The purpose of this thesis has been to evaluate the use of a swirl blade in the uphill teeming process through plant trials. Two series of trials were carried out at Scana Steel Stavanger AS. In the trials a divergent entrance nozzle with a 62° outlet angle were used when casting duplex stainless steel on a base plate with two 6.2 tons ingots. All molds were burned onto the ingots; leading to problems with emptying the ingots from the molds and severe damages on the molds. To get a better insight during the casting and understand why the molds were burned onto the ingots; during the second series of trials one mold on each base plate were filmed in the beginning of the casting process. Evaluation of the castings indicated that splashing on the mold wall at an initial stage was one reason for the mold burned onto the ingot. Further, material samples were collected to evaluate the non-metallic inclusion composition and distribution with SEM when casting with a swirl blade compared to when casting without. The area percentage of the inclusions in the samples was 1% and 2% for samples casted with and without swirl blade respectively with d=2.8 mm. The inclusion size also varied for samples casted with and without swirl blade; 98% of the inclusions were in the size range of 0-10 μm when casted with and in the size range 0-20 μm when casted without swirl blade. / Syftet med denna uppsats har varit att utvärdera användningen av swirlblad i götgjutningsprocessen. Två serier med försök har utförts på Scana Steel Stavanger AS. I försöken användes en inloppssten med 62°-vinklat utlopp, där duplexa rostfria stål göts på stigplan med två 6,2 tons kokiller. Alla kokiller brände fast på göten, vilket ledde till svårigheter vid urtag av göten samt skador på kokillerna. För att få en bättre förståelse av varför kokillerna brände fast, filmades ett göt på vardera stigplan under den andra försöksserien. Utvärdering av försöken indikerar att en anledning till att kokillerna brände fast på göten var att det stänkte upp stål på kokillväggen i ett tidigt stadium. Vidare har materialprover samlats in för att utvärdera sammansättningen samt utspridningen av icke-metalliska inneslutningar i SEM då göt gjutits med swirlblad jämfört med utan. Area procenten i proverna var 1% och 2% då proverna gjutits med respektive utan swirlblad, med d=2.8 mm. Även storleken på inneslutningarna i prover som gjutits med och utan swirlblad skiljde sig åt, 98% av inneslutningarna var i storleksintervallet 0-10 μm för prover gjutna med swirlblad medan de som gjutits utan var i storleksintervallet 0-20 μm. / JK24053

Modern gas turbine blades and vanes are operated at temperatures above their material’s melting point. Active external and internal cooling are therefore necessary to reach acceptable lifetimes. One possible internal cooling method is called matrix cooling, where a matrix of intersecting cooling air channels is integrated into a blade or vane. To further increase the efficiency of gas turbines, the amount of cooling air must be reduced. Therefore it is necessary that heat transfer inside a cooling matrix is well understood. In the first part of the thesis, a methodology for estimating heat transfer in the flow of matrix cooling channels was established using Computational Fluid Dynamics. Two four-equation RANS turbulence models based on the k-ε turbulence model showed a good correlation with experimental results, while the k-ω SST model underpredicted the heat transfer significantly. For all turbulence models, the heat transfer showed high sensitivity towards changes in the numerical setup. For the k-ω SST turbulence model, the mesh requirements were deemed too computationally expensive and it was excluded from further investigations. As the second part of the thesis, a parameter study was conducted investigating the influence of several geometric parameters on the heat transfer in a cooling matrix. The matrix was simplified as a channel flow interacting with multiple crossing flows. The highest enhancement in heat transfer was seen with changes in taper ratio, aspect ratio and matrix angle. Compared to smooth pipe flow, an increase in heat transfer of up to 60% was observed. Rounded edges of the cooling channels showed a significant influence on the heat transfer as well. In contrast, no influence of the wall thickness on the heat transfer was observed. While no direct validation is possible, the base case and the parameter sweeps show a good correlation with similar cases found in the literature.

This dissertation presents an approach to use blade tip timing measurements with finite element analysis to predict the fatigue life of a low pressure steam turbine last stage blade under high backpressure and low flow conditions. Material fatigue properties were determined through the extended universal material law for FV566 material, along with different temper scenarios. A finite element model of a blade with damping pins was developed, using the principle of cyclic symmetry for a perfectly tuned model. Pre-stress modal analysis was conducted, incorporating damping via friction and plasticity for initial 20% overspeed test. The finite element model was verified by two experimental tests: the first being a blade impact test and the second a telemetry strain gauge test in a balance pit. Fatigue life analysis was conducted under the assumption that non-synchronous vibration is experienced by the blade and that only one mode is dominant in the vibration. The results from the fatigue analysis corresponded to the location of the cracks experienced on the blades. The results show twelve orders of magnitude lower life at low load, high backpressure conditions, compared to high load high pressure conditions. The research was further extended to check the same vibratory response on the first three modes, up to their tenth nodal diameters. This was done to analyse fatigue life in a case that a different mode was excited. / Dissertation (MEng)--University of Pretoria, 2020. / Eskom Rotek Industries / Mechanical and Aeronautical Engineering / MEng / Unrestricted

