Three-Dimensional Numerical Calculations of Flow and Plume Spreading Past Cooling Towers

1987 ◽  
Vol 109 (1) ◽  
pp. 113-119 ◽  
Author(s):  
A. O. Demuren ◽  
W. Rodi
Keyword(s):  
Temperature Field ◽  
Computer Model ◽  
Cooling Tower ◽  
Three Dimensional ◽  
Computer Code ◽  
Quantitative Agreement ◽  
Cooling Towers ◽  
Rectangular Grid ◽  
Complex Flow ◽  
Densimetric Froude Number

The paper reports on the application of an existing three-dimensional computer code to the calculation of the flow and temperature field past cooling towers. The code uses a rectangular grid so that the round tower geometry has be approximated by steps. Simulations are presented of various idealized laboratory studies carried out with cylindrical cooling tower models with the ratio of plume exit to cross-wind velocity varying in the range 0.2 to 1.7 and the densimetric Froude number in the range ∞ to 2. By comparison with the experimental results it is shown that the computer model is capable of reproducing the main features of the complex flow and temperature field past cooling towers including the downwash effect at strong cross winds. The quantitative agreement is not always entirely satisfactory, and suggestions are made for improving the computer model.

Computational Models for Predicting Cooling Tower Fill Performance in Cross-Counterflow Configuration

2010 ◽  
Author(s):  
Hanno C. R. Reuter ◽  
Detlev G. Kro¨ger
Keyword(s):  
Computational Models ◽  
Cooling Tower ◽  
Air Flow ◽  
Three Dimensional ◽  
Cooling Water ◽  
Transfer Characteristic ◽  
Linear Interpolation ◽  
Water Evaporation ◽  
Cooling Towers ◽  
Flow Angle

In cooling towers packed with trickle or splash fills, which have almost isotropic or anisotropic flow resistance, the air flow through the fill is oblique or in cross-counterflow to the water flow, particularly at the cooling tower inlet when the fill loss coefficient is small or when the fill hangs down into the air inlet region. This results that the fill Merkel number or transfer characteristic for cross-counter flow is between that of purely counter- and crossflow fills. When using CFD to model natural draught wet-cooling tower performance for isotropic fill resistance, two- or three-dimensional models are therefore required to determine fill performance. In this paper, the governing fundamental partial differential equations are derived in cylindrical and Cartesian co-ordinates to determine the cooling water temperature, water evaporation rate, air temperature and air humidity ratio in two-dimensional cross-counterflow fills for both saturated and supersaturated air. To solve these equations, a relation is proposed to determine Merkel numbers for oblique air flows by linear interpolation and extrapolation of purely cross- and counterflow Merkel numbers in terms of the air flow angle. This model is compared to analytical Merkel numbers obtained for different air flow angles using a single drop trajectory model. A linear upwind computational model and an Eulerian FLUENT® model are developed to evaluate fill performance characteristics from test data and to model fill performance in cooling towers respectively. The results of these two models are compared and verified with a FLUENT® Euler-Lagrange model.

Experimental and Numerical Analysis of Compressor Inlet Volutes

1997 ◽  
Author(s):  
V. Michelassi ◽  
M. Giachi
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Computer Code ◽  
Navier Stokes ◽  
Complex Flow ◽  
Flow Distortion ◽  
Navier Stokes Equations ◽  
Flow Angle ◽  
Compressor Impeller ◽  
Compressor Inlet

A typical compressor inlet volute is studied by using both experimental and numerical approaches. The highly distorted and complex flow pattern is measured in two typical configurations. Measurements include velocity, flow angle, Mach number and losses. The same geometries are analyzed by using a computer code which solves the three-dimensional Navier-Stokes equations. Turbulence effects are modeled by a two-equation turbulence model. The set of measurements shows the flow distortion induced by the volute, and also highlights how this distortion can be controlled or largely reduced by small modifications to the geometry. The computational results indicate an overall good agreement with the measurements and allow reproducing the changes in the pattern induced by the changes in volute geometry. Both the measurements and computations prove the importance of the optimal design of this component which controls the uniformity of the flow approaching the compressor impeller.

