Editorial

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3 pages, 167 KiB

Open AccessEditorial

Special Issue: Applied Computational Fluid Dynamics (CFD)

by Kristian Etienne Einarsrud, Varun Loomba and Jan Erik Olsen

Processes 2023, 11(2), 461; https://doi.org/10.3390/pr11020461 - 03 Feb 2023

Cited by 1 | Viewed by 1242

Abstract

Many industrial and manufacturing processes exhibit complex and coupled fluid flow phenomena [...] Full article

(This article belongs to the Special Issue Applied Computational Fluid Dynamics (CFD))

Research

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16 pages, 6488 KiB

Open AccessFeature PaperArticle

A Computational Fluid Dynamic Study of Developed Parallel Stations for Primary Fans

by Juan Pablo Hurtado, Gabriel Reyes, Juan Pablo Vargas and Enrique Acuña

Processes 2021, 9(9), 1607; https://doi.org/10.3390/pr9091607 - 08 Sep 2021

Cited by 2 | Viewed by 2060

Abstract

A Computational fluid dynamic (CFD) model was developed considering three geometries for primary parallel fan stations that have already been developed, implemented, and are currently in operation within Chilean mines. To standardize the comparison, the same primary fan was used in all the [...] Read more.

A Computational fluid dynamic (CFD) model was developed considering three geometries for primary parallel fan stations that have already been developed, implemented, and are currently in operation within Chilean mines. To standardize the comparison, the same primary fan was used in all the simulations with a unique set of settings (speed, blade angle, and density). The CFD representation was used to determine the operating point per configuration and compare the performances in terms of airflow and pressure delivered. This approach allowed ranking primary fan station geometry based on resistance curve and energy consumption of the fan. This paper presents the results obtained through the CFD simulations and the corresponding primary fans operating points of each configuration: symmetrical branches (SB), overlap branches (OB), and run around (RA) bypass. The RA configuration was identified as the best-performing station geometry on the lowest frictional and shock pressure losses, highest airflow delivery, and lowest energy cost. The results are discussed, considering pressure, velocity, and vector contours to understand the fluid dynamics phenomena occurring inside the station. The capital cost involved in the development of each primary parallel station was considered in the analysis in addition to the energy cost to determine the economic configuration over time. Full article

(This article belongs to the Special Issue Applied Computational Fluid Dynamics (CFD))

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16 pages, 7606 KiB

Open AccessArticle

Optimization Study of Guide Vanes for the Intake Fan-Duct Connection Using CFD

by Juan Pablo Hurtado, Bryan Villegas, Sebastián Pérez and Enrique Acuña

Processes 2021, 9(9), 1555; https://doi.org/10.3390/pr9091555 - 31 Aug 2021

Cited by 8 | Viewed by 5604

Abstract

The connection between an intake fan and a ventilation shaft must be designed in such a way that it minimizes the energy waste due to singularity losses. As a result, the questions of which radius of curvature to use and if guide vanes [...] Read more.

The connection between an intake fan and a ventilation shaft must be designed in such a way that it minimizes the energy waste due to singularity losses. As a result, the questions of which radius of curvature to use and if guide vanes have to be included need to be answered. In that case, the variables such as the number, upstream and downstream penetration length, radius of curvature, and width of the vanes, need to be defined. Although this work is oriented to mine ventilation, these questions are usually valid in other engineering applications as well. The objective of this study is to define the previously mentioned variables to determine the optimal design combination for the radius/diameter relationship (r/D). Computational fluid dynamics was used to determine the shock loss factor of seven elbow curvature ratios for a 3 m diameter duct and fan, with and without guide vanes to estimate the best performing configuration and, therefore, to maximize the fan airflow volume. The methodology used consisted of initially developing models in 2D geometries, to optimize the meshing and the CPU use, and studying separately the number of vanes, upstream and downstream penetration, radius of curvature, and width of the vanes for each curvature ratio (r/D). Then, the best-performing variable combinations for each curvature ratio were selected to be simulated and studied with the 3D geometries. The application of the guide vane designs for three-dimensional simulated geometries is presented, first without and then with guide vanes, including the shock loss factors obtained. The methodology and obtained results allowed quantifying the energy savings and to reduce the CFD simulations steps required to optimize the design of the elbow and guide vanes. The results obtained cannot be used with elbows in exhaust fans, because fluid dynamics phenomena are different. Full article

(This article belongs to the Special Issue Applied Computational Fluid Dynamics (CFD))

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15 pages, 4089 KiB

Open AccessFeature PaperArticle

How Do Operational and Design Parameters Effect Biomass Productivity in a Flat-Panel Photo-Bioreactor? A Computational Analysis

by Varun Loomba, Eric von Lieres and Gregor Huber

Processes 2021, 9(8), 1387; https://doi.org/10.3390/pr9081387 - 10 Aug 2021

Cited by 6 | Viewed by 1871

Abstract

Optimal production of microalgae in photo-bioreactors (PBRs) largely depends on the amount of light intensity received by individual algal cells, which is affected by several operational and design factors. A key question is: which process parameters have the highest potential for the optimization [...] Read more.