Tropical regions currently receive the highest global levels of solar ultraviolet-B radiation (UV-B, 280-320 nm) even without ozone depletion. Thus, the influence of natural, present-day UV-B irradiance in the tropics was examined for five tropical species, including three native rainforest tree species and two economically important species. Solar UV-B radiation conditions were obtained vi using either a UV-B excluding plastic film or a near-ambient UV-B transmitting film in a small clearing on Barro Colorado Island (BCI), Panama (9 ° N). Significant differences were often exhibited as increased foliar UV-B absorbing compounds, increased leaf mass per area, and reduced leaf blade length for plants receiving solar UV-B radiation. Plant height was typically reduced under solar UV-B, but some variation among species in response was seen. Biomass and photosystem II function using chlorophyll fluorescence were generally unaffected. The results of this study provide strong evidence that tropical vegetation, including native rainforest species, responds to the present level of natural solar UV-B. This suggests that even a small increase in UV-B radiation with ozone depletion may have biological implications.

A recombinat Chinese Hamster Ovary (rCHO) cell line designated as CHO SEAP was utilized in this investigation to optimize protein production. Two bench top stirred-tank bioreactors, namely a pitched-blade and a packed-bed basket bioreactor, were utilized for a comparative study to determine which bioreactor would produce the best results in terms of protein production. The objective of this research project was to provide basic data that shows cells cultured in a packed-bed basket bioreactor in perfusion mode will generate more protein product than cells in batch mode suspension culture with a pitched-blade bioreactor. The packed-bed bioreactor creates a homeostatic environment similar to the environment found in vivo, where waste products are constantly removed and fresh nutrients are replenished. Closed batch cultures do not provide a homeostatic environment. In batch culture systems, nutrients are depleted and waste products accumulate. The results from this experiment could help investigators involved in protein and/or vaccine production facilities select the appropriate bioreactor and mode of operation to optimize cell productivity for generation of a specific protein product. CHO cells have been used for the production of vaccines, recombinant therapeutic proteins, and monoclonal antibodies, and these cells are now the cell line of choice in the biopharmaceutical industry. Traditional vaccine production methods in egg embryos are slow and outdated, whereas roller bottle-based cell culture techniques are time consuming and have limited scalability. These limitations justify the need for development of stirred tank bioreactors. Cells cultured in a packed-bed bioreactor are not exposed to hydrodynamic forces, as is the case with pitched-blade bioreactors, allowing for maximum growth and protein expression. This mode of operation involves the constant removal of media depleted of nutrients and the addition of fresh media with more nutrients to keep the cells growing. Long run times decrease the constant need for re-seeding cells and re-establishing seed cultures, thus, reducing setup time and labor dramatically. Secreted products are automatically separated from cells in perfusion, eliminating filtration and membrane fouling. A detailed description of both modes of operation are discussed in this thesis.

No description available.

This thesis consists of a detailed analysis of different blade testing methods and improvements to a novel concept for tri-axial testing of large wind turbine blades. As the blades are one of the most critical components of the wind turbine, they have to be tested in order to ensure that their specifications are consistent with the actual performance of the blade. It must be demonstrated that the blade can withstand both the ultimate loads and the fatigue loads to which the blade is expected to be subjected during its design service life. There are basically two types of blade testing: static testing and fatigue testing. Testing of the blades statically and dynamically helps in improving the designs and the manufacturing processes. This thesis has two objectives. The first objective is to document the assumptions, calculations and results of an initial sizing of a bell crank system for testing blades 50m, 60m and 70m long. The second objective of this report is to document the modeling of one of the alternatives to bell crank system in SolidWorks. The thesis ends with conclusions and suggestions for future work. An advanced blade testing method which can be used for large wind turbine blades is developed and so are the system requirements. The concept is used to excite the blade in flapwise and edgewise direction simultaneously. The flap motion of the blade is caused by BREX resonant technology, which is already used by National Renewable Energy Laboratory (NREL) in Colorado, and edgewise motion is delivered by the use of two inclined hydraulic actuators and linear guide rail system is used to move the inclined actuators in the flapwise direction along the blade motion. The hydraulic system and linear guide rail requirements are analyzed and discussed. The design is discussed and analyzed in detail proving it to be feasible. The cost estimation is done for the design. It is recommended for implementation as it will serve as an efficient way of testing large wind turbine blades.

Over recent years, offshore wind energy has been growing around the world. This necessitates placing wind turbines directly in or near the oceans where hurricanes can be. Previous research has suggested that hurricane wind veer and direction change can have adverse loading effects on the turbine. Such effects can create damage to the blade or worsen existing ones. Currently, there is no known design standard for addressing wind veer and direction change specifically from hurricanes. Quantifying the loading contribution from these phenomena is not abundant either. This thesis seeks to demonstrate a proposed procedure for defining design veer profiles and direction changes from hurricanes using statistical averages and percentiles of veer and direction change magnitudes. Using simulated wind field data that describes a stationary Category 5 hurricane, the maximum veer profiles and direction changes will first be determined. Methods for statistically characterizing these wind field phenomena will be applied to provide design veer profiles and direction changes. These maximum and design veer profiles and direction changes will be applied to a feathered IEA-15MW turbine blade at 0 and 180 degrees azimuth, and the effects on the static blade loadings will be examined using blade element theory. Baseline scale factors describing the loading increase from veer or direction change will be established for the maximum and design veer profiles and direction changes. