Future Aero Engine Designs: An Evolving Vision

Gas turbine engines will still represent a key technology in the next 20-year energy scenarios, either in stand-alone applications or in combination with other power generation equipment. This book intends in fact to provide an updated picture as well as a perspective vision of some of the major improvements that characterize the gas turbine technology in different applications, from marine and aircraft propulsion to industrial and stationary power generation. Therefore, the target audience for it involves design, analyst, materials and maintenance engineers. Also manufacturers, researchers and scientists will benefit from the timely and accurate information provided in this volume. The book is organized into five main sections including 21 chapters overall: (I) Aero and Marine Gas Turbines, (II) Gas Turbine Systems, (III) Heat Transfer, (IV) Combustion and (V) Materials and Fabrication

Assessment of the performance potential for a two-pass cross flow intercooler for aero engine applications

Intercoolers have recently received a considerable attention as a means to improve aero engine efficiency. Intercoolers have the potential to improve engine SFC, ease the design of an efficient turbine cooling system by reducing compressor exit temperatures and hence cooling air temperatures, as well as reducing NOx emissions. Intercooling may also provide benefits by increasing the specific output of the engine core and therefore reduce total engine weight. The performance potential for a two-pass cross flow intercooler has been estimated through an analysis of a long range mission for a geared turbofan engine. The application of a set of CFD based correlations allows the simultaneous coupled optimization of the intercooler conceptual design parameters and the engine design. The coolant air for the intercooler is ejected through a separate variable exhaust nozzle which is used to optimize the engine performance in cruise. By comparing the optimized intercooled geared engine with an optimized advanced non-intercooled geared engine, a reduction of 4.8% fuel burn is observed

On gas turbine conceptual design.

The thesis begins with a review of the evolution of the industry's vision for the aero-engine design of the future. Appropriate research questions are set that can influence how this vision may further evolve in the years to come. Design constraints, material technology, customer requirements, noise and emissions legislation, technology risk and economic considerations and their effect on optimal concept selection are discussed in detail. Different aspects of the pedagogy of gas turbine conceptual design as well as information on the Swedish and Brazilian educational systems are also presented. A multi-disciplinary aero-engine conceptual design tool is utilised for assessing engine/aircraft environmental performance. The tool considers a variety of disciplines that span conceptual design including: engine performance, engine aero-dynamic and mechanical design, aircraft design and performance, emissions prediction and environmental impact, engine and airframe noise, and production, maintenance and direct operating costs. With respect to addressing the research questions set, several novel engine cycles and technologies - currently under research - are identified. It is shown that there is great potential to reduce fuel consumption for the different concepts identified, and consequently decrease the CO₂ emissions. Furthermore, this can be achieved with sufficient margin from the NOᵪ certification limits set by International Civil Aviation Organisation, and in line with the medium-term and long-term goals set through it's Committee on Aviation Environmental Protection. The option of an intercooled-core geared-fan aero-engine for long-haul applications is assessed by means of a detailed design space exploration. An attempt is made to identify the fuel burn optimal values for a set of engine design parameters by varying them all simultaneously, as well as in isolation. Different fuel optimal designs are developed based on different sets of assumptions. Evidence is provided that higher overall pressure ratio intercooled engine cycles become more attractive in aircraft applications that require larger engine sizes. The trade-off between the ever-increasing energy efficiency of modern aero-engines and their NOᵪ performance is assessed. Improving engine thermal efficiency has a detrimental effect on NOᵪemissions for traditional combustors, both at high altitude and particularly at sea-level conditions. Lean-combustion technology does not demonstrate such behaviour and can therefore help decouple NOᵪ emissions performance from engine thermal efficiency. If we are to reduce the contribution of aviation to global warming, however, future certification legislation may need to become more stringent and comprehensive, i.e., cover high altitude conditions. By doing so we can help unlock the competitive advantage of lean burn technology in relation to cruise NOᵪ and mission performance. Finally, some insight is provided on the potential benefits to be tapped from a transition from the traditional deterministic approach for system analysis to a stochastic (robust design) approach for economic decision-making under uncertainty. A basic methodology is outlined and applied on a specific conceptual design case for a conventional turbofan engine. The sensitivity of an optimal engine design obtained deterministically to real-life uncertainties is found to be far from negligible. The considerable impact of production scatter, measurement uncertainties as well as component performance deterioration, on engine performance must be catered for; this includes taking into consideration control system design aspects. A fast analytical approach is shown to be sufficiently accurate for the conceptual design process, particularly for estimating key performance parameters. These relate to type-test certification and performance retention guarantees including preliminary estimates of engine production margins. Lessons learned are presented from: (i) the integration of different elements of conceptual design in a new BSc course and an existing traditional MSc course on gas turbine technology, (ii) the development of an intensive course on gas turbine multi-disciplinary conceptual design. The results from the use of problem-based learning are very encouraging, in terms of enhancing student learning and developing engineering skills.PhD in Aerospac

Discrimination of Rapid and Gradual Deterioration for an Enhanced Gas Turbine Life-cycle Monitoring and Diagnostics

