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Article
Publication date: 4 July 2008

Colin F. McDonald, Aristide F. Massardo, Colin Rodgers and Aubrey Stone

This paper seeks to evaluate the potential of heat exchanged aeroengines for future Unmanned Aerial Vehicle (UAV), helicopter, and aircraft propulsion, with emphasis placed on…

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Abstract

Purpose

This paper seeks to evaluate the potential of heat exchanged aeroengines for future Unmanned Aerial Vehicle (UAV), helicopter, and aircraft propulsion, with emphasis placed on reduced emissions, lower fuel burn, and less noise.

Design/methodology/approach

Aeroengine performance analyses were carried out covering a wide range of parameters for more complex thermodynamic cycles. This led to the identification of major component features and the establishing of preconceptual aeroengine layout concepts for various types of recuperated and ICR variants.

Findings

Novel aeroengine architectures were identified for heat exchanged turboshaft, turboprop, and turbofan variants covering a wide range of applications. While conceptual in nature, the results of the analyses and design studies generally concluded that heat exchanged engines represent a viable solution to meet demanding defence and commercial aeropropulsion needs in the 2015‐2020 timeframe, but they would require extensive development.

Research limitations/implications

As highlighted in Parts I and II, early development work was focused on the use of recuperation, but this is only practical with compressor pressure ratios up to about 10. For today's aeroengines with pressure ratios up to about 50, improvement in SFC can only be realised by incorporating intercooling and recuperation. The new aeroengine concepts presented are clearly in an embryonic stage, but these should enable gas turbine and heat exchanger specialists to advance the technology by conducting more in‐depth analytical and design studies to establish higher efficiency and “greener” gas turbine aviation propulsion systems.

Originality/value

It is recognised that meeting future environmental and economic requirements will have a profound effect on aeroengine design and operation, and near‐term efforts will be focused on improving conventional simple‐cycle engines. This paper has addressed the longer‐term potential of heat exchanged aeroengines and has discussed novel design concepts. A deployment strategy, aimed at gaining confidence with emphasis placed on assuring engine reliability, has been suggested, with the initial development and flight worthiness test of a small recuperated turboprop engine for UAVs, followed by a larger recuperated turboshaft engine for a military helicopter, and then advancement to a larger and far more complex ICR turbofan engine.

Details

Aircraft Engineering and Aerospace Technology, vol. 80 no. 4
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 16 May 2008

Colin F. McDonald, Aristide F. Massardo, Colin Rodgers and Aubrey Stone

To advance the design of heat exchanged gas turbine propulsion aeroengines utilising experience gained from early development testing, and based on technologies prevailing in the…

3562

Abstract

Purpose

To advance the design of heat exchanged gas turbine propulsion aeroengines utilising experience gained from early development testing, and based on technologies prevailing in the 1970‐2000 time frame.

Design/methodology/approach

With emphasis on recuperated helicopter turboshaft engines, particularly in the 1,000 hp (746 kW) class, detailed performance analyses, parametric trade‐off studies, and overall power plant layouts, based on state‐of‐the‐art turbomachinery component efficiencies and high‐temperature heat exchanger technologies, were undertaken for several engine configuration concepts.

Findings

Using optimised cycle parameters, and the selection of a light weight tubular heat exchanger concept, an attractive engine architecture was established in which the recuperator was fully integrated with the engine structure. This resulted in a reduced overall engine weight and lower specific fuel consumption, and represented a significant advancement in technology from the modified simple‐cycle engines tested in the late 1960s.

Practical implications

While heat exchanged engine technology advancements were projected, there were essentially two major factors that essentially negated the continued study and development of recuperated aeroengines, namely again as mentioned in Part I, the reduced fuel consumption was not regarded as an important economic factor in an era of low‐fuel cost, and more importantly in this time frame very significant simple‐cycle engine performance advancements were made with the use of significantly higher pressure ratios and increased turbine inlet temperatures. Simply stated, recuperated variants could not compete with such a rapidly moving target.

Originality/value

Establishing an engine design concept in which the recuperator was an integral part of the engine structure to minimise the overall power plant weight was regarded as a technical achievement. Such an approach, together with the emergence of lighter weight recuperators of assured structural integrity, would find acceptance around the year 2000 when there was renewed interest in the use of more efficient heat exchanged variants towards the future goal of establishing “greener” aeroengines, and this is discussed in Part III of this paper.

