Heat removal in axial flow high pressure gas turbine

The demand for high power in aircraft gas turbine engines as well as industrial gas turbine prime mover promotes increasing the turbine entry temperature, the mass flow rate and the overall pressure ratio. High turbine entry temperature is however the most convenient way to increase the thrust without requiring a large change in the engine size. This research is focused on improving the internal cooling of high pressure turbine blade by investigating a range of solutions that can contribute to the more effective removal of heat when compared with existing configuration. The role played by the shape of the internal blade passages is investigated with numerical methods. In addition, the application of mist air as a means of enhanced heat removal is studied. The research covers three main area of investigation. The first one is concerned with the supply of mist on to the coolant flow as a mean to enhancing heat transfer. The second area of investigation is the manipulation of the secondary flow through cross-section variation as a means to augment heat transfer. Lastly a combination of a number of geometrical features in the passage is investigated. A promising technique to significantly improve heat transfer is to inject liquid droplets into the coolant flow. The droplets which will evaporate after travelling a certain distance, act as a cooling sink which consequently promote added heat removal. Due to the promising results of mist cooling in the literature, this research investigated its effect on a roughened cooling passage with five levels of mist mass percentages. In order to validate the numerical model, two stages were carried out. First, one single-phase flow case was validated against experimental results available in the open literature. Analysing the effect of the rotational force, on both flow physics and heat transfer, on the ribbed channel was the main concern of this investigation. Furthermore, the computational results using mist injection were also validated against the experimental results available in the literature. Injection of mist in the coolant flow helped achieve up to a 300% increase in the average flow temperature of the stream, therefore in extracting significantly more heat from the wall. The Nusselt number increased by 97% for the rotating leading edge at 5% mist injection. In the case of air only, the heat transfers decrease in the second passage, while in the mist case, the heat transfer tends to increase in the second passage. Heat transfer increases quasi linearly with the increase of the mist percentage when there is no rotation. However, in the presence of rotation, the heat transfers increase with an increase in mist content up to 4%, thereafter the heat transfer whilst still rising does so more gradually. The second part of this research studies the effect of non-uniform cross- section on the secondary flow and heat transfer in order to identify a preferential design for the blade cooling internal passage. Four different cross-sections were investigated. All cases start with square cross-section which then change all the way until it reaches the 180 degree turn before it changes back to square cross-section at the outlet. All cases were simulated at four different speeds. At low speeds the rectangle and trapezoidal cross-section achieved high heat transfer. At high speed the pentagonal and rectangular cross-sections achieved high heat transfer. Pressure loss is accounted for while making use of the thermal performance factor parameter which accounts for both heat transfer and pressure loss. The pentagonal cross-section showed high potential in terms of the thermal performance factor with a value over 0.8 and higher by 33% when compared to the rectangular case. In the final section multiple enhancement techniques are combined in the sudden expansion case, such as, ribs, slots and ribbed slot. The maximum heat enhancement is achieved once all previous techniques are used together. Under these circumstances the Nusselt number increased by 60% in the proposed new design

Citizenship and political participation in the State of Kuwait : the case of National Assembly (1963-1996)

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Defects Associated with Sub-Surface Ground Conditions in Construction Contracts: A Comparative Legal Synthesis of Aspects of Risk Allocation in Kuwaiti, French, and English Law

No structure can be erected without ground support. However, preliminary investigation may offer little protection against sudden surprises. Topographical features are therefore of great significance for construction projects, playing a decisive role in cost estimates. It is necessary for a successful construction design to carry out a sufficient examination of the site, in order to determine the plan area available for proposed works, and the nature of the subsoil with view to deciding the correct design for foundations or methods of the underground working. The present paper purports to elucidate this concept in its legal framework. The plan of campaign in the legal analysis is a comparative one, with particular emphasis on the position of the Kuwaiti, French, and English Law. The purpose is to sketch some of the key questions in this area, and to assess the present state of the law. The discussion reveals that construction contracts essentially take as their standard the strict liability of constructors, ie architect/engineers and contractors; the soil risk is their risk, and their degree of responsibility rises with their technical qualifications. This topic is of particular importance to Middle Eastern and North African countries, in which civil codes draw extensively from their French counterpart. However, although these systems generally enforce a decennial liability scheme, many governments in the region, including Kuwait, has long adopted the FIDIC form for public works contract, albeit with considerable modifications. Statements and opinions as to the law in any jurisdiction should not be taken as definitive. In any particular instance, legal advice should be sought. Keywords: construction law, Kuwaiti law, French law, English law, ground conditions, liability, contract, tort

