Browsing by Author "Ogaji, S."
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Item Open Access Advanced low carbon power systems - the advanced zero emissions power plant(Cranfield University, 2009-10) Pagone, Emanuele; Ogaji, S.The global warming issue is becoming more and more important in the public opinion, because its effects on everyday life of the entire mankind are starting to become appreciable. On the next (2009) December will be held in Copenhagen the fifteenth United Nations Climate Change Conference which is expected to be crucial for the future choices to deal with the anthropogenic greenhouse gases issue. The power generation sector is one of the most important contributors to the emissions of greenhouse gases (of which the carbon dioxide is the main anthropogenic example), and it is facing in the last decades a problem that will exacerbate surely the already alarming effect on the global warming: the rapid increase of the world power demand. For these reasons the carbon capture topic is gaining nowadays a lot of attention, especially in the industrial sector, since it will be a strategic field for the power generation in the short-medium term. In fact, it is really likely that will be introduced soon a so-called “cap and trade” system, with the trading of pollution licences related to the CO2 emissions, as the USA president Obama has recently proposed to the Congress. This option would turn out in a completely new scenario in the power generation sector with novel, cleaner concepts being economically more attractive than the conventional ones. This project investigates the performance of a novel thermodynamic cycle with carbon capture, called Advanced Zero Emissions Power plant (AZEP), which has been analysed in the open literature just partially and superficially up to now. Since this project is part of a bigger one in which several carbon capture novel cycles options will be compared, the main objective is to provide a flexible, modular, modern computational tool, called eAZEP, developed from scratch. The second objective is the evaluation of the four main layouts of the AZEP concept as a stand alone power plant, assessing their inclination to be included in an unfired combined cycle featured with an Heat Recovery Steam Generator (HRSG). A final, third objective is the development of a routine for the off-design performance calculation to be included in on old pre-existing computational tool. The original contribution of this work to the knowledge on the topic comprises 1. the conception of two new layouts for the AZEP cycle (the Post Expan-sion Heat exchanger layouts); 2. the performance evaluation of the long term potential for the power plant; 3. a sensitivity analysis of the thermodynamic concept. The best suitable arrangements of the plant layout are identified together with the main parameters which influence their performance, both for the combined cycle perspective implementation and for the stand alone option. Thanks to the flexibility of eAZEP will be easy to consider, in a future work, a pretty wide number of alternative concepts and investigate more cycle parameters in order to broaden the conclusions obtained in this work. Moreover the combined cycle off-design new routine must be debugged and validated.Item Open Access Multi-disciplinary conceptual design of future jet engine systems(Cranfield University, 2010-04) Kyprianidis, Konstantinos G.; Ogaji, S.; Singh, R.This thesis describes various aspects of the development of a multi-disciplinary aero engine conceptual design tool, TERA2020 (Techno-economic, Environmental and Risk Assessment for 2020), based on an explicit algorithm that considers: engine performance, engine aerodynamic and mechanical design, aircraft design and performance, emissions prediction and environmental impact, engine and airframe noise, and production, maintenance and direct operating costs. As part of this research e ort, a newly-derived semi-empirical NOx correlation for modern rich-burn single-annular combustors is proposed. The development of a numerical methods library is also presented, including an improved gradientbased algorithm for solving non-linear equation systems. Common assumptions made in thermo- uid modelling for gas turbines and their e ect on caloric properties are investigated, while the impact of uncertainties on performance calculations and emissions predictions at aircraft system level is assessed. Furthermore, accuracy limitations in assessing novel engine core concepts as imposed by current practice in thermo- uid modelling are identi ed. The TERA2020 tool is used for quantifying the potential bene ts from novel technologies for three low pressure spool turbofan architectures. The impact of failing to deliver speci c component technologies is quanti ed, in terms of power plant noise and CO2 emissions. To address the need for higher engine thermal e ciency, TERA2020 is again utilised; bene ts from the potential introduction of heat-exchanged cores in future aero engine designs are explored and a discussion on the main drivers that could support such initiatives is