Wind energy has emerged as a promising and renewable solution to reduce reliance on fossil fuels in remote off-grid locations. Conventional wind turbine towers are made from concrete or steel, which present several significant drawbacks in certain applications. The use of lightweight and corrosion-resistant fibre reinforced polymer (FRP) tubes as permanent structural formwork can mitigate these challenges. Existing literature has highlighted the performance of concrete-filled FRP tubes (CFFTs) through experiments and successful applications in the field. However, only a few cantilever CFFTs have been tested, and their sizes were much smaller than required for wind turbine towers. In consequence, this thesis focuses on relatively large cantilever CFFTs at a scale representative of small wind turbine towers. The finite element (FE) method was adopted to simulate the behaviour of CFFT towers using the commercial software ABAQUS. The first part of this thesis presents the development and validation of CFFT FE models under bending and axial loading conditions, as well as hollow FRP tubes under bending. The models were compared to experimental results reported by Fam (2000) to ensure the selection of appropriate material properties. Good agreements were observed, and the accuracy of the FE modelling approach was proved. Subsequently, a parametric study was conducted to explore the feasibility of CFFTs for wind turbine towers. The analyses of cantilever towers with different geometric properties and reinforcement configurations under concentrated lateral load were performed first. Then, a cantilever CFFT tower under different loading configurations was tested. It is noted that towers subjected to concentrated load had the lowest load capacity and stiffness. Conclusions were made that with or without axial load, lateral load eccentricity does not affect the behaviour of cantilever CFFTs significantly. Meanwhile, the increase in height-to-diameter ratio decreases the load capacity and stiffness of cantilever CFFTs. Finally, the CFFT tower results were compared with concrete and steel tubular models with similar geometry. The results suggest that CFFTs have better overall performance than the other two types of towers. They are also superior with respect to flexibility in installation and their durability.

Diploma thesis focus on the design of turbocharger in SW MS Excel. For required flow and pressure ratio, the thermodynamics parameters were calculated for the turbocharger. From these, geometry was designed and the condition of mediums was calculated for each part of the turbine and compressor. At last basic characteristics of the turbine and compressor on varying the regime of engine operation the rotation was made and offered an idea about the working point position.

The master´s thesis concentrates on a project of condensing steam turbine for existing heating plant with back pressure turbine. The master´s thesis subject consists in the thermodynamic calculation of regulating stage and turbine stages. Design documentation is worked up according to the calculated record. From calculated power of turbine is worked a basic project of gearbox and disposal arrangement system.

The legislations on greenhouse gas emissions are getting tougher and tougher every year. This drives the demand for energy efficient gas turbines with as low emissions as possible. This poses the challenge to manufacturers of constructing gas turbines with lessened environmental impact, but with maintained performance. To obtain this, there is a need of optimization of current principles along with completely new ideas and solutions. One part of developing new, improved gas turbine configurations is to create prototypes and test them. However, creating and testing a gas turbine is a both expensive and time consuming. They are large in every sense of the word: they are long, heavy, demand lots of fuel, create massive air flows and generate a lot of energy. Designing, building and testing new turbine configurations are therefore risky, as it requires investing lots of time and money. This means that it is highly profitable to have accurate, dependable simulation models. This thesis uses Matlab Simulink to create a dynamic model of a single axis gas turbine with nine stage compressor and a single stage turbine. The modeling of the compressor composes a large part of the work in the thesis, where the Ellipse compressor model is introduced and implemented on a gas turbine compressor. The Ellipse model creates a parametric model of each of the nine compressor stages by the use of elliptic equations. The goal is to provide an alternative to the look-up table model of compressors, which are common to find in modeling papers today. In the design of the compressor, a single stage map is scaled nine different ways to mimic the design of a real life nine stage compressor. The stage scaling principle is based on a linear model that correlates stage size with maximum available pressure ratio at optimal speed. The constructed compressor model is put in a simulated test bench and a compressor map is created. The map is found to in most aspects resemble a general compressor map. Furthermore, the thesis contains a run-through of the sub-models of the rest of the turbine, namely combustion chamber and fuel injection, compressor turbine and torque dynamics. For each sub-model, the most important equations and inspirations for these are presented. Finally, a description of the simulation scenarios and the simulation software, Matlab Simulink, is provided. The model is tested in steady-sate operation around its optimal operating point, as well as during a transient in a benign operating zone, in terms of efficiency. The results of these simulations are analyzed and a flaw in the control strategy is pinpointed. An alternate control strategy is proposed, described and implemented. A comparison is made between the original and alternative control strategies, and it is concluded that the new controller manages to mitigate the problems identified in the original simulations. / I takt med att lagstiftningen skärps mer och mer på utsläppsområdet ställs större krav på gasturbiners miljöpåverkan. Tillverkare vill som följd av detta minimera utsläppen, men ändå bibehålla prestanda. För att uppnå detta krävs optimeringar av befintliga principer och i vissa fall helt nya tankar, lösningar och idéer. Ett led i att ta fram nya, bättre gasturbiner är att skapa prototyper och testköra dessa. Det är emellertid en kostsam process att konstruera och testköra en gasturbin, vilket gör vinsterna med pålitliga simuleringsmodeller påtagliga både tidsmässigt och ekonomiskt. Detta arbete innefattar huvudsakligen konstruktionen av en dynamisk modell av en gasturbin. Den modellerade gasturbinen har nio kompressorsteg, en roterande axel samt ett turbinsteg. Modelleringen av kompressorn utgör en stor del av arbetet, där Ellipsemodellen introduceras och implementeras på gasturbinskompressorer. Ellipsemodellen parametriserar en inmatad kompressormapp med elliptiska ekvationer och möjliggör ett steg från den sedvanliga modelleringen av kompressorer som lookup-tables som annars är förhärskande i gasrtubinmodellering. Kompressorns nio steg skalas och modelleras individuellt med en inbördes skalningsprincip som bygger på de respektive stegens maximala tryckkvot vid optimal hastighet. Den konstruerade kompressorn sätts i en simulerad testbänk och en kompressormapp skapas, vilken inses i mångt och mycket likna en allmän kompressormapp. En detaljerad genomgång ges av alla gasturbinens submodeller av kompressor, förbränning och bränsleinsprutning samt turbin och rotationsdynamik. De viktigaste ekvationerna som styr respektive modell, samt inspirationskällor till dessa föredras under modelleringskapitlet. Vidare avhandlas simuleringsscenario och den använda programvaran Matlab Simulink beskrivs i korthet. Den totala gasturbinmodellen testas i stationär drift och en längre transient genom dess föredragna arbetsområde. Resultaten därifrån utvärderas och en alternativ regulatorstruktur föreslås och implementeras. Resultaten med den alternativa regulatorstrukturen diskuteras och jämförs med de identifierade bristerna som skulle åtgärdas, och det konstateras att den nya regulatorn lyckas åtgärda de identifierade bristerna i den ursprungliga designen.

