Prediction of LPCVD silicon film microstructure from local operating conditions using numerical modeling

1999 ◽  
Vol 09 (PR8) ◽  
pp. Pr8-181-Pr8-188 ◽  
Author(s):  
A. Dollet ◽  
B. Caussat ◽  
J. P. Couderc
Keyword(s):  
Numerical Modeling ◽  
Silicon Film ◽  
Operating Conditions ◽  
Film Microstructure

Numerical Modeling of the Critical Operating Conditions for a Hydraulic Lubrication System in a Heavy-Duty Tractor Driveline

2021 ◽  
Author(s):  
Andrea Polito ◽  
Luca Montorsi ◽  
Gabriele Muzzioli ◽  
Gabriele Storchi ◽  
Massimo Milani
Keyword(s):  
Numerical Modeling ◽  
Operating Conditions ◽  
Lubrication System ◽  
Heavy Duty

The Effect of Geometrical Features on Air-Side Heat Transfer and Friction Characteristics, and Optimization of a Large-Size Plain Fin-and-Tube Heat Exchanger by 3-D Numerical Simulation

2009 ◽  
Author(s):  
M. Izadi ◽  
D. K. Aidun ◽  
P. Marzocca ◽  
H. Lee
Keyword(s):  
Heat Transfer ◽  
Numerical Modeling ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Simple Algorithm ◽  
Operating Conditions ◽  
Friction Characteristics ◽  
Tube Heat Exchanger ◽  
Large Size ◽  
Geometrical Features

The effect of geometrical features on the air-side heat transfer and friction characteristics of an industrial plain fin-and-tube heat exchanger is investigated by 3-D numerical modeling and simulations. The heat exchanger has been designed and employed as an intercooler in a gas power plant and is a large-size compact heat exchanger. Most of the available design correlations developed so far for plain fin–and–tube heat exchangers have been prepared for small-size exchangers and none of them fits completely to the current heat exchanger regarding the geometrical limitations of correlations. It is shown that neglecting these limitations and applying improper correlations may generate considerable amount of error in the design of such a large-size heat exchanger. The geometry required for numerical modeling is produced by Gambit® software and the boundary conditions are defined regarding the real operating conditions. Then, three-dimensional simulations based on the SIMPLE algorithm in laminar flow regime are performed by FLUENT™ code. The effect of fin pitch, tube pitch, and tube diameter on the thermo-hydraulic behavior of the heat exchanger is studied. Some variations in the design of the heat exchanger are suggested for optimization purposes. It is finally concluded that the current numerical model is a powerful tool to design and optimize of large-size plain fin-and-tube heat exchangers with acceptable accuracy.

Experimental Validation of Computer Models for Food and Polymer Extrusion

2003 ◽  
Author(s):  
Yogesh Jaluria
Keyword(s):  
Numerical Modeling ◽  
Numerical Models ◽  
Strong Support ◽  
Chemical Conversion ◽  
Operating Conditions ◽  
Experimental Results ◽  
Twin Screw Extruders ◽  
Twin Screw ◽  
Temperature Dependent Properties ◽  
Good Agreement

The accuracy and validity of the mathematical and numerical modeling of extruders for polymers and for food are considered in terms of experimental results obtained on typical full-size single and twin-screw extruders. The fluid is treated as non-Newtonian and with strong temperature-dependent properties. The chemical conversion of food during extrusion is also considered. The numerical modeling is employed for steady-state transport, for a range of operating conditions. Following grid-independence studies, the results obtained are first considered in terms of the expected physical behavior of the process, yielding good agreement with observations presented in the literature. The results are then compared with detailed and qualitative experimental results available from previous investigations to evaluate their accuracy. Good agreement with experimental data is obtained, lending strong support to the mathematical and numerical models.

Main Results of Na-K Alloy Boiling Investigation

2002 ◽  
Author(s):  
G. A. Sorokin ◽  
G. P. Bogoslovskaya ◽  
E. F. Ivanov ◽  
A. P. Sorokin
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Modeling ◽  
Liquid Metal ◽  
Critical Heat Flux ◽  
Liquid Metals ◽  
Operating Conditions ◽  
Coolant Temperature ◽  
Low Velocity ◽  
Experimental Conditions

Boiling experiments on eutectic sodium-potassium alloy in the model of fast reactor subassembly under conditions of low-velocity circulation carried out at the IPPE call for further investigations into numerical modeling of the process. The paper presents analysis of pin bundle liquid metal boiling, stages of the process, its characteristics (wall temperature, coolant temperature, flow rate. pressure void fraction and others), that allowed the pattern map to be drawn. The problem of conversion of the data gained in Na-K mock-up experiments to in-pile sodium reactor operating conditions is analyzed here, as well as thermodynamic similarity of liquid metal coolants and eutectic Na-K alloy. Data on bundle boiling in Na-K are presented in comparison with those in different liquid metals. Analysis of data on liquid metal heat transfer in cases of pool boiling, boiling in tubes, in slots, and in pin bundles, as well as data on critical heat flux in tubes was performed and discussed in the paper. The relationship for calculation of critical heat flux in liquid metal derived by the authors is presented. Results of numerical modeling of liquid metal boiling heat transfer during accident cooling of reactor core applied to experimental conditions of going from forced to natural circulation are presented, too.

