Vertical axis wind turbines (VAWTs) have with time been outrivaled by the today common and economically feasible horizontal axis wind turbines (HAWTs). However, VAWTs have several advantages such as the possibility to put the drive train at ground level, lower noise emissions and better scaling behavior which still make them interesting for research. The work within this thesis is made in collaboration between the Department of Construction and Energy Engineering at Halmstad University and the Division for Electricity at Uppsala University. A 200 kW VAWT owned by the latter and situated close to Falkenberg in the southwest of Sweden has been the main subject of the research even if most learnings has been generalized to fit a typical vertical turbine. This particular turbine has a wooden tower which is semi-guy-wired, i.e. the tower is both firmly attached to the ground and supported by guy-wires. This thesis has two main topics both regarding VAWTs: eigenfrequency of the tower and the noise generated from the turbine. The eigenfrequency of a semi-guy-wired tower is studied and an analytical expression describing this is produced and verified by experiments and simulations. The eigenfrequency of the wire itself and how it is affected by wind load are also studied.  The noise characteristics of VAWTs have been investigated, both theoretically and by noise measurement campaigns. Both noise emission and frequency distribution of VAWTs has been studied. The work has resulted in analytical expressions for tower and wire eigenfrequency of a semi-guy-wired tower as well as recommendations for designing future towers for VAWTs. The noise emission of VAWTs has been studied and proven low compared to HAWTs. The noise frequency distribution of the 200 kW VAWT differs significantly from that of a similar size HAWTs with for example lower levels for frequencies below 3000 Hz.

No description available.

Heat transfer inside rotating coolant channels have a significant impact in design of gas turbine airfoils and other rotating components such as generator windings.  The effects of the Coriolis acceleration and centrifugal buoyancy have a significant impact on heat transfer behavior inside such rotating coolant channels due to the complex flow patterns of coolant.  Detailed heat transfer knowledge greatly enhances the designers\' ability to validate numerical models of newly designed channels. A rotating experimental rig was designed and built to model scaled up coolant channels at speeds up to 750 rotations per minute (rpm).  A camera is mounted onto the rotating test section and a transient liquid crystal technique is used to measure detailed heat transfer coefficients on a surface of interest.  The experimental set-up is innovative, as it involves no surface heating of the test section, very little instrumentation beyond a few thermocouples and a spray coating of thermochromic liquid crystals on the test surface.  To validate the test rig and the experimental method, multipass coolant channels with rib turbulators, large diameter radially outward channels with rib turbulators, and jet impingement cooling schemes are studied during rotation.  90deg, W, and M-shaped rib enhancements are studied and detailed heat transfer measurements clearly capture the heat transfer enhancement mechanisms with and without rotation.  Jet impingement schemes with single and double rows, normal and off-angle jets, and a cross flow outlet condition are all studied under rotation.  Non-rotating studies are also performed for baseline comparisons to rotating conditions.  Large aspect ratio, diverging channels with dimple and rib turbulators are studied in a stationary condition.  Results for all different test geometries show good comparisons with published studies indicating that the rotating rig and experimental method are valid.  Jet impingement schemes produce higher heat transfer compared to the two-pass channels with ribs, however pressure losses are significantly higher.  The fewer the jets and H/d=1 produces the highest pressure losses with no significant gain in heat transfer.  Off angle jets at H/d=1 produces very high pressure losses with no heat transfer advantage.  A final study with radially outward coolant channels is performed with the highest rotation speeds.  The structure, test section, and camera are thoroughly designed to withstand the exceptional g-forces.  Heat transfer in the radial channels with and without rotation show very little effect of rotation due to the small rotation number. / Ph. D.

The goal of this research has been the development of an effective design tool for torsional analysis. In the hopes of achieving this goal the computer program, Torsion 1, has been created. This torsional transfer matrix program provides the user with the ability to easily model multi-rotor systems using a simple user-interface. The program is capable of modeling such components or system characteristics as continuously distributed mass, viscous and structural damping, vibration absorbers, and gear meshes with gear tooth flexibility. The analysis capabilities of the program include forcedresponse and free-vibration analyses. The forced-response analysis module is capable of determining a system’s response to a static or harmonic torsional load. The free-vibration analysis module allows is capable of determining the eigenvalues and eigenvectors for damped and undamped systems. This thesis includes an explanation of the multi-rotor transfer matrix technique employed in Torsion 1. The derivation of transfer matrices for visco-elastic vibration absorbers, pendulum absorbers, flexible gear meshes, and planetary gear trains are included in this work. Finally, the validity of the program results is verified with a set of benchmark examples. / Master of Science

In this work, research to develop algorithms for a package exchange maneuver between two quad-rotor aircraft is presented. First, the development of tools used for this research is discussed. Second, a controller is designed that synchronizes the flight paths and motion of two quad-rotor robots. The controller is used to guide a designated follower quad-rotor to follow a leader aircraft’s position and orientation. The follower aircraft is equipped with a simple mechanical manipulator to compensate for limitations in the aircrafts maneuverability. finally, a sensor architecture study for relative navigation of Unmanned Aerial Vehicles (UAV) is presented. The architecture study presents typical navigation solutions, considers each solution’s appropriateness for close-proximity missions, and compares performance.