Details

Aircraft Engineering and Aerospace Technology, vol. 80 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 21 March 2008

Colin F. McDonald, Aristide F. Massardo, Colin Rodgers and Aubrey Stone

Interest is currently being expressed in heat exchanged propulsion gas turbines for a variety of aeroengine applications, and in support of this, the aim of this paper is to…

3551

Abstract

Purpose

Interest is currently being expressed in heat exchanged propulsion gas turbines for a variety of aeroengine applications, and in support of this, the aim of this paper is to evaluate the relevance of experience gained from development testing of several recuperated aeroengines in the USA in the late 1960s.

Design/methodology/approach

Technology status, including engine design features, performance, and specific weight of recuperated propulsion gas turbines based on radial and axial turbomachinery, that were development tested in the power range of about 300 to 4,000 hp (224 to 2,984 kW) is discussed in Part I.

Findings

A successful flight worthiness test was undertaken in the USA of a helicopter powered solely by a recuperated turboshaft engine and this demonstrated a specific fuel consumption reduction of over 25 percent compared with the simple‐cycle engine. However; in an era of low‐fuel cost, and uncertainty about the long‐term structural integrity of the high‐temperature heat exchanger, further development work was not undertaken.

Practical implications

The gas turbines tested were based on conventional simple‐cycle engines with essentially “bolted‐on” recuperators. Optimum approaches to minimize engine overall weight were needed in which the recuperator was integrated with the engine structure from the onset of design, and these are discussed in Part II.

Originality/value

Based on engine hardware testing, a formidable technology base was established, which although dated, could provide insight into the technical issues likely to be associated with the introduction of future heat exchanged aeroengines. These are projected to have the potential for reduced fuel burn, less emissions, and lower noise, and recuperated and intercooled turboshaft, turboprop, and turbofan variants are discussed in Part III.

Details

Aircraft Engineering and Aerospace Technology, vol. 80 no. 2
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 August 2008

Peter Rodgers, Colin C. Williams and John Round

The purpose of this paper is to explore the criminal workplace activities of both employers and employees in Ukrainian enterprises. It challenges traditional definitions of…

1104

Abstract

Purpose

The purpose of this paper is to explore the criminal workplace activities of both employers and employees in Ukrainian enterprises. It challenges traditional definitions of corruption and suggests that the practices that can be observed fit into the category of organised crime because of the country's economic framework. The paper also explores how the practices are partially a legacy of Soviet economic processes.

Design/methodology/approach

A total of 700 household surveys were completed in three cities, Kyiv (where 450 surveys were completed), Uzhgorod (150) and Kharkiv (100). To complement these, approximately 25 in‐depth interviews were undertaken with workers in each region. Furthermore, ethnographic observations and “kitchen table” interviews also played an important role in the research. Although the research was oriented towards those working in informal economies, business owners (both formal and informal) were also interviewed.

Findings

As well as revealing the endemic nature of corruption in Ukrainian workplaces and the high levels of informal activity undertaken by workers, the research found that many people wish for their workplace to become more regulated.

Research limitations/implications

Further interviews could have been carried out with state officials and in more locations. The implications are multiple but mainly they demonstrate the difficulty that those charged with economic reform in Ukraine must face.

Originality/value

It is one of the first studies to explore these issues in Ukraine using a variety of research methods.

Details

International Journal of Social Economics, vol. 35 no. 9
Type: Research Article
ISSN: 0306-8293

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Article
Publication date: 3 June 2019

Benjamin Afreh, Peter Rodgers, Natalia Vershinina and Colin C. Williams

The purpose of this paper is to examine the multi-faceted contexts, which influence the motives, decisions and actions that underpin the mundane and lively entrepreneurial…

1189

Abstract

Purpose

The purpose of this paper is to examine the multi-faceted contexts, which influence the motives, decisions and actions that underpin the mundane and lively entrepreneurial practice of migrant youth entrepreneurs (MYEs) within a developing economy context. Moreover, the paper explores the under-researched linkages between migration and informal entrepreneurship.

Design/methodology/approach

Inductive, qualitative field data from a migrant destination, the Ashanti Region in Ghana are analysed, comprising 15 interviews with MYEs who hail from 12 communities in the three Northern Regions of Ghana. The authors introduce a narrative-based approach, which has previously been under-employed within empirical studies of informal entrepreneurship.

Findings

The findings showcase the complex array of opportunities and challenges, which influence individual decisions to engage in informal entrepreneurship. The findings highlight the importance of not only economic rationales but also non-economic rationales for engaging in informal entrepreneurship. Such rationales emerge from the legitimation of informal practices, the social embeddedness of migrant youth within family and community networks and the precarious nature of informal entrepreneurship.

