The CFD modeling of bund overtopping phenomena and prediction of dynamic pressure on the bund

In this paper, a study of gasdynamic processes that occur in a low-flow aerothermopressor has been done. The aerothermopressor is a two-phase jet apparatus for contact cooling, in which, due to the removal of heat from the air flow, the air pressure is increased (thermogasdynamic compression) and its cooling is taken place. Highly effective operation of the aerothermopressor is influenced by primarily the flow part design and the water injected method in the apparatus. Constructive factors that influence energy costs to overcome friction losses and local resistances on the convergent-divergent sections of the aerothermopressor are exerted a significant impact on the working processes in the apparatus. In this paper, a study of a number of typical low-flow aerothermopressor models has been conducted by using computer CFD modeling. Determination of the main parameters of the air flow (total pressure, dynamic pressure, velocity, temperature, etc.) has been carried out for a number of taper angles of a confuser a and a diffuser b, as well as for a number of values of the relative air velocity in the working chamber M = 0.4-0.8. Comparison of the obtained data with experimental data has been carried out. The deviation of the calculated values of local resistances coefficients in the confuser and in the diffuser from those obtained by computer CFD modeling does not exceed 7–10%. The recommended angles were determined: confuser convergent angle – 30° and diffuser divergent angle – 6°, corresponding to the minimum pressure loss is 1.0 – 9.5 %, and therefore also to the maximum pressure increase as a result of the thermogasdynamic compression that occurs during injection and evaporation of liquid in the working chamber. Thus, analytical dependences are obtained for determining the local resistance coefficients for the confuser (nozzle) and the diffuser, which can be recommended to use in the design methodology for low-flow aerothermopressors.

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Fixed Vane Stator Development for Axial Fan Performance Improvement in Electronics Cooling

ASME 2007 InterPACK Conference, Volume 2 ◽

10.1115/ipack2007-33306 ◽

2007 ◽

Author(s):

Gavin D. Stanley

Keyword(s):

Design Of Experiments ◽

Acoustic Noise ◽

Dynamic Pressure ◽

Electronics Cooling ◽

Leading Edge ◽

Cfd Modeling ◽

Axial Fan ◽

Development Method ◽

Stator Vane ◽

Axial Fans

An analysis and development method for augmenting flow and pressure performance of electronic cooling axial fans using a fixed vane stator is established using classical hand calculations, 2-dimensional (2D) Computational Fluid Dynamics (CFD) analysis, data from a design of experiments, and 3-dimensional (3D) CFD modeling. Where the size of electronic enclosures may disallow an increase in diameter of axial fans but allow for an increase in depth; a fixed vane stator is implemented to recapture lost dynamic pressure associated with swirl and radial flow vectors from the axial fan blades thus augmenting the pressure/flow curve of the unit. Stator blade effectiveness is evaluated and optimized first using data associated with National Advisory Committee for Aeronautics (NACA) airfoil shapes and then using 2-dimensional (2D) CFD analyses on both the impeller and stator blades. CFD modeling approaches and solving methods are discussed. A Design of Experiments (DOE) is utilized to verify and optimize the performance of the stator vanes and identifies the effectiveness of the stator vane angle, curvature of the stator leading edge, and number of stator vanes. At a constant back pressure the best performing DOE geometry delivered a 22% improvement in flow at constant electrical power input and a 41% improvement in flow at constant acoustic noise. This result was confirmed using a 3D CFD modeling. This analysis and development method provides a good baseline for evaluating and choosing proper stator vane geometries for flow improvement in axial fans.

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Function of arteries and veins in conditions of simulated cardiac arrest

Bioimpacts ◽

10.34172/bi.2021.13 ◽

2021 ◽

Vol 11 (2) ◽

pp. 157-164

Author(s):

Seyed Mehdi Kamali Shahri ◽

Christian Contarino ◽

Francesco Chifari ◽

Morteza Mahmoudi ◽

Simon Gelman

Keyword(s):