Optimal production of microalgae in photo-bioreactors (PBRs) largely depends on the amount of light intensity received by individual algal cells, which is affected by several operational and design factors. A key question is: which process parameters have the highest potential for the optimization of biomass productivity? This can be analyzed by simulating the complex interplay of PBR design, hydrodynamics, dynamic light exposure, and growth of algal cells. A workflow was established comprising the simulation of hydrodynamics in a flat-panel PBR using computational fluid dynamics, calculation of light irradiation inside the PBR, tracing the light exposure of individual cells over time, and calculation the algal growth and biomass productivity based on this light exposure. Different PBR designs leading to different flow profiles were compared, and operational parameters such as air inlet flowrate, microalgal concentration, and incident light intensity were varied to investigate their effect on PBR productivity. The design of internal structures and lighting had a significant effect on biomass productivity, whereas air inlet flowrate had a minimal effect. Microalgal concentration and incident light intensity controlled the amount of light intensity inside the PBR, thereby significantly affecting the overall productivity. For detailed quantitative insight into these dependencies, better parameterization of algal growth models is required. Full article

(This article belongs to the Special Issue Applied Computational Fluid Dynamics (CFD))

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20 pages, 1038 KiB

Open AccessArticle

A Eulerian Multi-Fluid Model for High-Speed Evaporating Sprays

by Robert Keser, Michele Battistoni, Hong G. Im and Hrvoje Jasak

Processes 2021, 9(6), 941; https://doi.org/10.3390/pr9060941 - 26 May 2021

Cited by 4 | Viewed by 1965

Abstract

Advancements in internal combustion technology, such as efficiency improvements and the usage of new complex fuels, are often coupled with developments of suitable numerical tools for predicting the complex dynamic behavior of sprays. Therefore, this work presents a Eulerian multi-fluid model specialized for [...] Read more.

Advancements in internal combustion technology, such as efficiency improvements and the usage of new complex fuels, are often coupled with developments of suitable numerical tools for predicting the complex dynamic behavior of sprays. Therefore, this work presents a Eulerian multi-fluid model specialized for the dynamic behavior of dense evaporating liquid fuel sprays. The introduced model was implemented within the open-source OpenFOAM library, which is constantly gaining popularity in both industrial and academic settings. Therefore, it represents an ideal framework for such development. The presented model employs the classes method and advanced interfacial momentum transfer models. The droplet breakup is considered using the enhanced WAVE breakup model, where the mass taken from the parent droplets is distributed among child classes using a triangular distribution. Furthermore, the complex thermal behavior within the moving droplets is considered using a parabolic temperature profile and an effective thermal conductivity approach. This work includes an uncertainty estimation analysis (for both spatial and temporal resolutions) for the developed solver. Furthermore, the solver was validated against two ECN Spray A conditions (evaporating and non-evaporating). Overall, the presented results show the capability of the implemented model to successfully predict the complex dynamic behavior of dense liquid sprays for the selected operating conditions. Full article

(This article belongs to the Special Issue Applied Computational Fluid Dynamics (CFD))

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16 pages, 5141 KiB

Open AccessArticle

Numerical Analysis of Heat Transfer and Pressure Drop in Helically Micro-Finned Tubes

by Muhammad Ammar Ali, Muhammad Sajid, Emad Uddin, Niaz Bahadur and Zaib Ali

Processes 2021, 9(5), 754; https://doi.org/10.3390/pr9050754 - 24 Apr 2021

Cited by 5 | Viewed by 2534

Abstract

In this study, the pressure drop and heat transfer characteristics of smooth tube and internal helically micro-finned tubes with two different fin-to-fin height ratios i.e., equal fin height and alternating fin height, are computationally analysed. The tube with alternating fin height is analysed [...] Read more.

