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Article
Publication date: 26 October 2012

M. Tutar and Ü. Sönmez

The purpose of this paper is to numerically study inflow turbulence effects on the transitional flow in a high pressure linear transonic turbine at the design incidence.

277

Abstract

Purpose

The purpose of this paper is to numerically study inflow turbulence effects on the transitional flow in a high pressure linear transonic turbine at the design incidence.

Design/methodology/approach

The three‐dimensional (3‐D) compressible turbulent flow in a turbine inlet guide vane is simulated using a finite volume based fluid solver coupled with dynamic large eddy simulation (LES) computations to investigate the effects of varying inflow turbulence length scale and the turbulence intensity on the aero‐thermal flow characteristics and the laminar‐turbulent transition phenomena. The computational analyses are extended to very high exit Reynolds number flow conditions to further study the effect of high exit Reynolds numbers on the transitional behavior of the present flow around the inlet guide vane cascades of the turbine. The calculations are performed with varying degree of inflow turbulence intensity values ranging from 0.8 to 6 percent and the inflow turbulence length scales ranging from one to five percent of pitch for different exit isentropic Mach and Reynolds numbers.

Findings

The numerical predictions in comparison with the experimental data demonstrate that the level of inflow turbulence closure provided by the present LES computations offers a reliable framework to predict complex turbulent flow and transition phenomena in high free‐stream turbulence environments of high pressure linear turbines.

Originality/value

This is the first instance in which both artificially modified random flow generation method in association with the dynamic procedure of LES application is employed to represent the realistic inflow turbulence conditions in the high pressure turbine and to resolve the transitional flow in a dynamic approach.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 8
Type: Research Article
ISSN: 0961-5539

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Book part
Publication date: 18 April 2017

Cem Emrence and Aysegul Aydin

Reactive groups adopt a variety of repertoires ranging from institutional resistance to violence to counter mobilizing efforts of movements. Countermovement studies provide useful…

Abstract

Reactive groups adopt a variety of repertoires ranging from institutional resistance to violence to counter mobilizing efforts of movements. Countermovement studies provide useful insights into how violence by non-state actors can constrain social movements’ success. Few studies however considered the possibility that violence may, on the contrary, facilitate the outcomes sought by the movement. Under what conditions do political killings of movement members affect support for the movement? To answer this question, we follow the evolution of the Kurdish ethnic movement in Turkey as a movement party and track changes in the movement’s constituency in response to countermovement violence (1991–2002). The study uses an original dataset of countermovement killings by the ethnic movement’s Islamist rival, Hizbullah, across 113 districts in 13 southeastern provinces. We demonstrate that countermovement violence has non-uniform effects on electoral support for the movement party. These effects are conditional on initial movement strength: in localities with prior loyalties to the ethnic movement, Hizbullah-inflicted harm consolidates the movement party’s constituency. By contrast, countermovement violence is met with reduced support where the movement is weak and is struggling to make inroads to the community. Our findings suggest that initial preferences might play important roles in understanding movement outcomes.

Details

Non-State Violent Actors and Social Movement Organizations
Type: Book
ISBN: 978-1-78714-190-2

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Book part
Publication date: 14 December 2023

Kübra Şimşek Demirbağ

In this study, workplace spirituality is discussed in the context of remote work and the COVID-19 pandemic. First, the focus is on the changes in the meaning and function of…

Abstract

In this study, workplace spirituality is discussed in the context of remote work and the COVID-19 pandemic. First, the focus is on the changes in the meaning and function of employees in the organization during the evolutionary process of industrialization and management paradigms. Afterward, conceptual frameworks for spirituality and workplace spirituality are presented, and in the last section, academic studies that deal with workplace spirituality with distance or hybrid work arrangements are included. Early studies offer insights and recommendations on conceptualizing, developing, and managing workplace spirituality. They all emphasize that spirituality is necessary for remote work as a tool to overcome stress and mental health problems and increase employee well-being. Unfortunately, the remote work and workplace spirituality literature is relatively narrow and needs to be expanded.

