A systematic approach to numerical analysis and validation for industrial oven design and optimization – A case study

Multi-objective Computational Fluid Dynamics (CFD) design optimisation in commercial bread-baking

Study on mud discharge after emergency disconnection of deepwater drilling risers

Solar chimneys are among the most common methods for natural ventilation of buildings. Computational Fluid Dynamics (CFD) has been widely applied in research and design of solar chimneys. Most of the previous studies are based on 2D CFD models which ignore the effects of the width (the third dimension) of the air channel. In addition, the applicability of 2D models for the solar chimneys with a low width-to-gap ratio is still questionable. This study investigates both 2D and 3D CFD models for window-sized vertical solar chimneys. The 2D model is applied to the domain comprising the central plane of the channel gap ( G) and height ( H) while the 3D model is applied to the domain consisting of the channel gap, height, and width ( W). The flow fields, flow rates and thermal efficiencies computed with the 2D and 3D models at different heights, gaps, and widths are compared. The results show that W/ G is the most crucial factor. The effects of the side walls are significant at a low W/ G but gradually diminishes as W/ G increases. At W/ G = 15, the side wall effects are confined to a region of about 2.6% W. Particularly, for W/ G>8, the differences between the 2D and 3D flow rates and thermal efficiencies are within ±5%. These findings offer a reference for researchers and engineers to select between 2D and 3D CFD models for a specific solar chimney.

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.

This article presents computational fluid dynamics (CFD) modeling of the flow processes at a certain specimen of an external gear pump. The purpose of the developed two-dimensional (2D) CFD model is to carry out a numerical study to obtain the main characteristics of the pump flow rate, especially the flow rate as a function of the pressure and the flow rate as a function of the time. A numerical study was carried out at forty-two different operating modes that were expressed as a variation of two parameters: rotational frequency (950–1450 min−1) and pressure (5–150 bar). The validation of the numerical results was carried out through an experimental study. For this purpose, a laboratory experimental setup equipped with a modern data acquisition (DAQ) system was designed and implemented. It allows the gear pump to be tested at the same operating modes as the numerical study. A validation analysis was performed by comparing the numerical and experimental results using the average relative error index (FIT). A detailed description of the 2D CFD model development (CAD model, mesh, general settings, boundary conditions, etc.) is provided. Based on the 2D CFD model, an original methodology was proposed to take into account the influence of the discharge channels on the displacement volume of the pump by adjusting the face width of the gears. Despite the limitations of the simple 2D CFD model, which are discussed in this article, a very good match between numerical and experimental results is analyzed by calculating the FIT level, which is in the range of 93–97%.

Design and optimization of trawl-doors are key factors in minimizing the fuel consumption of fishing vessels. This paper discusses optimization of the trawl-door shapes using high-fidelity 3D computational fluid dynamic (CFD) models. The accurate 3D CFD models are computationally expensive and, therefore, the direct use of traditional optimization algorithms, which often require a large number of evaluations, may be prohibitive. The design approach presented here is a variation of sequential approximate optimization exploiting low-order local response surface models of the expensive 3D CFD simulations. The algorithm is applied to the design of modern and airfoil-shaped trawl-doors.

Supercritical carbon dioxide (sCO2) power cycles could be a more efficient alternative to steam Rankine cycles for power generation from coal. In this paper, the end seal layout for a nominally 500 MWe sCO2 turbine is presented and the shaft end sealing requirements for such utility-scale sCO2 turbines are discussed. Shaft end leakage from a closed-loop sCO2 cycle and the associated recompression load can result in net cycle efficiency loss of about 0.55% points to 0.65% points for a nominally 500 MWe sCO2 power cycle plant. Low-leakage hydrodynamic face seals are capable of reducing this leakage loss (and net cycle efficiency loss), and are considered a key enabling component technology for achieving 50–52% or greater thermodynamic cycle efficiencies with indirect coal-fired sCO2 power cycles. In this paper, a hydrodynamic face seal concept is presented for end seals on utility-scale sCO2 turbines. A 3D computational fluid dynamics (CFD) model with real gas CO2 properties is developed for studying the physics of the thin fluid film separating the seal stationary ring and the rotor. The results of the 3D CFD model are also compared with the predictions of a Reynolds-equation-based solver. The 3D CFD model results show large viscous shear and the associated windage heating challenge in sCO2 face seals. Following the CFD model, an axisymmetric finite-element analysis (FEA) model is developed for parametric optimization of the face seal cross-section with the goal of minimizing the coning of the stationary ring. A preliminary thermal analysis of the seal is also presented. The fluid, structural and thermal results show that large-diameter (about 24 inch) face seals with small coning or out-of-plane deformations (of the order of 0.0005 inch) are possible. The fluid, structural and thermal results are used to highlight the design challenges in developing large-diameter and high-differential-pressure face seals for the operating conditions of utility-scale sCO2 turbines.

Closure to “Discussion: ‘Design Improvements to a Biomass Stirling Engine Using Mathematical Analysis and 3D CFD Modeling’ ” (2007, ASME J. Energy Resour. Technol., 129, pp. 278, 279, 280)

A practical application of a three-dimensional (3D) computational fluid dynamics (CFD) model to optimize the design of a storage reservoir for its use as a clearwell is presented in this paper. A computational grid of the 20 million gallon (MG) reservoir, incorporating 285 columns supporting the roof, was created from existing design drawings. Initial model simulations indicated poor mixing and contact time, with T10/T ratio of about 0.2, where T10 is the tenth percentile of the hydraulic residence time, T. Therefore, various baffle arrangements were investigated to increase the T10/T ratio to 0.72 and minimize the cost associated with retrofitting the reservoir with baffles. These duel considerations resulted in an unconventional design of the clearwell with an estimated cost saving of 45 percent. The paper analyzes the computed circulation patterns to identify the causes of significantly different hydraulic and mass transport characteristics of the reservoir, with and without columns, and the proposed design incorporating baffles.

