The Advisory Council of Aeronautical Research in Europe (ACARE) has set record emission reduction targets for 2020, in response to increased awareness of global warming issues and the forecast high level of growth in global air traffic. In order to meet this legislation engine designers have to consider new and unconventional designs. An intercooled aero-engine with a heat exchanger (HX) positioned between the IP and HP compressors has the potential to reduce emissions and/or reduce specific fuel consumption relative to conventional engine cycles. In such an engine a coolant delivery system is required to bleed a proportion of the bypass flow, from behind the fan outlet guide vane (FOGV), rapidly diffuse the flow (to reduce pressure loss through the HX modules) and present it to the intercooler (i.e. heat exchanger) modules for cooling. This spent cooling air is then fed back into the bypass duct. To realise the benefits of the intercooled cycle the coolant delivery system must diffuse the flow, within the geometrical constraints, with minimal pressure loss and present it to the heat exchanger modules with suitable flow characteristics over a range of operating conditions. Therefore, a predominately experimental study, complemented with CFD predictions, was undertaken to investigate the design and performance of a coolant delivery system aimed at providing high pressure recovery in a relatively short length. For this to be achieved some pre-diffusion of the flow is required upstream of the offtake (i.e. by making the offtake larger than the captured streamtube), with a controlled diffuser or hybrid diffuser arrangement located downstream of the offtake. Although targeted at an intercooled aero-engine the concept of a system that produces a high pressure recovery in a limited length is applicable to a variety of applications. Experimental data were obtained on a modified existing low speed isothermal annular test facility operating at nominally atmospheric conditions. The offtake must operate aft of the FOGV in a highly complex flow field environment. Hence, a 1½ stage axial flow compressor (IGV, rotor and modified OGV) was used to simulate the unsteady blade wakes, secondary flows, loss cores and other turbo-machinery features that can significantly influence offtake performance. Preliminary numerical (CFD) studies enabled an offtake configuration to be determined and provided understanding of the governing fluid mechanic processes. A relatively small scale, low speed test facility was designed that had the capability to evaluate aerodynamic processes in isolation (i.e. pre-diffusion, controlled diffusion, hybrid diffusion) and full system modelling to enable the complex interaction between these flow processes to be assessed. Hence an optimal system could be characterised in terms of total pressure loss, static pressure recovery and flow profiles at HX inlet. Measurements and numerical predictions are initially presented for a baseline configuration with no offtake present. This enabled the OGV near field region to be characterised and provided a datum, relative to which the effects of introducing an offtake could be assessed. The results showed that in the near field region (i.e. within one chord downstream of the FOGV) the high velocity gradients in the circumferential direction, and associated turbulent shear stresses, dominate the profile mixing and loss production. There is little mixing out of profiles in the radial direction. Furthermore, the relatively large amount of kinetic energy associated with the compressor efflux and its subsequent mixing to a more uniform profile (i.e. reduced blockage) results in a significant static pressure recovery (Cp=5.5%). With the offtake present a variety of configurations were investigated including different levels of pre-diffusion, prior to the offtake, and different offtake positions. This enabled evaluation of the upstream pressure effects and interaction with the upstream FOGV. For very compact systems of short length, such that the gap between the OGV and offtake is relatively small, the amount of pre-diffusion achievable is limited by the offtake pressure field and its impact on the upstream OGV row. This pressure field is also influenced by parameters such as the non-dimensional offtake height and splitter thickness. For systems of increased length a significant amount of flow pre-diffusion can be achieved with little performance penalty (relative to the datum configuration). Hence, the loss associated with mixing blade wakes and secondary flows in an adverse pressure gradient is relatively small. However, the pre-diffusion level is eventually limited, to approximately 1.5, by the increased distortion and pressure losses associated with the captured streamtube. Further measurements were made with various controlled diffuser and hybrid diffusers (of varying area ratio) downstream of the offtake and various levels of pre-diffusion. The flow profile that is presented to the controlled diffuser is directly influenced by the upstream pre-diffusion process. Hence, in this case the upstream-downstream interaction is relatively strong. Conversely, the downstream-upstream interaction, between the controlled diffuser and pre-diffusion process, is relatively weak and thus has little effect on the upstream flow field. The data enabled an optimal system to be characterised (pre-diffusion/controlled diffusion split) in terms of total pressure loss, static pressure recovery and flow profiles at HX inlet. A total system diffusion of 1.8 was achievable with a pre-diffusion of 1.4 and controlled diffusion of 1.25, with further increases in either the pre-diffusion level or the controlled diffuser area ratio destabilising the system. This was achieved with an absolute mass weighted total pressure loss of 11% measured from FOGV inlet to the controlled diffuser exit plane. Utilising a hybrid bled diffuser, combined with the pre-diffusion, enabled a total system diffusion of 2.24 to be achieved. The system incorporated a 6% bleed from the hybrid diffuser and a system total pressure loss of 13%. Experimental and computational results obtained in the current research have provided an understanding of the governing flow mechanisms and quantified the geometric and aerodynamic interaction of the offtake with the FOGV and between the diffusion processes. This has enabled a design methodology to be outlined that provides approximate information on system geometry and performance (in terms of optimal diffusion split and total pressure loss) for future coolant delivery systems with minimal effort. Preliminary design maps have been developed to define the magnitude of the interaction between the offtake and FOGV in terms of the offtake height, pre-diffusion level, the splitter thickness and the axial distance between the fan OGV and offtake. In this way systems of optimal diffusion split, minimum pressure loss and minimal axial length can be determined.