Blood Flow ◽

Cardiac Arrest ◽

Dynamic Pressure ◽

Venous Blood ◽

Elastic Fiber ◽

Venous System ◽

Cfd Modeling ◽

Venous Blood Flow ◽

Blood Flow Dynamics ◽

Different Diameters

Introduction: The study examined the behavior of vasculature in conditions of eliminated cardiac function using mathematical modeling. In addition, we addressed the question of whether the stretch-recoil capability of veins, at least in part accounts for the slower response to simulated cardiac arrest. Methods: In the first set of computational experiments, blood flow and pressure patterns in veins and arteries during the first few seconds after cardiac arrest were assessed via a validated multi-scale mathematical model of the whole cardiovascular system, comprising cardiac dynamics, arterial and venous blood flow dynamics, and microcirculation. In the second set of experiments, the effects of stretch-recoil zones of venous vessels with different diameters and velocities on blood velocity and dynamic pressure analyzed using computational fluid dynamics (CFD) modeling. Results: In the first set of experiments, measurement of changes in velocity, dynamic pressure, and fluid flow revealed that the venous system responded to cardiac arrest more slowly compared to the arteries. This disparity might be due to the intrinsic characteristics of the venous system, including stretch-recoil and elastic fiber composition. In the second set of experiments, we attempted to determine the role of the stretch-recoil capability of veins in the slower response to cardiac arrest. During the second set of experiments, we found that this recoil behavior increased dynamic pressure, velocity, and blood flow. The enhancement in dynamic pressure through combining the results from both experiments yielded a 15-40% increase in maximum dynamic pressure due to stretch-recoil, depending on vein diameter under normal conditions. Conclusion: In the situation of cardiac arrest, the vein geometry changes continue, promoting smooth responses of the venous system. Moreover, the importance of such vein behavior in blood displacement may grow as the pressure on the venous side gradually decreases with time. Our experiments suggest that the driving force for venous return is the pressure difference that remains within the venous system after the energy coming from every ventricular systole spent to overcome the resistance created by arterial and capillary systems.

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Modeling and Mitigation of Acoustic Induced Vibration (AIV) in Piping Systems

Volume 7: Operations, Applications, and Components ◽

10.1115/pvp2018-84107 ◽

2018 ◽

Author(s):

Brandon L. Ridens ◽

Timothy C. Allison ◽

Sarah B. Simons ◽

Klaus Brun

Keyword(s):

Dynamic Pressure ◽

Pressure Fluctuations ◽

Mitigation Strategies ◽

Cfd Modeling ◽

Screening Methods ◽

Element Analysis ◽

Modeling And Analysis ◽

Pressure Transducers ◽

Piping Systems ◽

The Impact

This paper explores new analysis techniques and mitigation concepts developed to extend the current state of the art acoustic induced vibrations (AIV) analyses. These new methods are intended to provide more accurate evaluations of this phenomenon in an attempt to solve AIV problems found in blowdown and piping systems. Current screening methods for AIV are based on pass/fail data with minimal or undesired options for reducing the likelihood of failure for AIV events. Computational fluid dynamics simulations and finite element analysis in combination with lab testing of novel mitigation options using accelerometers, dynamic pressure transducers, and strain gages were performed to better understand the phenomenon and develop possible solutions to reduce the impact of AIV on piping systems. Results of the testing and analyses performed at the Southwest Research Institute (SwRI) indicate that there is a possible correlation with acoustic modes, structural modes, and elevated stresses during AIV events. Minor reductions in dynamic pressure fluctuations throughout piping during AIV events can be made by changes in valve geometry and piping configurations. Results of CFD modeling and analysis demonstrate that computational analysis can be used to evaluate mitigation strategies and suggest that the use of a dampener as a mitigation technique may be successful in reducing the amplitudes of dynamic pressure waves in piping systems caused by AIV events.

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The Effects of Direction and Velocity of Movement, and Intra-Articular Fluid Volume on Intra-Articular Pressue

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0038-1633176 ◽

1988 ◽

Vol 01 (03/04) ◽

pp. 113-121 ◽

Cited By ~ 2

Author(s):

S. F. Straface ◽

P. J. Newbold ◽

S. Nade

Keyword(s):

Dynamic Pressure ◽

Volume Of Fluid ◽

Joint Capsule ◽

Fluid Volume ◽

Structural Configuration

levels. In joints with simulated acute effusion the effect of position on IAP was dependent upon the volume of fluid in the joint. The results indicate that dynamic pressure levels in the moving knee are related to the movements of the joint. The characteristic and reproducible patterns of pressure may reflect changes in the structural configuration of the joint capsule and surrounding tissues during movement, and are influenced by the amount of fluid in the joint.