Effects of mist fractions on heat transfer characteristics in a rotating roughened cooling passage

This paper investigates the effects of the mist fractions on heat transfer characteristics applied on a rotating U-channel with inclined ribs at an angle of 45°. This study has been conducted on five different mist percentages from 1 to 5 with a 1% increment at each step, and all of the cases have been investigated for Reynolds number values of 5000, 10000, 25000 and 40000. The numerical results obtained from the application of RNG k-ε turbulence model with enhanced-wall function were in good agreement with the experimental data of the smooth and ribbed channels both with and without mist addition. Results also demonstrated a 300% increase in the flow temperature difference and a noticeable increase in Nusselt number at each bend region and at the downstream of the leading edge around 25% and 110% respectively, at high mist fraction (5%); when compared with the case where only air was used. With %5 mist addition, the convective efficiency also reaches approximately 69%

Pre-registration nursing students’ experiences of stress

This research study aimed to explore stress among pre-registration nursing students in the United Kingdom. The specific objectives of the study were: To explore the experience of stress among pre-registration nursing students; to determine the type of stress and sources of stress in pre-registration nursing field; to investigate the perceptions of pre-registration nursing students on stress and anxiety in pre-registration nursing programme; and to identify suitable measures that can be implemented to help the pre-registration nursing students to cope with stress. Qualitative research method and phenomenological approach was used in this study and the data was collected with the help of face-to-face semi-structured interviews. The setting for the current study was a higher education institution (HEI) that delivers pre-registration nurse education in the UK. The study sample was six pre-registration nursing students from the East Midlands who were in the first, second, and in final year of the study program leading to BSc (Hons) Nursing with NMC Registration. A thematic analysis of the data was conducted which led to four emergent themes: Pre-registration nursing students’ experiences of stress; re-registration nursing students’ perceptions of stress and anxiety; sources of stress in the nursing field; and measures for coping with stress. The findings revealed that the pre-registration nursing students in this study perceived stress as a problem associated with human health that basically is caused by academic pressure presented by either theoretical assignments, projects, and examinations and placement demands such as while caring for patients. Moreover, stress among pre-registration nursing students was found to be a problem embedded in their lifestyle that impacts their wellbeing. Further findings showed that the study participants perceived that stress and anxiety are interrelated; anxiety takes place in response to stress resulting from academic and clinical placement pressure; and anxiety has a strong relationship with stress and is a contributor to depression too. The study participants also perceived that the major causes of stress include social distress, financial problems, academic pressure, demands of clinical placement, and family expectations. Academic pressure was found to be the most common cause of stress among the pre-registration nursing students in this study. Lastly, the findings revealed that the coping strategies that can help pre-registration nursing students to manage stress are adopting social support mechanisms, encouraging physical activities, and spiritual support. Keywords: Pre-registration nursing students, Stress, Coping. DOI: 10.7176/JHMN/85-14 Publication date: January 31st 202

Future developments and trends in use of picture archiving and communication systems