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Book part
Publication date: 9 November 2023

Rahman El Junusi, Heru Sulistyo, Fadjar Setiyo Anggraeni and Ferry Khusnul Mubarok

This study aims to examine the relationship between Achievement Motivation (AM), Smart Work (SW), and human resources (HR) performance. It questions how moral global leadership…

Abstract

This study aims to examine the relationship between Achievement Motivation (AM), Smart Work (SW), and human resources (HR) performance. It questions how moral global leadership (MGL) could moderate the relationship between AM, SW, and HR performance. A theoretical model was developed and tested on sample data representing 219 employees, educators, and educational staff of Islamic Higher education (IHE). The data were collected through surveys and applied to structural equation modeling using SEM-PLS. This study found that AM and SW significantly affect HR performance. While MGL substantially moderates the relationship between AM, SW, and HR performance. This study contributes to the literature on MGL, AM, and SW in creating HR performance that has yet to be studied so far. This study offers the concept of MGL, which plays a central role in moderating the relationship between AM, SW, and HR performance.

Details

Macroeconomic Risk and Growth in the Southeast Asian Countries: Insight from Indonesia
Type: Book
ISBN: 978-1-83797-043-8

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Article
Publication date: 13 October 2022

Zeynep Özgüner, Mert Özgüner and Yakup Durmaz

The purpose of this study is to evaluate the effects of COVID-19 on the Turkish manufacturing sector by using analytical hierarchy process (AHP) and Technique for Order Preference…

342

Abstract

Purpose

The purpose of this study is to evaluate the effects of COVID-19 on the Turkish manufacturing sector by using analytical hierarchy process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods on a sectoral basis. In this way, the sectors that had the highest negative effects of COVID-19 will be determined. Thanks to the findings to be obtained as a result of this study, it will be possible for decision-makers to develop strategies that may differ on a sectoral basis at the point of combating the pandemic.

Design/methodology/approach

The negative effects of COVID-19 were revealed by a large literature search. The importance levels of the factors determined within the scope of finance, supply, production and workforce were determined by the AHP method. Then, the TOPSIS method was used to determine which sectors were more affected by the COVID-19 pandemic, based on these factors.

Findings

The findings of this study obtained reveal that the most important negative effect of COVID-19 was on businesses in terms of reduced sales caused by domestic sales and export. Again, the findings show that the sector most affected by COVID-19 is automotive, which shows that the least affected sector is the pharmaceutical and medical equipment sector.

Practical implications

Primary data was used to determine the criteria weight. Therefore, there is a possibility that the answers are not objectively evaluated. The findings are limited to the criteria that was used, the views of the professionals and AHP-TOPSIS methods. Studies that use more criteria and different decision-making methods can have different results.

Originality/value

The manufacturing sector is at the forefront of the sectors affected by the global bottleneck caused by COVID-19. In this study, the effects of the COVID-19 pandemic on the Turkish manufacturing sector are discussed on a sectoral basis. Studies in the literature have revealed that the effects of pandemics such as COVID-19 vary between sectors. For this reason, it is important to evaluate the effects of COVID-19 from a sectoral perspective. Thanks to this study, it is thought that it will be possible to take measures that may differ between sectors to combat the negative effects of COVID-19.

Details

Journal of Business & Industrial Marketing, vol. 38 no. 7
Type: Research Article
ISSN: 0885-8624

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Article
Publication date: 16 September 2013

Jules Voguelin Simo Tala, Serge Russeil, Daniel Bougeard and Jean-Luc Harion

In finned-tube heat exchangers, the array of tubes generates three-dimensional vortices at fin-tube junctions. Theses vortices known as horseshoe vortex (HSV) system are…

366

Abstract

Purpose

In finned-tube heat exchangers, the array of tubes generates three-dimensional vortices at fin-tube junctions. Theses vortices known as horseshoe vortex (HSV) system are responsible of flow mixing and heat transfer increase. The purpose of this paper is to focus on the effect of the fin spacing on the formation, the spatial evolution and dissipation of the HSV system at fin-tube junctions in a two-rows finned-tube heat exchanger. The global characterisation of the heat exchanger performance is also presented.