På SSI-Schäfer System International i Norrköping pågår ständiga förbättringar och projektför att effektivisera produktionen hos kunden. Ett förbättringsområde som varit särskiltintressant under senare tid har varit produktionsflödet mellan lagerhanteringssystemet(shuttlesystemet) och packningsstationerna och på packningsstationerna. Den här rapportenpresenterar en fallstudie om förbättringspotential och åtgärder för förbättringspotential,baserat på befintlig företagsdokumentation och intervjuer på företaget, samt kartläggningarav produktionsflödet hos kunden. Genomförandet av studien är uppdelat i fyra huvudfaser, I.Kartläggning av produktionen, II. Presentation av identifierade förbättringspotential ochslöseri, III. Identifiering av rotorsaker till förbättringspotential och slöseri och IV.Framtagning av förbättringsförslag. De två första faserna är att förstå produktionen ochpresentera identifierade förbättringspotential och slöseri. I tredje fasen identifieras rotorsakertill förbättringspotential och slöseri, i fjärde fasen presenteras förbättringsförslag.Presentation av identifierade förbättringspotential och slöseri resulterade i att projektet kundefokusera på 5 viktiga förbättringspotentialer, 1. Deadlocks (dödläge), 2. Backar som fastnar,3. Dra stora kartongen, 4. Stopp sekvenserare 1, 5. Skrivare vid GTP-stationer(packningsstationer). Identifiering av rotorsaker till förbättringspotential och slöserigenomfördes med hjälp av Ishikawadiagram för varje förbättringspotential tillsammans medoperatörer på GTP-stationerna och RM-teamet. Detta resulterade i 1. Brist på vänteplatser, 2.Viktfördelning i backarna, 3. Operatörerna saknar åtkomst till transportbandet, 4. Backarloopas inte, 5. Placering av skrivare. För att ta itu med förbättringspotentialen föreslogsföljande förbättringar: 1. Bygg en till lift, 2. Montera bricka och plugg, 3. Justeraautobagmaskinen, 4. Cirkulera (loopa) backarna, 5. Placera skrivare på bordsförlängning ellerhylla närmare operatörer vid GTP-stationer. Det rekommenderas att företaget fortsätter sittarbete genom att ytterligare undersöka föreslagna förbättringsförslag för att implementeraförbättringsförslag för att reducera förbättringspotentialen och slöserier. / At SSI-Schäfer System International in Norrköping, continuous improvements and projectsare underway to streamline the customer's production. An area of improvement that has beenparticularly interesting in recent times has been the production flow between the warehousemanagement system (the shuttle system) and the packing stations and at the packing stations.This report presents a case study on improvement potential and measures for improvementpotential, based on existing company documentation and interviews at the company, as wellas surveys of the production flow at the customer. The implementation of the study is dividedinto four main phases, I. Mapping of production, II. Presentation of identified potential forimprovement and waste, III. Identification of rotor causes for improvement potential andwaste and IV. Development of improvement proposals. The first two phases are to understandthe production and present identified potential for improvement and waste. In the third phase,rotor causes for improvement potential and waste are identified, in the fourth phase,improvement proposals are presented.Presentation of identified improvement potential and waste resulted in the project being ableto focus on 5 important improvement potentials, 1. Deadlocks, 2. Tote boxes that get stuck, 3.Pull the large box, 4. Stop sequencer 1, 5. Printers at GTP-stations (packing stations).Identification of rotor causes for improvement potential and waste was carried out usingIshikawa diagrams for each improvement potential together with operators at theGTP-stations and the RM-team. This resulted in 1. Lack of transferpoints, 2. Weightdistribution in the tote boxes, 3. The operators do not have access to the conveyor belt, 4.Tote boxes are not looped, 5. Placement of printers. To address the potential forimprovement, the following improvements were proposed: 1. Build another lift, 2. Mountwasher and plug, 3. Adjust the autobag machine, 4. Loop the tote boxes, 5. Place printers ontable extensions or shelf closer to operators at GTP-stations. It is recommended that thecompany continue its work by further examining proposed improvement proposals toimplement improvement proposals to reduce the potential for improvement and waste.