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University London.Objectives: This study identifies modern information technologies that can improve the clinical practice of Picture Archiving and Communication Systems (PACS) and determines the approaches that are needed to improve the functionality of current PACS to provide better next generation PACS and to improve the future of radiology practices and workflow with future PACS generations. Method: A parallel mixed method approach was adopted including qualitative method (semi-structured interviews), quantitative method (questionnaire survey) and observation of online discussion groups on PACS. Five databases were searched to find salient literature, including Science Direct, Springer Link, Scopus, CINAHL Plus and Google Scholar. Six radiologists were interviewed and questionnaires were collected from 120 radiologists. Four online discussion groups related to PACS were monitored via LinkedIn. The data were analysed thematically using the thematic analysis method. Finally, a focus group was held with a separate group of radiologists to validate the findings. Results: Eight themes emerged from the thematic analysis of the data: (1) limitations of traditional PACS; (2) user needs and requirements that can increase PACS functionality; (3) Web based solutions of PACS; (4) PACS on mobile phones; (5) Vendor Neutral Archive (VNA); (6) full integration of voice recognition in PACS; (7) backup solutions for the system and (8) continuous training for PACS users. Discussion: With the development of healthcare information and communication technology (ICT) and with the increased demands of the radiologists to expand PACS usability, traditional PACS must be updated to follow the changes. Modern technologies can provide better solutions to enhance the functionality of current PACS. The next generation of PACS can fulfil the future requirements of users. This study considers the issues between the needs and requirements of the users of a PACS system in the future and the developing solutions in ICT and the PACS industry. Moreover, highly developed PACS systems with advanced features will have a direct impact in changing and improving radiology workflow. Accordingly, a model has been developed that proposes new features for the next generation PACS system, which may be applied to the next generation radiology practice. The model was validated with the focus group and, by using a separate group of radiologists in another country, was determined to be generalisable. Conclusion: It is widely recognised that traditional PACS must be updated to adopt recent advances in ICT. This research has identified themes that, when incorporated, will enhance the functionality of PACS and radiology workflow and provide better quality clinical practice. The findings from this empirical research can be used: as recommendations to vendors; for technology development; and by medical institutes to consider aspects when undertaking implementation of PACS and training future radiologists. Keywords: 'Picture archiving and communication system’, PACS, Future trends, next generation, Organisational efficiency, Productivity, Clinical practice, Ubiquitous.Ministry of Health, Government of Kuwai

Civic Engagement among Middle Eastern and North African Refugees and Immigrants

This research explored the attitudes toward, frequency and predictors of civic engagement among the Middle East and North Africa (MENA) immigrants and refugees. Respondents (n=106) reported strongly positive attitudes and engaged in various civic activities. Attitudes were found as main predictor for level of civic engagement

Mechanical property evaluation of an Al-2024 alloy subjected to HPT processing

An aluminum-copper alloy (Al-2024) was successfully subjected to high-pressure torsion (HPT) up to five turns at room temperature under an applied pressure of 6.0 GPa. The Al-2024 alloy is used as a fuselage structural material in the aerospace sector. Mechanical properties of the HPT-processed Al-2024 alloy were evaluated using the automated ball indentation technique. This test is based on multiple cycles of loading and unloading where a spherical indenter is used. After two and five turns of HPT, the Al-2024 alloy exhibited a UTS value of ~1014 MPa and ~1160 MPa respectively, at the edge of the samples. The microhardness was measured from edges to centers for all HPT samples. These results clearly demonstrate that processing by HPT gives a very significant increase in tensile properties and the microhardness values increase symmetrically from the centers to the edges. Following HPT, TEM examination of the five-turn HPT sample revealed the formation of high-angle grain boundaries and a large dislocation density with a reduced average grain size of ~80 nm. These results also demonstrate that high-pressure torsion is a processing tool for developing nanostructures in the Al-2024 alloy with enhanced mechanical propertie

Habitat productivity is a poor predictor of body size in rodents

The “resource availability hypothesis” predicts occurrence of larger rodents in more productive habitats. This prediction was tested in a dataset of 1,301 rodent species. We used adult body mass as a measure of body size and normalized difference vegetation index (NDVI) as a measure of habitat productivity. We utilized a cross-species approach to investigate the association between these variables. This was done at both the order level (Rodentia) and at narrower taxonomic scales. We applied phylogenetic generalized least squares (PGLS) to correct for phylogenetic relationships. The relationship between body mas and NDVI was also investigated across rodent assemblages. We controlled for spatial autocorrelation using generalized least squares (GLS) analysis. The cross-species approach found extremely low support for the resource availability hypothesis. This was reflected by a weak positive association between body mass and NDVI at the order level. We find a positive association in only a minority of rodent subtaxa. The best fit GLS model detected no significant association between body mass and NDVI across assemblages. Thus, our results do not support the view that resource availability plays a major role in explaining geographic variation in rodent body size