In this study, the pressure drop and heat transfer characteristics of smooth tube and internal helically micro-finned tubes with two different fin-to-fin height ratios i.e., equal fin height and alternating fin height, are computationally analysed. The tube with alternating fin height is analysed for proof of concept of pressure drop reduction. A single phase steady turbulent flow model is used with a Reynolds number ranging from 12,000 to 54,000. Water is used as working fluid with inlet temperature of 55 °C and constant wall temperature of 20 °C is applied. Friction factor, heat transfer coefficient, Nusselt number, and Thermal Performance Index are evaluated and analysed. The numerical results are validated by comparison with the experimental and numerical data from literature. The results showed that the thermal performance is enhanced due to helically finned tube for a range of Reynolds numbers, but at the expense of increased pressure drop as compared to a smooth tube. The helically finned tube with alternating fin heights showed a 5% decrease in friction factor and <1% decrease in heat transfer coefficient when compared with the equal fin heights tube, making it a suitable choice for heat transfer applications. Full article

(This article belongs to the Special Issue Applied Computational Fluid Dynamics (CFD))

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18 pages, 2914 KiB

Open AccessArticle

Computational Study in Bottom Gas Injection Using the Conservative Level Set Method

by Jorge E. Rivera-Salinas, Karla M. Gregorio-Jáuregui, Alejandro Cruz-Ramírez, Víctor H. Gutierréz-Pérez, José A. Romero-Serrano, Seydy L. Olvera-Vazquez, Heidi A. Fonseca-Florido and Carlos A. Ávila-Orta

Processes 2020, 8(12), 1643; https://doi.org/10.3390/pr8121643 - 12 Dec 2020

Cited by 3 | Viewed by 2372

Abstract

This paper presents a computational study on bottom gas injection in a cylindrical tank. The bubble formation at submerged orifices, bubble rising, and interactions between bubbles and bubbles with the free surface were studied using the conservative level set method (CLSM). Since the [...] Read more.

This paper presents a computational study on bottom gas injection in a cylindrical tank. The bubble formation at submerged orifices, bubble rising, and interactions between bubbles and bubbles with the free surface were studied using the conservative level set method (CLSM). Since the gas injection is an important technique in various fields and this process is quite complicated, the scenario was chosen to quantify the efficacy of the CLSM to describe the gas-liquid complex interactions with fast changes in the surface tension force and buoyancy force. The simulation accuracy is verified with the grid convergence index (GCI) approach and Richardson Extrapolation (RE) and is validated by comparing the numerical results with experimental observations, theoretical equations, and published data. The results show that the CLSM accurately reproduces the bubble formation frequency, and that it can handle complicated bubble shapes. Moreover, it captures the challenging phenomena of interaction between bubbles and free surface, the jet of liquid produced when bubbles break through the free surface, and the rupture of the film of liquid. Therefore, the CLSM is a robust numerical technique to describe gas-liquid complex interactions, and it is suited to simulate the gas injection operation. Full article

(This article belongs to the Special Issue Applied Computational Fluid Dynamics (CFD))

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13 pages, 4736 KiB

Open AccessArticle

Design of Cyclone Separator Critical Diameter Model Based on Machine Learning and CFD

by Donggeun Park and Jeung Sang Go

Processes 2020, 8(11), 1521; https://doi.org/10.3390/pr8111521 - 23 Nov 2020

Cited by 16 | Viewed by 17343

Abstract

In this paper, the characteristics of the cyclone separator was analyzed from the Lagrangian perspective for designing the important dependent variables. The neural network network model was developed for predicting the separation performance parameter. Further, the predictive performances were compared between the traditional [...] Read more.

In this paper, the characteristics of the cyclone separator was analyzed from the Lagrangian perspective for designing the important dependent variables. The neural network network model was developed for predicting the separation performance parameter. Further, the predictive performances were compared between the traditional surrogate model and the developed neural network model. In order to design the important parameters of the cyclone separator based on the particle separation theory, the force acting until the particles are separated was calculated using the Lagrangian-based computational fluid dynamics (CFD) methodology. As a result, it was proved that the centrifugal force and drag acting on the critical diameter having a separation efficiency of 50% were similar, and the particle separation phenomenon in the cyclone occurred from the critical diameter, and it was set as an important dependent variable. For developing a critical diameter prediction model based on machine learning and multiple regression methods, unsteady-Reynolds averaged Navier-Stokes analyzes according to shape dimensions were performed. The input design variables for predicting the critical diameter were selected as four geometry parameters that affect the turbulent flow inside the cyclone. As a result of comparing the model prediction performances, the machine learning (ML) model, which takes into account the critical diameter and the nonlinear relationship of cyclone design variables, showed a 32.5% improvement in R-square compared to multi linear regression (MLR). The proposed techniques have proven to be fast and practical tools for cyclone design. Full article

(This article belongs to the Special Issue Applied Computational Fluid Dynamics (CFD))

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