Three-Dimensional Flowfield Prediction

1994 ◽  
Author(s):  
T.-K. Lin ◽  
D. G. Lilley
Keyword(s):  
Three Dimensional ◽  
Computer Code ◽  
Rectangular Grid ◽  
Explicit Formulation ◽  
Jet Mixing ◽  
Mass Fractions ◽  
Time Marching ◽  
Graphic Displays ◽  
Difference Time ◽  
Uniform Rectangular Grid

Abstract The development, use and application of a three-dimensional fluid flow computer code is described. The code runs on microcomputers with effective 3-D perspective color graphic displays of the results. The present version of the code retains several simplifications, uses a uniform rectangular grid system, and runs on microcomputers, thus providing a powerful and economical software capability. Equations are solved for the fully 3-D problem, including pressure, three velocity components and species mass fractions. The simulation is a finite difference time-marching procedure using an explicit formulation of the conservation equations, followed at each step by an iteration updating pressures and velocities so as to impose the continuity requirement. The present paper documents the problem, describes briefly its simulation, theory and assumptions, and gives results showing an application of the code to co-flowing round jet mixing.

Exploration of a Potential-Flow-Based Compact Model of Air-Flow Transport in Data Centers

2009 ◽  
Author(s):  
Michael M. Toulouse ◽  
Guislain Doljac ◽  
Van P. Carey ◽  
Cullen Bash
Keyword(s):  
Temperature Field ◽  
Data Center ◽  
Potential Flow ◽  
Air Flow ◽  
Three Dimensional ◽  
Convective Transport ◽  
Compact Model ◽  
Cfd Modeling ◽  
Complex Flow ◽  
Three Dimensional Flow

This paper summarizes an exploration of a compact model of air flow and transport in data centers developed from potential flow theory. Boundaries for the airflow in the data center are often complex due to the numerous rows of servers and other equipment in the facility, and there are generally multiple air inlets and outlets, which produce a fairly complex three-dimensional flow field in the air space in the data center. The general problem of airflow and convective transport in a data center requires accurate treatment of a turbulent flow in a complex flow passage with some buoyancy effects. As a result, full CFD thermofluidic models tend to be time-consuming and tedious to set up for such complex flow circumstances. In this initial study, we formulated an approximate model that retains only the most basic physical mechanisms of the flow. The resulting model of air flow in the data center is based on potential flow theory, which is exact for irrotational inviscid flow. The temperature field resulting from server heat input is determined by solving the convective energy transport equation along potential flow streamlines. This innovative approach, which takes advantage of the irrotational character of the modeled flow, provides a fast computational method for determining the temperature field and convective transport of thermal energy in the data center. Computations to predict the three-dimensional flow and temperature fields with the model typically require less than 60 seconds to complete on a laptop computer. Flow and temperature field results predicted by the model for typical data center flow circumstances are presented and limitations of the model are assessed. Features of an intuitive graphical user interface for the model that simplifies input of the data center design parameters are also described. Results for case studies indicate low sensitivity to mesh size and convergence criteria. Although the flow and temperature field models developed here are more approximate than full CFD methods, they are good first approximations that provide the means to rapidly explore the parameter space for the data center design. This model can be used to quickly identify the optimal region of the design space, whereupon a more detailed CFD modeling can be used to fine-tune an optimal design. The results of this investigation demonstrate that this type of fast compact model can be a very useful tool when used as a precursor to full CFD modeling in data center design optimization.

Computational Models for Predicting Cooling Tower Fill Performance in Cross-Counterflow Configuration

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
H. C. R. Reuter ◽  
D. G. Kröger
Keyword(s):  
Computational Models ◽  
Cooling Tower ◽  
Air Flow ◽  
Three Dimensional ◽  
Cooling Water ◽  
Transfer Characteristic ◽  
Linear Interpolation ◽  
Water Evaporation ◽  
Cooling Towers ◽  
Flow Angle

In cooling towers packed with trickle or splash fills, which have anisotropic flow resistance, the air flow through the fill is oblique or in cross-counterflow to the water flow, particularly at the cooling tower inlet when the fill loss coefficient is small or when the fill hangs down into the air inlet region. This results in that the fill Merkel number or transfer characteristic for cross-counter flow is between that of purely counter- and crossflow fills. When using CFD to model natural draught wet-cooling tower performance for isotropic fill resistance, two- or three-dimensional models are therefore required to determine fill performance. In this paper, the governing fundamental partial differential equations are derived in cylindrical and Cartesian coordinates to determine the cooling water temperature, water evaporation rate, air temperature, and air humidity ratio in two-dimensional cross-counterflow fills for both saturated and supersaturated air. To solve these equations, a relation is proposed to determine Merkel numbers for oblique air flows by linear interpolation and extrapolation of purely cross- and counterflow Merkel numbers in terms of the air flow angle. This model is compared to analytical Merkel numbers obtained for different air flow angles using a single drop trajectory model. A linear upwind computational model and an Eulerian FLUENT® model are developed to evaluate fill performance characteristics from test data and to model fill performance in cooling towers, respectively. The results of these two models are compared and verified with a FLUENT Euler–Lagrange model, showing minor deviations.

