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Article
Publication date: 1 January 1987

M.G.M.S. Carvalho, D.F.G. Durão and J.C.F. Pereira

A three‐dimensional computer simulation of a combustion chamber used in the glass production industry is presented. A numerical solution technique is used to solve the governing…

143

Abstract

A three‐dimensional computer simulation of a combustion chamber used in the glass production industry is presented. A numerical solution technique is used to solve the governing time‐averaged partial differential equation and the physical modelling for turbulence, combustion and thermal radiation. A two‐equation turbulence model is employed along with a combustion model based on a fast kinetics statistical approach. A radiation model is used along with the Hottel mixed grey gas model. To solve the governing differential equations an implicit technique of finite‐difference kind is applied. The economy of the computations is very considerably enhanced by the separate calculation of the burner and bulk glass combustion chamber regions, in a manner which takes account of the differing physical nature of their flows. The burner outlet region is calculated with an axisymmetric model. Such two‐dimensional calculations allowed a good resolution of the burner outlet, and provide the inlet conditions for the three‐dimensional calculations of the glass furnace. The prediction procedure is applied to an industrial glass furnace, which operates with oxy‐fuel conditions. Measurements of mean gas temperature and concentrations were performed at different locations in the furnace. The calculated flame length, temperature field and concentrations are with satisfactory agreement with the measured ones.

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Engineering Computations, vol. 4 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 December 2000

Jaime Alvarez, Mirko Pap and Alvaro Valencia

This work numerically investigates the effects of two square bars placed in various arrangements in a channel on pressure drop and heat transfer. Tandem arrangements and the two…

550

Abstract

This work numerically investigates the effects of two square bars placed in various arrangements in a channel on pressure drop and heat transfer. Tandem arrangements and the two bars arranged side by side to the approaching flow are considered. The separation distance between the bars is varied in both types of arrangements. The Reynolds number Re based on channel height is 104, whereas the bar height to channel height (d/H) is 0.152. The channel walls are subjected to a constant wall temperature. The k‐ε turbulence model was used in conjunction with the Reynolds‐averaged momentum and energy equations for the simulations. A finite volume technique with staggered grids combined with the SIMPLEC algorithm is applied with a fine grid resolution. Results show that the local and global Nusselt numbers on the channel walls are strongly increased by the unsteady vortex shedding induced by the bars.

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International Journal of Numerical Methods for Heat & Fluid Flow, vol. 10 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 May 2007

David Fátima and Rute Abreu

The purpose of this paper is to discuss the implementation and developments of the Bologna Process in the Higher Education Institutions (HEIs) as a new paradigm of the European…

405

Abstract

Purpose

The purpose of this paper is to discuss the implementation and developments of the Bologna Process in the Higher Education Institutions (HEIs) as a new paradigm of the European system of higher education, in general, and of the Portuguese system, in particular.

Design/methodology/approach

The paper uses firstly, higher education system statistics; secondly, Government and European Union documents; and thirdly, academic papers that conceptual frame the issues under discussion.

Findings

Portuguese HEIs are engaged in the Bologna process, but it shows some contradictions within the higher education system. One of these contradictions is the restructuring of the degrees and cycles had led to the apparently destruction of the binary system (universities and polytechnics) which existed in for more than 30 years. Another contradiction is carry out common European priorities and, at the same time, maintaining the national culture, language, education systems and HEIs autonomy. Although, the system promotes the cooperation between HEIs and increases the research, the innovation and the sustainable development, at a national level, as well as, an international level.

Practical implications

HEIs need to promote the strategic function of higher education and it demands a constant adaptation of the conceptual field, especially, in the social, economic and technological perspectives. These perspectives will assurance the enhancement and the preservation of quality of teaching/learning. These will improve the education for sustainable development that it develops higher growth and better educational performance.

Originality/value

Provides empirical evidence about the social dimension of the higher education system and analyse the Bologna Process in the HEIs.

Details

Social Responsibility Journal, vol. 3 no. 2
Type: Research Article
ISSN: 1747-1117

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Article
Publication date: 5 March 2018

Kannan B.T. and Panchapakesan N.R.

This study aims to investigate the effects of nozzle momentum flux distribution on the flow field characteristics.

143

Abstract

Purpose

This study aims to investigate the effects of nozzle momentum flux distribution on the flow field characteristics.