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Master thesis is concerned with gas turbines from Siemens company. The thesis consists of two main parts. In the first part describes the different types of turbines, their characteristics and use in practice. The following is a detailed description of components and systems the biggest industrial gas turbine SGT-800. The second part discusses about the necessary steps for commissioning turbine. These particulars are managing software, testing, commissioning and phasing of the turbine generator to the distribution network. The conclusion is devoted to the example of calculating return investment on the overall gas turbine project.

The main goal of my thesis is to carry out thermic calculations for adjusted conditions of electric and heat energy consumption. The power of the generator is 330 MW. In the proposal, you can find combustion trubines type GE 9171E. Steam-gas power plant is designed to combust metallurgical gases. Effort of the thesis focuses also on giving a new informations about trends in combinated production of electric and heat energy.

[pt] Turbinas a gás industriais modernas instaladas em usinas termelétricas têm seus parâmetros de desempenho monitorados em tempo real. Contudo, existem inúmeras falhas de operação que são impossíveis de serem detectadas pela simples visualização destes parâmetros, uma vez que a condição de operação do equipamento é influenciada por diversos fatores. Sistemas de diagnóstico são usualmente oferecidos pelos fabricantes destes equipamentos, mas não são divulgados na literatura aberta, que conta em geral com trabalhos aplicados a casos específicos e a turbinas aeronáuticas. Esta dissertação propõe um sistema de diagnóstico de falhas em turbinas a gás, o qual opera através da contínua comparação entre sinais medidos em campo, os quais são simulados por um programa computacional, e resultados gerados por um modelo de referência, simulador da turbina saudável. O sinal comparado serve de entrada para um sistema fuzzy, que identifica e quantifica a severidade das falhas. Foram testadas falhas fictícias no compressor e foi avaliada a influência da mudança de geometria na calibração do sistema. Os resultados mostraram a robustez do sistema e sua capacidade de aplicação em uma situação real. / [en] Modern industrial gas turbines installed in thermal power plants have its performance parameters monitored in real time, however, there are innumerable operation faults that cannot be detected by a simple visual analysis of these parameters, once the equipment operating condition is influenced by several factors. Diagnosis systems are usually offered by the manufacturers of these equipments, but the methodologies are not published in the open literature, which is mostly dedicated to aircraft engines. This dissertation proposes a gas turbine diagnosis system that operates through the continuous comparison between the field measured signals, simulated by a software, and results generated by a reference numerical model, which represents the healthy gas turbine. The compared signal is used as input to a fuzzy system that identifies and quantifies the faults severity. Dummy compressor faults have been tested and the influence of the variable geometry has been analyzed during the system calibration. The results have shown the robustness of the system and its capability to be applied in a real world situation.