Using Viscous Calculations in Pump Design

1990 ◽  
Vol 112 (3) ◽  
pp. 272-280 ◽  
Author(s):  
F. Martelli ◽  
V. Michelassi
Keyword(s):  
High Performance ◽  
Incompressible Flows ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Computer Code ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Viscous Effects ◽  
Complex Flow ◽  
Pump Design

A viscous computer code for designing the meridional channels of high-performance pumps is presented. An averaging technique is used to reduce the three-dimensional flow to a two-dimensional model. The code, based upon an implicit finite difference method for steady two-dimensional incompressible flows, was validated in complex flow geometries prior to application in the design analysis of an actual pump. Viscous effects are taken into account by two different turbulence models. The Navier-Stokes solver is used in conjunction with a standard blade-to-blade calculation by means of an automatic graphic procedure that exchanges geometric and flowfield data. Various meridional shape solutions are presented and discussed in relation to physical evidence.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

scholarly journals Lath Martensite Microstructure Modeling: A High-Resolution Crystal Plasticity Simulation Study

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 691
Author(s):  
Francisco-José Gallardo-Basile ◽  
Yannick Naunheim ◽  
Franz Roters ◽  
Martin Diehl
Keyword(s):  
High Resolution ◽  
Mechanical Behavior ◽  
Crystal Plasticity ◽  
Lath Martensite ◽  
Three Dimensional ◽  
Building Blocks ◽  
Quantitative Agreement ◽  
Carbon Steels ◽  
Plastic Behavior ◽  
Austenitic Phase

Lath martensite is a complex hierarchical compound structure that forms during rapid cooling of carbon steels from the austenitic phase. At the smallest, i.e., ‘single crystal’ scale, individual, elongated domains, form the elemental microstructural building blocks: the name-giving laths. Several laths of nearly identical crystallographic orientation are grouped together to blocks, in which–depending on the exact material characteristics–clearly distinguishable subblocks might be observed. Several blocks with the same habit plane together form a packet of which typically three to four together finally make up the former parent austenitic grain. Here, a fully parametrized approach is presented which converts an austenitic polycrystal representation into martensitic microstructures incorporating all these details. Two-dimensional (2D) and three-dimensional (3D) Representative Volume Elements (RVEs) are generated based on prior austenite microstructure reconstructed from a 2D experimental martensitic microstructure. The RVEs are used for high-resolution crystal plasticity simulations with a fast spectral method-based solver and a phenomenological constitutive description. The comparison of the results obtained from the 2D experimental microstructure and the 2D RVEs reveals a high quantitative agreement. The stress and strain distributions and their characteristics change significantly if 3D microstructures are used. Further simulations are conducted to systematically investigate the influence of microstructural parameters, such as lath aspect ratio, lath volume, subblock thickness, orientation scatter, and prior austenitic grain shape on the global and local mechanical behavior. These microstructural features happen to change the local mechanical behavior, whereas the average stress–strain response is not significantly altered. Correlations between the microstructure and the plastic behavior are established.

scholarly journals Cooling tower plume abatement and plume modeling: a review

2021 ◽  
Author(s):  
Shuo Li ◽  
M. R. Flynn
Keyword(s):  
Public Health ◽  
Solar Energy ◽  
Cooling Tower ◽  
Plume Rise ◽  
Cooling Towers ◽  
Moist Air ◽  
Novel Technologies ◽  
Plume Modeling ◽  
Dry Cooling Tower ◽  
Dry Cooling

AbstractVisible plumes above wet cooling towers are of great concern due to the associated aesthetic and environmental impacts. The parallel path wet/dry cooling tower is one of the most commonly used approaches for plume abatement, however, the associated capital cost is usually high due to the addition of the dry coils. Recently, passive technologies, which make use of free solar energy or the latent heat of the hot, moist air rising through the cooling tower fill, have been proposed to minimize or abate the visible plume and/or conserve water. In this review, we contrast established versus novel technologies and give a perspective on the relative merits and demerits of each. Of course, no assessment of the severity of a visible plume can be made without first understanding its atmospheric trajectory. To this end, numerous attempts, being either theoretical or numerical or experimental, have been proposed to predict plume behavior in atmospheres that are either uniform versus density-stratified or still versus windy (whether highly-turbulent or not). Problems of particular interests are plume rise/deflection, condensation and drift deposition, the latter consideration being a concern of public health due to the possible transport and spread of Legionella bacteria.

Sign in / Sign up

Export Citation Format

Share Document