Design/methodology/approach

The flow structure is numerically analysed through the use of computational fluid dynamics tools. The different vortices of the HSV system are highlighted and quantitatively analysed at each fin-tube junction with vorticity, wall shear stress analysis and two-dimensional streamline plots around tubes.

Findings

The results show that the primary and secondary vortices of the HSV system have antagonistic behaviors with respect to the azimuthal angle variation. The optimum fin spacing ratio E/D that generates the most intense first primary vortex in the HSV system lies between 0.20 and 0.25. Similar observation are made on the thermalhydraulic performance of the heat exchanger as j/f exhibits a maximum value for a fin spacing ratio E/D=0.25.

Research limitations/implications

A detailed URANS simulation shows that even if the flow remains steady in the core of the heat exchanger, unsteady behavior is noticed in the wake of the second tube.

Originality/value

In this study, the flow topology is quantitatively analysed in successive radial planes around heat exchanger tubes. The strong effect of the fin spacing on the HSV generation and dissipation is deeply analysed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 23 no. 7
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 29 August 2019

Bo Zhang, Xiaoqing Qiang, Shaopeng Lu and Jinfang Teng

The purpose of this paper is to numerically investigate the effect of guide vane unsteady passing wake on the rotor blade tip aerothermal performance with different tip clearances.

299

Abstract

Purpose

The purpose of this paper is to numerically investigate the effect of guide vane unsteady passing wake on the rotor blade tip aerothermal performance with different tip clearances.

Design/methodology/approach

The geometry and flow conditions of the first stage of GE-E3 high-pressure turbine have been used to obtain the blade tip three-dimensional heat transfer characteristics. The first stage of GE-E3 high-pressure turbine has 46 guide vanes and 76 rotor blades, and the ratio of the vane to the blade is simplified to 38:76 to compromise the computational resources and accuracy. Namely, each computational domain comprises of one guide vane passage and two rotor blade passages. The investigations are conducted at three different tip gaps of 1.0, 1.5 and 2.0 per cent of the average blade span.

Findings

The results show that the overall discrepancy of the heat transfer coefficient between steady results and unsteady time-averaged results is quite small, but the dramatic growth of the instantaneous heat transfer coefficient along the pressure side is in excess of 20 per cent. The change of the aerothermal performance is mainly driven by turbulence-level fluctuations of the unsteady flow field within gap regions. In addition, the gap size expansion has a marginal impact on the variation ratio of tip unsteady aerothermal performances, even though it has a huge influence on the leakage flow state within the tip region.

Originality/value

This paper emphasizes the change ratio of unsteady instantaneous heat transfer characteristics and detailed the mechanism of blade tip unsteady heat transfer coefficient fluctuations, which provide some guidance for the future blade tip design and optimization.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 14 August 2019

Sultan Ghaleb Aldaihani

The purpose of this paper is to identify administrative empowerment and job satisfaction levels among Kuwait University staff. The study also aimed to reveal the relationship…

960

Abstract

Purpose

The purpose of this paper is to identify administrative empowerment and job satisfaction levels among Kuwait University staff. The study also aimed to reveal the relationship between administrative empowerment and job satisfaction. In addition, the study sought to identify any statistically significant differences in the study sample responses regarding employees’ administrative empowerment and job satisfaction attributed to the study variables (gender and years of experience). Finally, the study sought to identify the possibility of predicting job satisfaction level among Kuwait University staff through administrative empowerment.

Design/methodology/approach

The study sample consisted of 115 administrators chosen from different faculties at Kuwait University. The study used a PLS-SEM via SMARTPLS version 3.2.8 depending on questionnaires as the study’s tools.