[pt] A deterioração do desempenho da turbina a gás é resultado de vários tipos de falhas, como acúmulo de sujeira, erosão e corrosão, que afetam os componentes no caminho do gás, sendo os principais o compressor, o combustor e a turbina. No presente trabalho é avaliado o desempenho de Redes Neurais Artificiais (RNA) no emprego de diagnóstico de falha de turbinas a gás. Todas as redes projetadas são do tipo MLP (multi-layer perceptron) com algoritmo de retropropagação (backpropagation). Para cada função de diagnóstico, várias arquiteturas foram testadas, modificando parâmetros de rede como o número de camadas escondidas e o número de neurônios em cada uma destas camadas. As RNAs para diagnóstico de falhas foram aplicadas ao modelo termodinâmico de uma turbina a gás industrial. Este modelo foi responsável pela criação de dados da usina saudável e também degradada, utilizados para o treinamento e validação das redes. Com os resultados obtidos do treinamento das redes é possível mostrar que as mesmas são capazes de detectar, isolar e quantificar falhas de componentes de turbinas a gás de forma satisfatória. / [en] The gas turbine performance deterioration is a result of several types of faults such as fouling, erosion and corrosion, which affects the components throughout the gas path. As the most significant of these components we can enumerate the compressor, the combustion chamber and the turbine itself. In this work the performance of different types of Artificial Neural Networks (ANN) are evaluated in the diagnosis of this kind of fault. Every neural network designed in this work is MLP (multi-layer perceptron) with back propagation algorithm. For each diagnosis function several architectures were tested, varying network parameters as the numbers of hidden layers and the number of neurons in each layer. The ANNs for fault diagnosis were applied in an industrial gas turbine thermodynamic model. This model was also used for healthy and degraded turbine data generation, which were used for ANNs training and validation. With the ANNs training results we can conclude that these networks are capable of detecting, isolating and quantifying gas turbine components faults in a satisfactory way.

Superalloys are widely applied as materials for components in the hot section of gas turbines. As superalloys have a limited oxidation life, the application of a coating is vital. The most commonly applied coatings in stationary gas turbines are MCrAlY coatings. Since the turbine components are exposed to high cyclic thermal stresses, MCrAlY coatings must also show a high thermal fatigue resistance. In this thesis, the effect of Cobalt and Rhenium on microstructure, oxidation and thermal fatigue of NiCoCrAlY coatings is presented. Additionally the condition of the coatings after testing in an industrial gas turbine is shown. The influence of Cobalt and Rhenium on coating microstructure was investigated by thermodynamic modelling and by metallography. It could be shown that both elements reduce the γ`-phase fraction and increase the β-phase fraction owing to an expansion of the γ+β field in the phase diagram. Modelling showed that Rhenium promotes the formation of α-Cr, which could be explained by a shift of the α-Cr solvus to higher temperatures and lower Cr concentrations. In the real coatings Re causes the precipitation of TCP-phase. The oxide scale growth rate is increased by Cobalt and Rhenium and it appears that Yttrium plays a significant role for that effect. Coating consumption due to simultaneous oxidation and interdiffusion could be decreased by the application of Cobalt and Rhenium. In thermal fatigue testing Rhenium reduces the time to crack initiation and increases crack propagation rate, although it could be shown that Rhenium increases the creep resistance of the coating. The effect could be explained by the influence of Rhenium on the microstructure, which increases creep resistance, but also reduces the ductility of the coating.

This work represents the integration of a hybrid system based on Micro Gas Turbine system available at the division of Heat and Power Technology at KTH and Solid Oxide Fuel Cell.  The MGT available is an externally fired recuperated and the SOFC is of planar type. Before the integration, these two different candidates of environmentally friendly power generation systems are discussed separately. The advantages and performances of the two separate systems are presented. The operation conditions as pressure and temperature are fixed at different stations based on the previous experiments. Keeping the parameters constant a reduction of fuel to the combustor could be achieved. Finally, layout of the hybrid system diagram is suggested and orientation of a computer designed layout is also presented. An efficiency of 65% from SOFC has been achieved and reductions of the fuel by more than 50% to the MGT are noteworthy.