Advanced engine health monitoring and diagnostic systems greatly benefit users helping them avoid potentially expensive and time-consuming repairs by proactively identifying shifts in engine performance trends and proposing optimal maintenance decisions. Engine health deterioration can manifest itself in terms of rapid and gradual performance deviations. The former is due to a fault event that results in a short-term performance shift and is usually concentrated in a single component. Whereas the latter implies a gradual performance loss that develops slowly and simultaneously in all engine components over their lifetime due to wear and tear. An effective engine life-cycle monitoring and diagnostic system is therefore required to be capable of discriminating these two deterioration mechanisms followed by isolating and identifying the rapid fault accurately. In the proposed solution, this diagnostic problem is addressed through a combination of adaptive gas path analysis and artificial neural networks. The gas path analysis is applied to predict performance trends in the form of isentropic efficiency and flow capacity residuals that provide preliminary information about the deterioration type. Sets of neural network modules are trained to filter out noise in the measurements, discriminate rapid and gradual faults, and identify the nature of the root cause, in an integrated manner with the gas path analysis. The performance of the proposed integrated method has been demonstrated and validated based on performance data obtained from a three-shaft turbofan engine. The improvement achieved by the combined approach over the gas path analysis technique alone would strengthen the relevance and long-term impact of our proposed method in the gas turbine industry

Assessment of an energy-efficient aircraft concept from a techno-economic perspective

An increase in environmental awareness in both the aviation industry and the wider global setting has led to large bodies of research dedicated to developing more sustainable technology with a lower environmental impact and lower energy usage. The goal of reducing environmental impact has necessitated research into revolutionary new technologies that have the potential to be significantly more energy efficient than their predecessors. However, for innovative technologies in any industry, there is a risk that adoption will be prohibitively expensive for commercial application. It is therefore important to model the economic factors of the new technology or policy at an early stage of development. This research demonstrates the application of a Techno-economic Environmental Risk Assessment framework that may be used to identify the economic impact of an energy-efficient aircraft concept and the impact that environmental policy would have on the viability of the concept. The framework has been applied to a case study aircraft designed to achieve an energy saving of 60% in comparison to a baseline 2005 entry-into-service aircraft. The model compares the green aircraft concept to a baseline conventional aircraft using a sensitivity analysis of the aircraft direct operating cost to changes in acquisition and maintenance cost. The research illustrates an economically viable region for the technology. Cost margins are identified where the increase in operating cost due to expensive novel technology is counterbalanced by the reduction in cost resulting from low energy consumption. Viability was found to be closely linked to fuel price, with a low fuel price limiting the viability of energy-efficient aviation technology. In contrast, a change in environmental taxation policy was found to be beneficial, with the introduction of carbon taxation incentivising the use of an environmentally optimised aircraft

Chapter A Framework for Learning System for Complex Industrial Processes

Due to the intense price-based global competition, rising operating cost, rapidly changing economic conditions and stringent environmental regulations, modern process and energy industries are confronting unprecedented challenges to maintain profitability. Therefore, improving the product quality and process efficiency while reducing the production cost and plant downtime are matters of utmost importance. These objectives are somewhat counteracting, and to satisfy them, optimal operation and control of the plant components are essential. Use of optimization not only improves the control and monitoring of assets, but also offers better coordination among different assets. Thus, it can lead to extensive savings in the energy and resource consumption, and consequently offer reduction in operational costs, by offering better control, diagnostics and decision support. This is one of the main driving forces behind developing new methods, tools and frameworks. In this chapter, a generic learning system architecture is presented that can be retrofitted to existing automation platforms of different industrial plants. The architecture offers flexibility and modularity, so that relevant functionalities can be selected for a specific plant on an as-needed basis. Various functionalities such as soft-sensors, outputs prediction, model adaptation, control optimization, anomaly detection, diagnostics and decision supports are discussed in detail

A Framework for Learning System for Complex Industrial Processes

Due to the intense price-based global competition, rising operating cost, rapidly changing economic conditions and stringent environmental regulations, modern process and energy industries are confronting unprecedented challenges to maintain profitability. Therefore, improving the product quality and process efficiency while reducing the production cost and plant downtime are matters of utmost importance. These objectives are somewhat counteracting, and to satisfy them, optimal operation and control of the plant components are essential. Use of optimization not only improves the control and monitoring of assets, but also offers better coordination among different assets. Thus, it can lead to extensive savings in the energy and resource consumption, and consequently offer reduction in operational costs, by offering better control, diagnostics and decision support. This is one of the main driving forces behind developing new methods, tools and frameworks. In this chapter, a generic learning system architecture is presented that can be retrofitted to existing automation platforms of different industrial plants. The architecture offers flexibility and modularity, so that relevant functionalities can be selected for a specific plant on an as-needed basis. Various functionalities such as soft-sensors, outputs prediction, model adaptation, control optimization, anomaly detection, diagnostics and decision supports are discussed in detail

Multi-disciplinary conceptual design of future jet engine systems

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