<p>Pressure gain combustion is beneficial for engine cycle efficiency, compactness, and less emissions. In this disseration, two classes of fluid expansions systems were developed to harness power from the high-speed flow delivered by the pressure gain combustor: a compact expansion system and an efficiency expansion system. In addition, a new class of pressure probes for expansion systems is developed.</p> <p>A numerical methodology is carried out to design and characterize these expansion devices and measurement systems via steady and unsteady Reynolds Averaged Navier stokes simulations. Firstly, the compact expansion system is achieved by developing a supersonic axial turbine. Performance of the supersonic axial turbine exposed to fluctuations from a nozzle downstream of a rotating detonation combustor is assessed with an increased level of complexity, including time-resolved stator, time-resolved rotor, and time-resolved turbine stage characterization. Power extraction, damping of fluctuations, and loss budgeting are evaluated. Unsteady heat transfer assessment is performed to investigate the convective heat flux distribution and decomposition. A performance map is constructed to explore the operating limit. Afterwards, the efficient expansion system is achieved by retrofitting an existing subsonic axial turbine. Without redesigning turbine airfoils, the stator endwall contour was modified to integrate the subsonic axial turbine to a diffuser and a rotating detonation combustor. Performance of the retrofitted subsonic axial turbine exposed to fluctuations form a diffuser is evaluated at several frequencies, amplitudes and inlet Mach numbers, with an increased level of model fidelity, including unsteady stator alone, unsteady turbine stage with a reduced model, full unsteady turbine stage assessment. Turbine efficiency, damping of oscillations, and loss budgeting are assessed. A multi-step optimization strategy is utilized to enhance turbine efficiency by improving the endwall contouring. A performance map is created to examine the operating range. Finally, a new type of pressure probes was developed and angular calibration was performed. A whisker-inspired design enabled the reduction of the vortex shedding effect.</p>

This thesis is a collaboration between Siemens Industrial Turbomachinery(SIT) and Royal Institute of Technology(KTH). It is aimed to study and compare the outputs of two different computational approaches in axial gas turbine design procedure with the data obtained from experimental work on a test turbine. The main focus during this research is to extend the available test databank and to further understand and investigate the turbine stage efficiency, mass flow parameters and reaction degree under different working conditions. Meanwhile the concept and effect of different loss mechanisms and models will be briefly studied.  The experimental part was performed at Heat and Power  Technology department on a single stage test turbine in its full admission mode. Three different pressure ratios were tested. For the medium pressure ratio a constant temperature anemometry (CTA) method was deployed in two cases, with and without turbulence grid, to determine the effect of free-stream turbulence intensity on the investigated parameters. During the test campaign the raw gathered data was processed with online tools and also they served as boundary condition for the computational codes later.  The computational scope includes a one-dimensional design approach known as mean-line calculation and also a two-dimensional method known as throughflow calculation. An in-house SIT software, CATO, generated the stage geometry (vane, blade and the channel) and then two other internal computational codes, MAC1 and BETA2, were employed for the one-dimensional and two-dimensional computations respectively. It was observed that to obtain more accurate mass flow predictions a certain level of channel blockage should be implemented to represent the boundary layer development and secondary flow which is typically around 2%. The codes are also equipped with two options to predict the friction loss: One is a more empirical correlation named as the Old approach in SIT manuals and the other works based on allocation of boundary layer transition point, named as BL in the present thesis. Simulations were done by use of both approaches and it turned out that the latter works more accurately if it is provided with appropriate transition point and blockage estimation.  The measured data also suggests the idea that the transition point of the vane and blade is not affected by a change in turbulence intensity at least up to 6% in the tested Reynolds numbers, . Amongst different solutions the one which used BL approach and constant transition point (while the turbulence intensity changed) managed to predict this behavior. Also it was investigated and revealed that the codes inherently predict poor results in off-design loadings which is mainly due to positive incidence angle in addition to high spanwise gradient of the flow parameters.