Originality/value

The fine-grained discussion of the findings contributes explicitly to theory by underscoring the diversity of informal entrepreneurship activities. Theoretically, the article demonstrates the need to look beyond narrow economic explanations for why individuals engage in informal entrepreneurship. Taking a more holistic approach to explaining motivations for engaging in informal entrepreneurship, enables more nuanced understandings of the importance of non-economic rationales for individuals, located in specific contextual settings.

Details

International Journal of Entrepreneurial Behavior & Research, vol. 25 no. 5
Type: Research Article
ISSN: 1355-2554

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Article
Publication date: 1 November 2022

Muhammad Shehryar Shahid, Peter Rodgers, Natalia Vershinina, Mashal E. Zehra and Colin C. Williams

Informal entrepreneurship is seen as a direct outcome of either the failure of formal institutions or the asymmetry between formal and informal institutions. These two viewpoints…

397

Abstract

Purpose

Informal entrepreneurship is seen as a direct outcome of either the failure of formal institutions or the asymmetry between formal and informal institutions. These two viewpoints are so far debated as alternative theoretical explanations for the prevalence of informal entrepreneurship. In this paper, the authors offer a theoretically integrative approach to further advance the institutional perspective of informal entrepreneurship. The purpose of this paper is to address these issues.

Design/methodology/approach

Using face-to-face surveys of 322 street entrepreneurs from Lahore, Pakistan, the authors deploy the hitherto unused partial least square approach (PLS) to structural equation modeling (SEM) to analyze data within the field of informal entrepreneurship.

Findings

The empirical findings strongly support the theoretical propositions of the new institutional perspective that the authors present in their paper. The authors find no direct impact of factors like procedural justice, redistributive justice and public sector corruption (i.e. formal institutional failings) on the formalization intentions of street entrepreneurs. Their findings demonstrate that the relationship between formal institutional failings and formalization intentions can only be explained through the mediating role of institutional asymmetry (i.e. tax morality).

Research limitations/implications

From a policy perspective, the authors find that if they can encourage street entrepreneurs to obtain a local-level registration as the first step toward formalization, it will significantly increase their chances to opt for higher national-level registrations.

Originality/value

This paper presents a unique attempt to further understand the context of street entrepreneurship through the theoretical lens of the institutional theory. In doing so, it synthesizes the arguments of existing institutional perspectives and further develops the institutional theory of informal entrepreneurship. Moreover, the paper develops the concept of “formalization intentions”.

Details

International Journal of Entrepreneurial Behavior & Research, vol. 28 no. 8
Type: Research Article
ISSN: 1355-2554

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Book part
Publication date: 16 August 2021

Héctor José Martínez Arboleya

This work is keeping with the increasingly frequent studies that take into account a broader context challenging entrepreneurship as high-growth, technology-driven and venture…

Abstract

This work is keeping with the increasingly frequent studies that take into account a broader context challenging entrepreneurship as high-growth, technology-driven and venture capital-backed process. Addressed comprehensively in the migration studies, Mexicans are examples of those groups who are often ‘invisible’ when attempting to understand the dimension of entrepreneurship, since they are associated more like ‘workers’ than ‘entrepreneurs’. This research presents an exploratory case study of Mexican entrepreneurs in the province of Quebec, Canada context. It is a qualitative analysis using a methodology inspired by the grounded theory. Twenty-three interviews were conducted with Mexican residents of the cities of Montreal, Quebec and Gatineau. The main objective was to initiate a theorisation about the immigrant entrepreneurship phenomenon in a poorly documented group and context. Some conceptual categories were built from the perspective of the migrants themselves. The importance of previous experiences, family support and the reading of the territory to detect business opportunities were relevant. Routes of business entry profiles were detected. In addition, the ethnic positioning category (the social construction that is made in the host society according to the ethnic group to which immigrant entrepreneurs belong) is proposed. This category was a key to shape the structure of opportunity that allows the creation of businesses in the host cities.

Details

Global Migration, Entrepreneurship and Society
Type: Book
ISBN: 978-1-83982-097-7

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Article
Publication date: 29 September 2022

Peter Hooper

This paper aims to present experimental experience of heavy fuelling of a spark ignition crankcase scavenged two-stroke cycle unmanned aerial vehicle (UAV) engine, particularly…

110

Abstract

Purpose

This paper aims to present experimental experience of heavy fuelling of a spark ignition crankcase scavenged two-stroke cycle unmanned aerial vehicle (UAV) engine, particularly focusing on the effects of compression ratio variation, and to cross-correlate with the results of fluid dynamic modelling of the engine and fuels used.