Findings

The results revealed that Kuwait University staff enjoyed medium administrative empowerment levels. On the other hand, they had higher job satisfaction levels. It found a statistically positive correlation between job satisfaction and administrative empowerment. The study has found significant associations of administrative empowerment, participation in decision making, group work and self-motivation with job satisfaction.

Originality/value

The study recommends identifying regulatory obstacles that could prevent the dissemination and resolution of empowerment policy and culture.

Details

Journal of Applied Research in Higher Education, vol. 12 no. 2
Type: Research Article
ISSN: 2050-7003

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Article
Publication date: 25 July 2024

Trilok G., N. Gnanasekaran and Moghtada Mobedi

Despite the reputation of the metal-based porous media for their ability to augment heat transfer as widely witnessed in the literature and practically operating heat exchanging…

52

Abstract

Purpose

Despite the reputation of the metal-based porous media for their ability to augment heat transfer as widely witnessed in the literature and practically operating heat exchanging applications, the coexisting penalty of the increased pressure drop demanding increased pumping power poses a major concern that invites the need for an alternate solution to handle this unsought outcome. Therefore, this study aims at providing a better solution to the existing cost and benefit scenarios to benefit a plethora of engineering applications including energy transfer, energy storage and energy conversion.

Design/methodology/approach

This work highlights on the property of stacked woven wire mesh porous media such as their stacking types, porous conditions and thickness scenarios that can potentially result in distinct trade-off scenarios. A vertical channel is numerical modelled by using REV scaled modelling technique using Darcy-Forchheimer and local thermal non-equilibrium models to illustrate the possibilities of this variety of trade off scenarios between the desirable heat transfer and the unsought flow resistance.

Findings

This work illustrates the advantages of wire mesh-based porous medium and its distinct potential in controlling the existing trade-offs between the cost and benefit aspects. It is found that by varying the features of wire mesh porous media, the interplay between the conflictingly existing characteristics can be much easily handled specific to distinct requirements associated with variety of engineering applications.

Originality/value

The study emphasizes on a new solution or methodology to handle the penalty of pressure drop associated with metal-based porous media. Through this study, a novel approach to control the ultimately costing pumping power at the benefit of increased heat transfer is provided considering various requirements that could be associated with any thermal management systems. Various possibilities and potentials of wire mesh porous media are illustrated highlighting on their benefit of ease with which the mentioned goals can be achieved.

Details

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

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Article
Publication date: 24 October 2023

Hasan Tutar, Mehmet Şahin and Teymur Sarkhanov

The lack of a definite standard for determining the sample size in qualitative research leaves the research process to the initiative of the researcher, and this situation…

1137

Abstract

Purpose

The lack of a definite standard for determining the sample size in qualitative research leaves the research process to the initiative of the researcher, and this situation overshadows the scientificity of the research. The primary purpose of this research is to propose a model by questioning the problem of determining the sample size, which is one of the essential issues in qualitative research. The fuzzy logic model is proposed to determine the sample size in qualitative research.

Design/methodology/approach

Considering the structure of the problem in the present study, the proposed fuzzy logic model will benefit and contribute to the literature and practical applications. In this context, ten variables, namely scope of research, data quality, participant genuineness, duration of the interview, number of interviews, homogeneity, information strength, drilling ability, triangulation and research design, are used as inputs. A total of 20 different scenarios were created to demonstrate the applicability of the model proposed in the research and how the model works.

Findings

The authors reflected the results of each scenario in the table and showed the values for the sample size in qualitative studies in Table 4. The research results show that the proposed model's results are of a quality that will support the literature. The research findings show that it is possible to develop a model using the laws of fuzzy logic to determine the sample size in qualitative research.

Originality/value

The model developed in this research can contribute to the literature, and in any case, it can be argued that determining the sample volume is a much more effective and functional model than leaving it to the initiative of the researcher.

Details

Qualitative Research Journal, vol. 24 no. 3
Type: Research Article
ISSN: 1443-9883

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