Design/methodology/approach

The nozzle configuration consists of a central nozzle surrounded by four nozzles. All nozzles have the same diameter and constant separation between nozzles. OpenFOAM® is used for simulating the jet flow. Reynolds-averaged Navier-Stokes (RANS) equations are solved iteratively with a first-order closure for turbulence. Pitot-static tube with differential pressure transducer is used for mean velocity measurements. The comparison of computed results with experimental data shows similar trend and acceptable validation.

Findings

According to the results, the momentum flux distribution significantly alters the near field of multiple turbulent round jets. Highly non-linear decay region in the near field is found for the cases having higher momentum in the outer jets. As a result of merging, increased positive pressure is found in the mixing region. Higher secondary flows and wider mixing region are reported as a result of momentum transfer from axial to lateral directions by Reynolds stresses.

Research limitations/implications

The present study is limited to isothermal flow of air jet in air medium.

Social implications

Optimum momentum flux distribution in multijet injector of a combustor can reap better mixing leading to better efficiency and lesser environmental pollution.

Originality/value

As summary, the contributions of this paper in the field of turbulent jets are following: simulations for various momentum distribution cases have been performed. In all the cases, the flow at the nozzle exit is subsonic along with constant velocity profile. To simulate proper flow field, a large cylinder-type domain with structured grid is used with refinements toward the nozzle exit and jet axis. The results show that the non-linearity increases with increase in momentum of outer jets. Longer merging zones are reported for cases with higher momentum in outer nozzles using area-averaged turbulent kinetic energy. Similarly, wider mixing regions are reported using secondary flow parameter and visualizations.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 2
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 1 December 2001

Yanhu Guo, Guangbin He and Andrew T. Hsu

Proposes the use of genetic algorithms to assist the development of turbulence models. A variable Schmidt number model for scalar mixing in jet‐in‐crossflows was developed through…

420

Abstract

Proposes the use of genetic algorithms to assist the development of turbulence models. A variable Schmidt number model for scalar mixing in jet‐in‐crossflows was developed through theoretical analyses. A uniform micro genetic algorithm is implemented to optimize the model. This is the first known application of the genetic algorithm (GA) technique to turbulence model development. Overall, the GA technique worked exceptionally well for this problem in a cost‐effective and time‐efficient manner. A set of experimental data on a single round jet issued into a confined crossflow is selected for calibration and optimization of the model constants using the uniform micro‐genetic optimization algorithm. Three sets of experimental data of jet‐in‐crossflows are used for the validation of the new model. Numerical results show that the proposed scheme of using the genetic algorithms to develop turbulence models produces very promising results.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 11 no. 8
Type: Research Article
ISSN: 0961-5539

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Book part
Publication date: 8 September 2023

Payal Kumar

Abstract

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Gender Equity in Hospitality: The Case of India
Type: Book
ISBN: 978-1-80382-666-0

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Gender and Tourism
Type: Book
ISBN: 978-1-80117-322-3

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Article
Publication date: 30 September 2020

Gökhan Sur and Ömer Erkan

Drilling of carbon fiber reinforced plastic (CFRP) composite plates with high surface quality are of great importance for assembly operations. The article aims to optimize the…

385

Abstract

Purpose

Drilling of carbon fiber reinforced plastic (CFRP) composite plates with high surface quality are of great importance for assembly operations. The article aims to optimize the drill geometry and cutting parameters to improve the surface quality of CFRP composite material. In this study, CFRP plates were drilled with uncoated carbide drill bits with standard and step geometry. Thus, the effects of standard and step drill bits on surface quality have been examined comparatively. In addition, optimum output parameters were determined by Taguchi, ANOVA and multiple decision-making methods.

Design/methodology/approach

Drill bit point angles were selected as 90°, 110° and 130°. In cutting parameters, three different cutting speeds (25, 50 and 75 m/min) and three different feeds (0.1, 0.15 and 0.2 mm/rev) were determined. L18 orthogonal sequence was used with Taguchi experimental design. Three important output parameters affecting the surface quality are determined as thrust force, surface roughness and delamination factor. For each output parameter, the effects of drill geometry and cutting parameters were evaluated. Input parameters affecting output parameters were analyzed using the ANOVA method. Output parameters were estimated by creating regression equations. Weights were determined using the analytic hierarchy process (AHP) method, and multiple output parameters were optimized using technique for order preference by Similarity to An ideal solution (TOPSIS).