Numerical Modeling of Turbulent Cavitation Flows in Safety Relief Valves

2014 ◽  
Author(s):  
Anthony Couzinet ◽  
Laurent Gros ◽  
Jorge Pinho ◽  
Said Chabane ◽  
Daniel Pierrat
Keyword(s):  
Numerical Modeling ◽  
Flow Visualization ◽  
Discharge Coefficient ◽  
Incompressible Flows ◽  
Control Valve ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Relief Valve ◽  
Ansys Cfx ◽  
Experimental Approaches

Safety relief valve (SRV) is still the ultimate security component of pressure vessels or piping equipment. It does not take the place of a regulating or control valve but it aims to protect devices and people by preventing damage due to overpressure in the system. This is ensured by discharging an amount of fluid when excessive rising pressure occurs. For the incompressible flows, the discharge coefficient of the relief valve can be modified by cavitation development under specific operating conditions. Then, the sizing of the valve doesn’t correspond to the flow discharged resulting in severe damage. This study aims to demonstrate the capability of numerical modeling to predict the evolution of discharge coefficient under cavitation conditions. URANS simulations have been performed with ANSYS CFX 13.0 using Shear Stress Transport modeling. A Rayleigh-Plessey model is used to predict the development of cavitation in the relief valve. A modification of the saturation vapor pressure is proposed in the cavitation model to take into account the turbulent effects on the cavitation development. Additionally a Plexiglas mock-up has been built for flow visualization and two valve discs are used to measure the discharge coefficient or the flow force acting on the valve. Numerical and experimental approaches are compared first by analyzing qualitative results through flow visualization and also by evaluating hydraulic characteristics of the SRV.

scholarly journals Numerical Modeling of Wear in a Thrust Roller Bearing under Mixed Elastohydrodynamic Lubrication

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 58 ◽  
Author(s):  
Andreas Winkler ◽  
Max Marian ◽  
Stephan Tremmel ◽  
Sandro Wartzack
Keyword(s):  
Numerical Modeling ◽  
Wear Behavior ◽  
Roller Bearing ◽  
Numerical Procedure ◽  
Elastohydrodynamic Lubrication ◽  
Numerical Approach ◽  
Operating Conditions ◽  
Oil Viscosity ◽  
Low Viscosity ◽  
Machine Elements

Increasing efforts to reduce frictional losses and the associated use of low-viscosity lubricants lead to machine elements being operated under mixed lubrication. Consequently, wear effects are also gaining relevance. Appropriate numerical modeling and predicting wear in a reliable manner offers new possibilities for identifying harmful operating conditions or for designing running-in procedures. However, most previous investigations focused on simplified model contacts and the wear behavior of application-oriented contacts is relatively underexplored. Therefore, the contribution of this paper was to provide a numerical procedure for studying the wear evolution in the mixed elastohydrodynamically lubricated (EHL) roller/raceway contact by coupling a finite element method (FEM)-based 3D EHL model with surface topography changes following a local Archard-type wear model, a Greenwood–Williamson-based load-sharing approach and the Sugimura surface adaption model. This study applied the operating conditions of an 81212 thrust roller bearing, considering realistic geometry and locally varying velocities. The calculated wear profiles in the raceway featured asymmetries, which were in good agreement with the experimental results reported in the literature and could be correlated with the velocity and slip distribution. In addition, the effects of speed, load and oil viscosity were investigated by means of four load cases and two lubricants, demonstrating the broad range of applying the numerical approach.

The Influence of Cooling Flows on the Operating Conditions of the Ultra-Supercritical Steam Turbine Components

2010 ◽  
Author(s):  
Wojciech Kosman
Keyword(s):  
Numerical Modeling ◽  
Steam Turbine ◽  
Power Plants ◽  
Measurement Data ◽  
Test Stand ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Inlet Section ◽  
Steam Turbines ◽  
Cooling Flows

This paper presents the results of the analysis on the heat transfer in the inlet section of an ultra-supercritical steam turbine. Such power generating units become the foundation of new coal-fired power plants. The monitoring of their operation is in many aspects similar to the traditional, sub-critical steam turbines. However, higher live and reheat steam parameters result in several key differences, which must be taken into the consideration when assessing the thermal and strength states of the turbines main components for the diagnostic supervision. One of the main differences is the presence of the cooling and designs specific for ultra-supercritical steam turbines, which aim to protect their components against overheating. The research described in this paper investigates the inlet section of the turbines, which is the area exposed to the highest thermal loads. The scope of the research includes both, numerical modeling and laboratory testing. A test stand has been built for the analysis of the flows in the inlet section. Cooling flows are under special attention here as their temperature field is coupled to the temperature fields of the turbine components (the rotor and the inner casing) due to the relatively small amount of the coolant. The paper provides detailed description of the test stand and some early measurement results, which involve the operation with cooling. Also the numerical modeling results are shown and compared to the measurement data.

Validation of Twin-Screw Polymer Extruder Modeling

2002 ◽  
Author(s):  
Yogesh Jaluria
Keyword(s):  
Numerical Modeling ◽  
Numerical Models ◽  
Polymeric Materials ◽  
Operating Conditions ◽  
Design Parameters ◽  
Design And Optimization ◽  
Single Screw Extruder ◽  
Twin Screw ◽  
Accuracy Of Results ◽  
Mathematical And Numerical Modeling

The mathematical and numerical modeling of twin-screw polymer extruders is examined with respect to accuracy of results and validity of the simulation. A numerical model is developed incorporating the translation region, which is similar to a single-screw extruder channel, and the intermeshing, or nip, region. The numerical modeling is carried out for steady and time-dependent operation, considering various polymeric materials like polyethylene and corn meal. A range of design parameters and operating conditions are considered. The results are evaluated in terms of the expected physical behavior of the system and compared with experimental results available in the literature to determine the accuracy of the predictions. In many cases, only qualitative comparisons are possible since the operating conditions and design parameters are not explicitly known. However, the basic trends are as expected and good quantitative comparisons with experimental data is used to validate the model. Validated numerical models can extend the domain of relevant inputs for process design and optimization.

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