Although pre-swirlers play a determinant role in the transport of air from stationary parts to rotating holes, knowledge about their actual performance is limited. Therefore, this paper aims to relate how the pre-swirler pressure drop affects the performance of different pre-swirlers in terms of discharge coefficient, adiabatic pre-swirl effectiveness, and swirl ratio. The results are extracted from numerical simulations carried out on three different designs, two guide vanes, and a nozzle. When available, the results are compared to experimental data. The guide vanes have shown similar responses to the pressure drop variations. Their discharge coefficients remain relatively insensitive with an average value of 97%. The swirl ratio range from 0.704 to 1.013 and 0.703 to 1.023 respectively for a pressure drop varying from 3 to 7 bars. The adiabatic pre-swirl effectiveness is of 96% and 94%, respectively, under steady state operation.The nozzle design has shown inferior performance as compared to the guide vane designs. Its discharge coefficient remains around 91% and the swirl ratio varies between 0.678 and 1.121 for a pressure drop ranging from 3 to 10 bars. Under steady state operation, the adiabatic pre-swirl effectiveness is 1.22. The influence of through-flows on the aforementioned parameters was also analyzed. It was observed that the through-flow deteriorates the performance of the pre-swirlers, whether in terms of dimensionless pre-swirl effectiveness, or swirl ratio. The discharge coefficient was however not affected.

Biomass is one of the main natural resources in Sweden.Increased utilisation of biomass for energy purposes incombined heat and power (CHP) plants can help the country meetits nuclear phase-out commitment. The present low-CO2 emissioncharacteristics of the Swedish electricity production system(governed by hydropower and nuclear power) can be retained onlyby expansion of biofuels in the CHP sector. Domestic Swedishbiomass resources are vast and renewable, but not infinite.They should be utilised as efficiently as possible in order tomeet the conditions for sustainability in the future.Application of efficient power generation cycles at low cost isessential for meeting this challenge. This applies also tomunicipal solid waste (MSW) incineration with energyextraction, which is to be preferred to landfilling. Modern gas turbines and internal combustion engines firedwith natural gas have comparatively low installation costs,good efficiency characteristics and show reliable performancein power applications. Environmental and source-of-supplyfactors place natural gas at a disadvantage as compared tobiofuels. However, from a rational perspective, the use ofnatural gas (being the least polluting fossil fuel) togetherwith biofuels contributes to a diverse and more secure resourcemix. The question then arises if both these fuels can beutilised more efficiently if they are employed at the samelocation, in one combined cycle unit. The work presented herein concentrates on the hybriddual-fuel combined cycle concept in cold-condensing and CHPmode, with a biofuel-fired bottoming steam cycle and naturalgas fired topping gas turbine or engine. Higher electricalefficiency attributable to both fuels is sought, while keepingthe impact on environment at a low level and incorporating onlyproven technology with standard components. The study attemptsto perform a generalized and systematic evaluation of thethermodynamic advantages of various hybrid configurations withthe help of computer simulations, comparing the efficiencyresults to clearly defined reference values. Results show that the electrical efficiency of hybridconfigurations rises with up to 3-5 %-points in cold-condensingmode (up to 3 %-points in CHP mode), compared to the sum of twosingle-fuel reference units at the relevant scales, dependingon type of arrangement and type of bottoming fuel. Electricalefficiency of utilisation of the bottoming fuel (biomass orMSW) within the overall hybrid configuration can increase withup to 8-10 %-points, if all benefits from the thermalintegration are assigned to the bottoming cycle and effects ofscale on the reference electrical efficiency are accounted for.All fully-fired (windbox) configurations show advantages of upto 4 %-points in total efficiency in CHP mode with districtheating output, when flue gas condensation is applied. Theadvantages of parallel-powered configurations in terms of totalefficiency in CHP mode are only marginal. Emissions offossil-based CO2 can be reduced with 20 to 40 kg CO2/MWhel incold-condensing mode and with 5-8 kg CO2 per MWh total outputin CHP mode at the optimum performance points. Keywords: Biomass, Municipal Solid Waste (MSW), Natural Gas,Simulation, Hybrid, Combined Cycle, Gas Turbine, InternalCombustion Engine, Utilization, Electrical Efficiency, TotalEfficiency, CHP. / NR 20140805