Indiana University-Purdue University Indianapolis (IUPUI) / Pressure wave supercharger is an application of wave rotor technology that utilizes compression waves produced by high-pressure engine exhaust gas to compress the fresh intake air within the channels. The phenomena within the wave rotor channels are governed by compression and expansion waves initiated when the channel ends are periodically exposed to differing pressure ports. Two incoming fluids are brought into contact for a very short amount of time to facilitate efficient energy and momentum transfer, thereby exchanging pressure dynamically between the fluids by means of unsteady pressure waves. Since the energy transfer is based on unsteady pressure waves, correct matching of waves and ports is essential for optimum results. Mistiming of the waves in the channels is detrimental to the efficient exchange of pressure and low-pressure exhaust scavenging, which ensures minimum exhaust gas recirculation. Due to varying speed and load conditions of the unit to be supercharged, it is not always possible to maintain the rotor speed constant at the design point. To mitigate the effects of wave mistiming due to varying speed, a well-designed combination of wall-pockets was used in Comprex® pressure wave supercharger. The wall-pockets are the recesses provided in the endplates of pressure wave superchargers to create necessary pressure zones at desired locations. This thesis details an extensive qualitative and computational investigation of the performance of pressure wave superchargers with pockets. Numerical simulations of pressure wave superchargers have been performed using the wave rotor analysis codes employed at the Combustion and Propulsion Research Laboratory at IUPUI. This work also pays close attention to inspecting the numerical schemes and modeling of different physical phenomena used in each code. A comparative verification of the wave rotor analysis codes has been conducted to ensure that the same fundamental numerical scheme is correctly implemented in each code. The issue of low-pressure scavenging has been demonstrated by simulating the four-port (pocketless) pressure wave supercharger operating at lower speeds. The wall-pockets have been modeled using a simple lumped volume technique. The gas state in the lumped volume of pockets is estimated using the continuity and energy equations such that the net mass and energy fluxes between each pocket and the wave rotor channels are close to zero. The lumped volume models of pockets have been implemented in the four-port wave rotor configurations to simulate the pressure wave superchargers with pockets. The simulation results show that the pockets assist to maintain sufficient pressure in the desired zones to facilitate proper low-pressure scavenging during lower rotor speed operations. The Comprex simulation results have been observed to be in good agreement with experimental data and qualitative analysis. Specific observations on the performance of each code and comprehensive simulation results have been presented.

No description available.

In 2013, cracks were found in the radius of the dovetail slots of the rotor rim sheets in generator 1 of Juktan hydro power plant in Västerbotten, Sweden. The cracks were estimated to be too deep to be able to repair and Alstom conducted an investigation on the cause of fracture. The investigation came to the conclusion that the radius was too small and that the new rotor rim sheets should have a six times greater fillet radius. However, it has not been investigated whether the material structure or the manufacturing process may have an impact on the crack initiation and following propagation that is the focus of this report.Parts of the dovetail slots were cut out and characterized with XRF, SEM and LOM. Further mechanical characterizations were done according to Vickers.From the SEM and LOM micrographs a high amount of large (10μm) and cubic particles were found in the microstructure. The micrographs also showed a deformation of the microstructure and the hardness test showed a deformation hardening near the edge where the sheet had been punched. The edge surface of the sheet also had notches.The large and hard particles in the microstructure impair the mechanical properties of the steel. Furthermore, the hardening effect combined with the notches will make a good crack initiation point. Therefore, there is a higher possibility that a crack will initiate in the radius of the dovetail slots where large stresses occur.

The present thesis discusses the forced response of a rotor’s bladed-disk when excited by the periodic force produced by a wake generator, or Inlet Guide Vane (IGV),with 8 equally-spaced blades. These components are part of an axial transonic compressor rig, moreover the Transonic Compressor Darmstadt 1 (TCD1), located at the Technical University of Darmstadt. The investigation is within the ARIAS (Advanced Research Into Aeromechanical Solutions) project, that aims to improve the predictive capabilities of the design methods used in the aircraft propulsion engine’s industry to study aerodynamically induced blade vibrations. The methodology comprised a set of numerical analyses that were conducted using the software Ansys, addressing both the structural and the aerodynamics sides of the aeroelastic problem, in a co-dependent way. At first, steady-state CFD simulations were conducted to study the mesh convergence and to analyse the operation of the compressor at N80 speed, obtaining its compressor map and its peak efficiency operation point. From these, the aerodynamic static force being applied on theblade was obtained, allowing to determine the pre-stresses of the bladed-disk, orblisk. With a modal analysis, the natural modes of the rotor blisk at N80 speed were obtained and the resonance crossing M2 EO8 was identified, plotting the Campbell and ZZENF diagrams. From the modal displacements of the critical mode, a blade flutter analysis was conducted in order to compute the aerodynamic damping ratio of the rotor blisk. With a transient CFD analysis, the periodic forcing being applied onthe rotor blisk that arises from the IGV wake pattern was determined and exported as Fourier coefficients. Finally, a harmonic simulation was carried out to analyse the forced response of the blisk, introducing both the aerodynamic damping value and the unsteady forcing mapped onto the blade. As a result, the frequency response of both the blade maximum alternating deflections and equivalent stresses was obtained, as well as the respective spatial contour plots at the obtained resonance frequency. Some of the results of the conducted analyses were investigated in order to analyse the aerodynamic phenomena occurring, where it was possible to identify vortex shedding, leading shock, tip-clearance and horse-shoe vortex.  Afterwards, the numerical results were compared to the experimental data optained from rig tests conducted at the TCD1 by partners of the ARIAS projects. The numerical model management to predict well the compressor map, thus the steady-state of the flow, as well as the resonance frequency. The aerodynamic damping value was over- predicted when compared to the entire data set. When it came to the harmonic analysis results, the numerical model under-predicted by one order of magnitude the maximum deflection, and the equivalent stress is, as well, far below the experimental results. These results led to conclude that the model is under-predicting the aerodynamix unsteady forcing that results from the wake pattern generated by the IGV and excites the rotor blades.