This research has a small portion focused on interior serpentine channels, with the primary focus on improving the effectiveness of the film cooling technique through the use of a new approach to film cooling. This new approach uses a set of three holes sharing the same inlet and diverging from the central hole to form a three-legged, or tripod, design. The tripod design is examined in depth, in terms of geometric variations, through the use of flat plate and cascade rigs, with both transient and steady-state experiments. The flat plate tests provide a simplified setting in which to test the design in comparison to other geometries, and establish a baseline performance in a simple flow field that does not have the complications of surface curvature or mainstream pressure gradients. Cascade tests allow for testing of the design in a more realistic setting with curved surfaces and mainstream pressure gradients, providing important information about the performance of the design on suction and pressure surfaces of airfoils. Additionally, the cascade tests allow for an investigation into the aerodynamic penalties associated with the injection hole designs at various flow rates. Through this procedure the current state of film cooling technology may be improved, with more effective surface coverage achieved with reduced coolant usage, and with reduced performance penalties for the engine as a whole. This research has developed a new film hole design that is manufacturable and durable, and provides a detailed analysis of its performance under a variety of flow conditions. This cooling hole design provides 40% higher cooling effectiveness while using 50% less coolant mass flow. The interior serpentine channel research provides comparisons between correlations and experiments for internal passages with realistic cross sections. / Ph. D.

This licentiate thesis deals mainly with modelling ofturbocharged SIengines. A model of a 4-cylinder engine was runin both steady state and transient conditions and the resultswere compared to measured data. Large differences betweenmeasurements and simulations were detected and the reasons forthis discrepancy were investigated. The investigation showedthat it was the turbocharger turbine model that performed in anon-optimal way. To cope with this, the turbine model containedparameters, which could be adjusted so that the model resultsmatched measured data. However, it was absolutely necessary tohave measured data to match against. It was thus concluded thatthe predictivity of the software tool was too poor to try topredict the performance of various boosting systems. Thereforemeans of improving the modelling procedure were investigated.To enable such an investigation a technique was developed tomeasure the instantaneous power output from, and efficiency of,the turbine when the turbocharger was used on the engine. The project’s initial aim was to predict, throughsimulations, the best way to boost a downsized SI-engine with avery high boost-pressure demand. The first simulation run on astandard turbocharged engine showed that this could not be donewith any high accuracy. However, a literature study was madethat presents various different boosting techniques that canproduce higher boost pressure in a larger flow-range than asingle turbocharger, and in addition, with smallerboost-pressure lag. <b>Key words:</b>boosting, turbocharging, supercharging,modelling, simulation, turbine, pulsating flow, unsteadyperformance, SI-engine, measurement accuracy / NR 20140805

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / In Latin America, the lack of electricity has been a serious problem for over several years. To overcome this lack of supply in electricity supply, hydraulic energy is now being used in a greater proportion to fulfill the electricity needs in the rural areas. Investigations have been conducted to assess the environmental conditions of these rural areas to optimize the functionality of turbines used for hydraulic energy generation. However, there are very few focused on turbines of less than 0.5 kW generation. The proposed study aims to analyze the positioning of the blades of the cross-flow turbines and designing an electric generation system for rural dwellings. A simulation of each evaluated design was performed, and the power generated from these turbines was calculated. The results show that the power outputs initially were high and stabilized at a value of approximately 180 W, hence satisfying the minimum demands of a rural house.

An experiment was conducted to investigate the aerodynamic losses of two high-pressure steam turbine nozzles (526A, 525B) subjected to a large range of incident angle and exit Mach number. The blades were tested in a 2D transonic windtunnel. The exit Mach number ranged from 0.60 to 1.15 and the incidence was varied from -34o to 35o. Measurements included downstream Pitot probe traverses, upstream total pressure, and endwall static pressures. Flow visualization techniques such as shadowgraph photography and color oil flow visualization were performed to complement the measured data. When the exit Mach number for both nozzles increased from 0.9 to 1.1, the total pressure loss coefficient increased by a factor of 7 as compared to the total pressure losses observed at subsonic condition (M2<0.9). For the range of incidence tested, the effect of flow incidence on the total pressure losses is less pronounced. Based on shadowgraphs taken during the experiment, it's believed that the large increase in losses at transonic conditions is due to strong shock/boundary layer interaction that may lead to flow separation on the blade suction surface. From the measured total pressure coefficients, a modified loss model that accounts for higher losses at transonic conditions was developed. The new model matches the data much better than the existing Kacker-Okapuu model for transonic exit conditions. / Master of Science