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Recovery boiler sootblowers: History and technological advances

TAPPI Journal ◽

10.32964/tj14.1.51 ◽

2015 ◽

Vol 14 (1) ◽

pp. 51-60

Author(s):

HONGHI TRAN ◽

DANNY TANDRA

Keyword(s):

Cfd Modeling ◽

Computing Systems ◽

The Past ◽

Technological Advances ◽

Recovery Boilers ◽

Computational Fluid Dynamics Cfd ◽

Recovery Boiler ◽

Steam Parameters ◽

Insight Into ◽

Deposit Removal

Sootblowing technology used in recovery boilers originated from that used in coal-fired boilers. It started with manual cleaning with hand lancing and hand blowing, and evolved slowly into online sootblowing using retractable sootblowers. Since 1991, intensive research and development has focused on sootblowing jet fundamentals and deposit removal in recovery boilers. The results have provided much insight into sootblower jet hydrodynamics, how a sootblower jet interacts with tubes and deposits, and factors influencing its deposit removal efficiency, and have led to two important innovations: fully-expanded sootblower nozzles that are used in virtually all recovery boilers today, and the low pressure sootblowing technology that has been implemented in several new recovery boilers. The availability of powerful computing systems, superfast microprocessors and data acquisition systems, and versatile computational fluid dynamics (CFD) modeling capability in the past two decades has also contributed greatly to the advancement of sootblowing technology. High quality infrared inspection cameras have enabled mills to inspect the deposit buildup conditions in the boiler during operation, and helped identify problems with sootblower lance swinging and superheater platens and boiler bank tube vibrations. As the recovery boiler firing capacity and steam parameters have increased markedly in recent years, sootblowers have become larger and longer, and this can present a challenge in terms of both sootblower design and operation.

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CFD Modeling of Film Cooling Flow with Inclined Jets

Journal of Advances in Applied & Computational Mathematics ◽

10.15377/2409-5761.2016.03.01.5 ◽

2016 ◽

Vol 3 (1) ◽

pp. 29-33

Author(s):

Majid Almas ◽

Keyword(s):

Film Cooling ◽

Cfd Modeling ◽

Cooling Flow

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WET BURNING – THE MODERN TREND IN ENVIRONMENTAL BENIGN FUEL COMBUSTION AND IN SOLUTION TO THE PROBLEM OF SUSTAINABLE DEVELOPMENT OF THE POWER GENERATION

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2018.25-30.096-117 ◽

2018 ◽

pp. 96-117 ◽

Cited By ~ 2

Author(s):

B. S. Soroka

Keyword(s):

Numerical Simulation ◽

Nitrogen Oxides ◽

Chemical Kinetics ◽

Fuel Combustion ◽

Transport Processes ◽

Cfd Modeling ◽

Furnace Chamber ◽

Modern Trend ◽

Atmospheric Air ◽

No Formation

The article considers the role and place of water and water vapor in combustion processes with the purpose of reduction the effluents of nitrogen oxides and carbon oxide. We have carried out the complex of theoretical and computational researches on reduction of harmful nitrogen and carbon oxides by gas fuel combustion in dependence on humidity of atmospheric air by two approaches: CFD modeling with attraction of DRM 19 chemical kinetics mechanism of combustion for 19 components along with Bowman’s mechanism used as “postprocessor” to determine the [NO] concentration; different thermodynamic models of predicting the nitrogen oxides NO formation. The numerical simulation of the transport processes for momentum, mass and heat being solved simultaneously in the united equations’ system with the chemical kinetics equations in frame of GRI methane combustion mechanism and NO formation calculated afterwards as “postprocessor” allow calculating the absolute actual [CO] and [NO] concentrations in dependence on combustion operative conditions and on design of furnace facilities. Prediction in frame of thermodynamic equilibrium state for combustion products ensures only evaluation of the relative value of [NO] concentration by wet combustion the gas with humid air regarding that in case of dry air – oxidant. We have developed the methodology and have revealed the results of numerical simulation of impact of the relative humidity of atmospheric air on harmful gases formation. Range of relative air humidity under calculations of atmospheric air under impact on [NO] and [CO] concentrations at the furnace chamber exit makes φ = 0 – 100%. The results of CFD modeling have been verified both by author’s experimental data and due comparing with the trends stated in world literature. We have carried out the complex of the experimental investigations regarding atmospheric air humidification impact on flame structure and environmental characteristics at natural gas combustion with premixed flame formation in open air. The article also proposes the methodology for evaluation of the nitrogen oxides formation in dependence on moisture content of burning mixture. The results of measurements have been used for verification the calculation data. Coincidence of relative change the NO (NOx) yield due humidification the combustion air revealed by means of CFD prediction has confirmed the qualitative and the quantitative correspondence of physical and chemical kinetics mechanisms and the CFD modeling procedures with the processes to be studied. A sharp, more than an order of reduction in NO emissions and simultaneously approximately a two-fold decrease in the CO concentration during combustion of the methane-air mixture under conditions of humidification of the combustion air to a saturation state at a temperature of 325 K.

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