Design/methodology/approach

One-dimensional modelling of the engine has been conducted using WAVE software supported by experimental dynamometer testing of a spark ignition UAV engine to construct a validated computational model using gasoline and kerosene JET A-1 fuels.

Findings

The investigation into the effects of compression ratio variation via fluid dynamic simulation and experimental testing has allowed an assessment of the approach for improving heavy fuel operation of UAV engines using auxiliary transfer port fuel injection. The power level achieved with reduced compression ratio heavy fuel operation is equal to 15.35 kW at 6,500 revolutions per minute compared to 16.27 kW from the standard gasoline engine or a reduction of 5.7%.

Practical implications

The studied engine is specifically designed for UAV applications. The validation of the computational models to explore the effects of compression ratio and heavy fuel injection on the solution and cost is supported by experimental tests.

Originality/value

The application of auxiliary port fuel injection of heavy fuel and associated compression ratio optimisation offers an alternative approach to achieve the safety and logistical challenges of the single fuel policy for UAVs. The application of WAVE to simulate crankcase scavenged two-stroke cycle engines has been applied in very few cases. This study shows further exploratory work in that context.

Details

Aircraft Engineering and Aerospace Technology, vol. 95 no. 4
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 27 July 2012

Colin C. Williams and Peter Rodgers

Contrary to the view that the subsistence economy is some minor residue persisting in only a few peripheral enclaves of modern economies, the purpose of this paper is to begin to…

189

Abstract

Purpose

Contrary to the view that the subsistence economy is some minor residue persisting in only a few peripheral enclaves of modern economies, the purpose of this paper is to begin to chart the importance and prevalence of subsistence work across the contemporary economic landscape and the reasons underpinning engagement in this form of non‐commodified labour.

Design/methodology/approach

To do so, the extent of, and reasons for, subsistence production amongst those living in contemporary Moscow is evaluated using face‐to‐face interviews with 313 households in affluent, mixed and deprived districts.

Findings

It was found that subsistence work is a ubiquitous phenomenon which is relied on heavily by Muscovite households. Until now, those participating in such subsistence work have been portrayed either as rational economic actors, dupes, seekers of self‐identity, or simply doing so out of necessity or choice. Rather than depict one as correct and the others as invalid, this survey inductively generates a theoretically‐integrative approach which differentiates between “willing” (rational economic actors, choice, identity seeking) and “reluctant” (economic and market necessity, dupes) participants in subsistence production.

Research limitations/implications

The paper examines only one city. Further research is now required into the extent of, and reasons for, subsistence production in the rest of Central and Eastern Europe, as well as beyond.

Originality/value

This is one of the first papers to identify and explain the ubiquitous persistence of subsistence work in contemporary economies.

Details

International Journal of Social Economics, vol. 39 no. 9
Type: Research Article
ISSN: 0306-8293

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Article
Publication date: 28 June 2011

Colin C. Williams, Sara Nadin and Peter Rodgers

Since the turn of the millennium, a small corpus of post‐structuralist thought has emerged that challenges the dominant belief that capitalism is now hegemonic and that all…

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Abstract

Purpose

Since the turn of the millennium, a small corpus of post‐structuralist thought has emerged that challenges the dominant belief that capitalism is now hegemonic and that all economic formations are contrasting varieties of capitalism. This paper seeks to contribute to the development of this emergent perspective. The aim is to challenge the notion that the Ukrainian economy can be represented as some variety of capitalism by highlighting the shallow permeation of capitalist practices into daily life and the continuing prevalence of multifarious non‐capitalist economic practices.

Design/methodology/approach

To achieve this, evidence is here reported from a 2005‐6 survey that analysed the extent to which 600 households in Ukraine used capitalist and non‐capitalist economic practices in their coping tactics.

Findings

This reveals not only the limited use of capitalist practices in the everyday coping tactics of households in Ukraine but also how an array of non‐capitalist economic practices remain heavily relied on by a majority of households to secure their livelihood. The outcome is a call to tentatively reject the “varieties of capitalism” system of meaning because of what it excludes, prohibits and denies, and to open up the future of post‐Soviet Ukraine to other possible trajectories than simply some variety of capitalism.

Research limitations/implications

This snapshot survey of the everyday coping practices of households displays only that capitalist practices are not hegemonic and that multifarious economic relations persist and are widespread. It does not show whether or not there is movement towards greater reliance on capitalist practices.

Originality/value

It begins through the presentation of evidence on Ukraine to tentatively challenge the application of a “varieties of capitalism” perspective towards Central and Eastern European economies.

Details

Employee Relations, vol. 33 no. 4
Type: Research Article
ISSN: 0142-5455

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