Deep learning assisted anode porous transport layer inverse design for proton exchange membrane water electrolysis

At present, the oven has become a popular electrical product for home life，and its appearance design is based on a minimalist style, pursuing the purity of appearance and streamlining of functions. However, different users have different perceptions of the simplicity and ease of use of the oven design, which may lead to differences in aesthetic preferences and design requirements, which in turn may lead to varying degrees of use obstacles and poor experience. How to grasp the "degree" of Minimalist Design to meet the differentiated needs of more users? It is the main problem of oven design at this stage. However, the method researches of related Minimalist Design are mostly theoretical reference and lack practical guiding significance. Therefore, this article will focus on the concept of Minimalist Design, combined with multi-level demand theory and Analytic Hierarchy Process, to explore the differences in users’ aesthetic preferences for minimalist oven design, construct a multi-level structural model of user needs, obtain the importance of user needs, and summarize differentiated minimalist oven designs methods. First, hot-selling ovens were selected as the research objects; compared the relative simplicity difference of each two products , a difference matrix was obtained; Multi-Dimensional Scaling Analysis, Cluster Analysis, and K-means Clustering were applied, the simplicity of ovens was classified and each category Typical products were obtained as simple prototypes; questionnaire surveys and statistical tests were used, the characteristics of the user groups of each prototype were obtained; based on the concept of Minimalist Design, user interviews and other methods were applied, the simplicity of users on three levels of stable performance, smooth interaction, and minimalist appearance Design demand factors were obtained; finally, the Analytic Hierarchy Process was applied, a hierarchical model of simple design factors were constructed, the weight of needs of each user group was obtained, and the differentiated design methods were summarized. As a result, a total of 12 hot-selling ovens were selected; a total of 3 minimalist prototypes ABC were obtained, The user group of prototype A is dominated by young women in higher education, prototype B is dominated by middle-aged women in secondary education, and prototype C is dominated by the elderly; a multi-level structure model of user needs was constructed, and The weight of the needs of the 3 user groups were obtained; based on the importance of the needs of each group, the targeted minimalist oven design methods were proposed. Therefore, the method which is based on the theory of multi-level needs and applying the Analytic Hierarchy Process, to construct a multi-level structure model of user needs can clarify the characteristics and design needs of different user groups, and improve the effectiveness and practical significance of the Minimalist Design of the oven. This method can provide a reference for enterprises and designers.

Considerable efforts had been devoted to investigating numerically the droplet impact dynamics on a superhydrophobic surface, whereas most of these numerical simulations were restricted to the two-dimensional (2D) axisymmetric coordinate system with the one-dimensional (1D) substrate surface. In this work, a three-dimensional (3D) computational fluid dynamics (CFD) model, which intergrew a 2D random rough surface, was proposed to investigate the droplet impact dynamics, and the multi-phase flow issue was solved by the Navier–Stokes equations. It is remarkable that the 3D CFD model revealed several significant dynamic details that were not easily captured in a 2D axisymmetric coordinate system or practical experiments. For instance, the 3D CFD model provided a unique perspective to understand the varying dynamic behaviors of impinged droplet in terms of the velocity streamline and dynamic viscosity analyses. Herein, the dynamic viscosity diagram revealed that the sprawl droplet on the 2D random rough surface was classified as the Cassie state, while as the Wenzel state for the smooth surface, which also explained the better bouncing behaviors of the droplet from the random rough surface. Accordingly, we suggested a visual way to evaluate the solid–liquid contact area surrounded by the triple-phase contact line. The effects of finger protrusion and central cavity growth from the sprawl droplet on the vortex generation were further analyzed on the ground of the velocity amplitude distribution and streamline data. The present work can provide early guidance to inquire into the impact dynamics of droplets on the random rough surface.

Chapter 5 - Cell-level modeling of proton exchange membrane fuel cell

Considerable efforts had been devoted to investigating numerically the droplet impact dynamics on a superhydrophobic surface, whereas most of these numerical simulations were restricted to the two-dimensional (2D) axisymmetric coordinate system with the one-dimensional (1D) substrate surface. In this work, a three-dimensional (3D) computational fluid dynamics (CFD) model, which intergrew a 2D random rough surface, was proposed to investigate the droplet impact dynamics, and the multi-phase flow issue was solved by the Navier–Stokes equations. It is remarkable that the 3D CFD model revealed several significant dynamic details that were not easily captured in a 2D axisymmetric coordinate system or practical experiments. For instance, the 3D CFD model provided a unique perspective to understand the varying dynamic behaviors of impinged droplet in terms of the velocity streamline and dynamic viscosity analyses. Herein, the dynamic viscosity diagram revealed that the sprawl droplet on the 2D random rough surface was classified as the Cassie state, while as the Wenzel state for the smooth surface, which also explained the better bouncing behaviors of the droplet from the random rough surface. Accordingly, we suggested a visual way to evaluate the solid–liquid contact area surrounded by the triple-phase contact line. The effects of finger protrusion and central cavity growth from the sprawl droplet on the vortex generation were further analyzed on the ground of the velocity amplitude distribution and streamline data. The present work can provide early guidance to inquire into the impact dynamics of droplets on the random rough surface.

Modeling of the slab heating process in a walking beam reheating furnace for process optimization