presented. Finally, an intercooled core and conventional core turbofan engine optimisation procedure using TERA2020 is presented. A back-to-back comparison between the two engine con gurations is performed and fuel optimal designs for 2020 are proposed. Whilst the detailed publications and the work carried out by the author, in a collaborative e ort with other project partners, is presented in the main body of this thesis, it is important to note that this work is supported by 20 conference and journal papers.Item Open Access Parametric analysis of the drag produced by a VHBR engine using CFD(Cranfield University, 2009-10) Gomez-Parada, Josue; Ogaji, S.; Singh, R.The future of the civil aeronautics industry will be determined by the decreasing oil supplies around the world and by more environmentally friendly aircraft designs. Future Gas Turbine engines are being designed focusing on the fuel economy reducing emissions and noise. This project is on the application of Computational Fluid Dynamics (CFD) techniques to the computation and parametric analysis of drag produced by the nacelle of Very High By-pass Ratio (VHBR) engines as integrated into the airframe. Engines based on VHBR concept are consistent with the objectives of VITAL which is an EU project for creating environmentally friendly engine without SFC penalties or impairing other benefits. Three main architectures for the fan were considered for the task, a geared turbofan, contra rotating turbofan and direct drive turbofan. The long range geared turbofan is the one considered in this project. Increasing the BPR for turbofan engines is one of the best options for decreasing the SFC and noise produced by the power plant, unfortunately there are some issues to be considered. One of the major drawbacks when the BPR reaches very high values (VHBR) is the integration to the airframe because of the very large size of the fan. The drag produced by the nacelle has to be countered with propulsive force and therefore decreasing the propulsive efficiency and increasing the SFC. CFD can be used for parametric analysis of drag produced by turbofan nacelles. The analysis was carried out in 3 basic stages. 2D geometry analyses of the afterbody and forebody are the first stage. Small changes to the basic geometry parameters were made in order to form conclusions about which parameters are more significant for drag generation in each section of the nacelle. In the second stage of the project a 3D geometric analysis was carried out with the whole nacelle. The important parameters from the 2D simulations and some of the parameters required for 3D geometry were varied in the analysis. Conclusions were made about the influence of each of the parameters in drag generation and their influence on the interaction between forebody and afterbody. In the third stage of the project, the influence on drag of the positioning of the engine relative to the wing is analyzed. No geometry changes were made and no pylon was used. Conclusions were made from the changes of pressure distribution and supersonic zones and their impact on the drag.Item Open Access Techno-economic and environmental risk assessment of innovative propulsion systems for short-range civil aircraft(Cranfield University, 2009-04) Colmenares Quintero, Ramon Fernando; Ogaji, S.; Singh, R.Aircraft are thought to contribute about 3.5% (IPCC, 1999) to the total radiative forcing (a measure of change in climate) of all the human activities and this figure is forecaste to increase. Future concerns for aviation’s role in climate change are mainly due to the envisaged continued growth in this sector. Growth rates for emissions are less than those for traffic growth since fuel efficiency continues to improve over the years. Despite regular improvements in fuel efficiency, emissions will carry on increasing and several solutions need to be found. The growth of air travel as well and its effect on world economics is hampered by local opposition to aircraft noise. Besides, restrictions on night take-off and landing because of aircraft noise levels leads to a negative impact on the revenues of Europe’s airlines and often results in non-European over-night airport refuelling stops. According to ACARE (Strategic Research Agenda, 2005), the sustainable development of air transport depends on achieving a significant across-the-board reduction in environmental impact, in terms of greenhouse gases, local pollution and noise around airports. Over the past 40 years the introduction of new technology has mitigated the environmental impact of aviation growth, but at the expense of increasing operating costs. Consequently, in order to make aviation more sustainable environmentally and economically, radically innovative turbofans need to be considered and optimised at the aircraft level. Based on the above, this PhD project addresses the following research questions: • The potential of different novel propulsion systems with enhanced propulsive efficiency (using advanced, contra-rotating and geared turbofans) and thermal efficiency (using intercooled and recuperated, and constant volume combustion