Findings

It has been determined from the experimental results that step drills generate smaller thrust forces than standard drills. However, it has been determined that it creates greater surface roughness and delamination factor. From the Taguchi analysis, the optimum input parameters for Fz step tool geometry, 90° point angle, 75 m/min cutting speed and 0.1 mm/rev feed. For Fd, are standard tool geometry, 90° point angle, 25 m/min cutting speed and 0.1 mm/rev feed and for Ra, are standard tool geometry, 130° point angle, 25 m/min cutting speed and 0.1 mm/rev feed. ANOVA analysis determined that the most important parameter on Fd is the tip angle, with 56.33%. The most important parameter on Ra and Fz was found to be 40.53% and 77.06% tool geometry, respectively. As a result of the optimization with multiple criteria decision-making methods, the test order that gave the best surface quality was found as 4–1-9–5-8–17-2–13-6–16-18–15-11–10-3–12-14. The results of the test number 4, which gives the best surface quality, namely, the thrust force is 91.86 N, the surface roughness is 0.75 µm and the delamination factor is 1.043. As a result of experiment number 14, which gave the worst surface quality, the thrust force was 149.88 N, the surface roughness was 3.03 µm and the delamination factor was 1.163.

Practical implications

Surface quality is an essential parameter in the drilling of CFRP plates. Cutting tool geometry comes first among the parameters affecting this. Therefore, different cutting tool geometries are preferred. A comparison of these cutting tools is discussed in detail. On the other hand, thrust force, delamination factor and surface roughness, which are the output parameters that determine the surface quality, have been optimized using the TOPSIS and AHP method. In this way, this situation, which seems complicated, is presented in a plain and understandable form.

Originality/value

In the experiments, cutting tools with different geometries are included. Comparatively, its effects on surface quality were examined. The hole damage mechanism affecting the surface quality is discussed in detail. The results were optimized by evaluating Taguchi, ANOVA, TOPSIS and AHP methods together.

Details

Engineering Computations, vol. 38 no. 5
Type: Research Article
ISSN: 0264-4401

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Tourism Innovation in the Digital Era
Type: Book
ISBN: 978-1-83797-166-4

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Article
Publication date: 12 September 2016

Carlos Costa, Zelia Breda, Fiona Eva Bakas, Marilia Durão and Isabel Pinho

This paper aims to investigate the ways in which gender influences entrepreneurial motivations and barriers in the Brazilian tourism sector. As an economic process, tourism…

1018

Abstract

Purpose

This paper aims to investigate the ways in which gender influences entrepreneurial motivations and barriers in the Brazilian tourism sector. As an economic process, tourism entrepreneurship is widely spread in Brazil, with tourism development programs promoting it as a strategy to empower women, however limited research exists on how gender roles influence entrepreneurial ideals. This nationwide study aims to provide a contemporary insight into how tourism entrepreneurs in Brazil are situated within current entrepreneurship theorizing by questioning the complexity caused as gender roles influence entrepreneurial conceptualizations of what constitute motivations and barriers.

Design/methodology/approach

This study uses online questionnaires aimed, for the first time, at a large variety of tourism sub-sectors in Brazil. Having nation-wide scope, the questionnaires produce knowledge on what motivates and what constrains Brazilian tourism entrepreneurs through a gender lens. Quantitative analysis using SPSS statistical software tests the statistical significance of results and is complemented by the integration of feminist economic theories into the analytical framework.

Findings

The current study’s findings highlight the invisibility of gender’s workings, as the majority of participants did not conceive gender as playing a role in their entrepreneurial experience. Entrepreneurial motivations and barriers show a departure from past literature, such as the fact that similar numbers of male and female tourism entrepreneurs perceive networking as a significant entrepreneurial barrier. This and other interesting findings prompt for alternative conceptualizations of discourses surrounding women’s involvement in tourism entrepreneurship.

Originality/value

This study consists of an original contribution to knowledge on tourism entrepreneurship in Brazil as this is the first time an empirical study has been made on a nation-wide scale regarding the role of gender in Brazilian tourism entrepreneurs’ motivations and constraints.

Details

International Journal of Gender and Entrepreneurship, vol. 8 no. 3
Type: Research Article
ISSN: 1756-6266

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