the top and side showed great potential for the system functioning in the South African climate. Research limitations/implications Medium refrigerated transport vehicle. Originality/value This configuration had a high-temperature distribution across the compartment and promoted high air circulations, showing that it could be ideal for medium refrigerated transport vehicles delivering perishable foodstuffs or non-food goods.

Comparing ANSYS Fluent® and OpenFOAM® simulations of Geldart A, B and D bubbling fluidized bed hydrodynamics

2019 ◽  
Vol 30 (1) ◽  
pp. 93-118 ◽  
Author(s):  
Cesar Martin Venier ◽  
Andrés Reyes Urrutia ◽  
Juan Pablo Capossio ◽  
Jan Baeyens ◽  
Germán Mazza
Keyword(s):  
Fluidized Bed ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Internal Diameter ◽  
Ansys Fluent ◽  
Content Type ◽  
Current State ◽  
Bubbling Fluidized Bed ◽  
Bubble Sizes

Purpose The purpose of this study is to assess the performance of ANSYS Fluent® and OpenFOAM®, at their current state of development, to study the relevant bubbling fluidized bed (BFB) characteristics with Geldart A, B and D particles. Design/methodology/approach For typical Geldart B and D particles, both a three-dimensional cylindrical and a pseudo-two-dimensional arrangement were used to measure the bed pressure drop and solids volume fraction, the latter by digital image analysis techniques. For a typical Geldart A particle, specifically to examine bubbling and slugging phenomena, a 2 m high three-dimensional cylindrical arrangement of small internal diameter was used. The hydrodynamics of the experimentally investigated BFB cases were also simulated for identical geometries and operating conditions using OpenFOAM® v6.0 and ANSYS Fluent® v19.2 at identical mesh and numerical setups. Findings The comparison between experimental and simulated results showed that both ANSYS Fluent® and OpenFOAM® provide a fair qualitative prediction of the bubble sizes and solids fraction for freely-bubbling Geldart B and D particles. For Geldart A particles, operated in a slugging mode, the qualitative predictions are again quite fair, but numerical values of relevant slug characteristics (length, velocity and frequency) slightly favor the use of OpenFOAM®, despite some deviations of predicted slug velocities. Originality/value A useful comparison of computational fluid dynamics (CFD) software performance for different fluidized regimes is presented. The results are discussed and recommendations are formulated for the selection of the CFD software and models involved.

Acoustic Analysis of Condenser Fan of Split Air Conditioner Using Numerical and Experimental Method

2015 ◽  
Vol 23 (02) ◽  
pp. 1550012 ◽  
Author(s):  
Nitin Gulhane ◽  
Sandip Patil ◽  
Kanwaljeet Singh
Keyword(s):  
Cfd Simulation ◽  
Acoustic Analysis ◽  
Three Dimensional ◽  
Axial Flow ◽  
Accurate Method ◽  
Experimental Result ◽  
Optimized Design ◽  
Air Conditioner ◽  
Ansys Fluent ◽  
Fan Blade

The present work aims to investigate the accurate method of performing computational fluid dynamics (CFD) — Acoustic analysis for axial flow fans in split air conditioner system. A comprehensive simulation procedure is developed to predict flow-induced noise in a system. The three-dimensional domain using k–ε turbulence model and Ffowcs Williams and Hawkings (FW-H) acoustic model is considered to predict noise generated by the fan blade surface. The acoustic and flow performances of the fan are predicted simultaneously using a computational aero-acoustic technique (combining steady flow and noise propagation analysis). The different cases are simulated by varying the blade angle, blade depth, blade width and serrations at trailing edge of fan blade. An impact of each of these parameter on A-weighted sound pressure level (SPL) and mass flow rate at outlet is determined. The numeric value of obtained A-weighted SPL by CFD simulation is found to be in close agreement with the experimental result within 5.4%. Finally, above mentioned parameters are varied in simulation and optimized design is proposed based on A-weighted SPL and cubic feet per minute (CFM). All simulations are carried out in commercially available CFD solver; ANSYS FLUENT 13.

scholarly journals Computational Methodology for Knocking Combustion Analysis in Compression-Ignited Advanced Concepts

2018 ◽  
Vol 8 (10) ◽  
pp. 1707 ◽  
Author(s):  
José Serrano ◽  
Ricardo Novella ◽  
Josep Gomez-Soriano ◽  
Pablo Martinez-Hernandiz
Keyword(s):  
Cfd Simulation ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Navier Stokes ◽  
Maximum Pressure ◽  
Engine Operation ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Operation Results

In the present work, a numerical methodology based on three-dimensional (3D) computational fluid dynamics (CFD) was developed to predict knock in a 2-Stroke engine operating with gasoline Partially Premixed Combustion (PPC) concept. Single-cycle Unsteady Reynolds-Averaged Navier Stokes (URANS) simulations using the renormalization group (RNG) k − ε model were performed in parallel while the initial conditions are accordingly perturbed in order to imitate the variability in the in-cylinder conditions due to engine operation. Results showed a good agreement between experiment and CFD simulation with respect to cycle-averaged and deviation of the ignition timing, combustion phasing, peak pressure magnitude and location. Moreover, the numerical method was also demonstrated to be capable of predicting knock features, such as maximum pressure rise rate and knock intensity, with good accuracy. Finally, the CFD solution allowed to give more insight about in-cylinder processes that lead to the knocking combustion and its subsequent effects.

Generalized periodic surface model and its application in designing fibrous porous media

2015 ◽  
Vol 32 (1) ◽  
pp. 7-36 ◽  
Author(s):  
Wei Huang ◽  
Sima Didari ◽  
Yan Wang ◽  
Tequila A.L. Harris
Keyword(s):  
Porous Media ◽  
Geometric Modeling ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Field Method ◽  
Surface Model ◽  
Periodic Surface ◽  
Content Type ◽  
Modeling Methods ◽  
Fibrous Porous Media

Purpose – Fibrous porous media have a wide variety of applications in insulation, filtration, acoustics, sensing, and actuation. To design such materials, computational modeling methods are needed to engineer the properties systematically. There is a lack of efficient approaches to build and modify those complex structures in computers. The paper aims to discuss these issues. Design/methodology/approach – In this paper, the authors generalize a previously developed periodic surface (PS) model so that the detailed shapes of fibers in porous media can be modeled. Because of its periodic and implicit nature, the generalized PS model is able to efficiently construct the three-dimensional representative volume element (RVE) of randomly distributed fibers. A physics-based empirical force field method is also developed to model the fiber bending and deformation. Findings – Integrated with computational fluid dynamics (CFD) analysis tools, the proposed approach enables simulation-based design of fibrous porous media. Research limitations/implications – In the future, the authors will investigate robust approaches to export meshes of PS models directly to CFD simulation tools and develop geometric modeling methods for composite materials that include both fibers and resin. Originality/value – The proposed geometric modeling method with implicit surfaces to represent fibers is unique in its capability of modeling bent and deformed fibers in a RVE and supporting design parameter-based modification for global configuration change for the purpose of macroscopic transport property analysis.

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