turbofans) to meet future environmental and economical goals. • The trade-offs to be made between noise, emissions, operating cost, fuel burn and performance using single- and multi-objective optimisation case study. In order to achieve this, a multidisciplinary design framework was developed which is made up of: aircraft and engine performance, weight, cost, noise, emissions, environment, and economics and risk models. An appropriate commercially available optimiser is coupled with this framework in order to generate a powerful aero-engine preliminary design tool. The innovative turbofans were benchmarked against the baseline turbofan at the aircraft level using the A320. The multi-objective trade case study for minimum fuel burn, NOx emissions, engine direct operating cost (DOC) and noise proves that these engines are feasible to meet future noise and emissions requirements for an acceptable cost of ownership. The key driver to lower engine DOC is a considerable fall in fuel consumption. Nevertheless, acquisition and maintenance cost rise owing to hardware complexity. Consequently, further study of these engines is recommended as their environmental performance potential is considerable.Item Open Access TERA for Rotating Equipment Selection(Cranfield University, 2012-01) Khan, Raja S. R.; Pilidis, Pericles; Ogaji, S.; Bennett, Ian; Nicholls, J. R.This thesis looks at creating a multidisciplinary simulation tool for rotating plant equipment selection, specifically gas turbines, for the liquefaction of natural gas (LNG). This is a collaborative project between Shell Global Solutions and Cranfield University in the UK. The TERA LNG tool uses a Techno-economic, Environmental and Risk Analysis (TERA) approach in order to satisfy the multidisciplinary nature of the investigation. The benefits of the tool are to act as an aid to selection, operations and maintenance planning and it also acts as a sensitivity tool for assessing the impact of changes in performance, environmental and financial parameters to the overall economic impact of technology selection. The aim is to not only select technology on the basis of techno-economics but also on the basis of risk analysis. The LNG TERA tool is composed of a number of modules starting with the performance simulation which calculates the thermodynamic conditions in the core of the engine. Next, life estimates of the hot gas path components are made using a mixture of parametric and probabilistic lifing models for the turbine first stage blades, coatings, and combustor liner. This allows for a risk analysis to be conducted before maintenance and economics issues are dealt with. In parallel, emissions estimations are made based on empirical correlations. The modelling exemplifies a methodology which is uniquely applied to this application and there are no studies previous to this which look at so many aspects before making conclusions on plant machinery selection. Comparisons have been done between industrial frame engines based on the General Electric Frame 9E (130 MW) and Frame 7EA (87 MW) engines as well as more complex cycles involving aero-derivation and inter-cooling such as the LM 6000 (42 MW) and LMS 100 (100 MW). Work has also been carried out to integrate the tool to Shell based systems in order to utilise the database of information on failure and maintenance of machinery as well as its performance. The results of the integrated TERA show a clear favour for the aero-derivative engines and the main benefit is the fuel saving, though the life of the hot gas path components is deteriorated much faster. The risk results show that the industrial frame engines have a wider variation in expected life compared to aero-derivatives, though the industrial frames have longer component lives. In the context of maintenance and economics, the aero-derivative engines are better suited to LNG applications. The modular change out design of the aero- derivatives also meant that time to repair was lower, thus reducing lost production. Application of the LNG TERA tool was extended to power generation whereby a series of 6 engines were simulated. The changes required to the modelling were minimal and it shows the flexibility of the TERA philosophy. This study was carried out assuming a given ratio of load split between the engines and hence is sensitive to the way an operator demands power of the engine as opposed to LNG application where the operator tries to drive the engine as hard as possible to get the most production out of the train. The study was limited in the modes of failure which were investigated, a major further work would be to extend the methodology to more components and incorporate fatigue failure. Further, the blade creep and probabilistic coating models were very sensitive to changes in their respective control parameters such as coating thickness allowances and firing temperature. The contribution to the project from the MBA is the statistical techniques used to conduct the risk analysis and data handling as well as financial management techniques such as the Net Present Value (NPV) methodology for project evaluations.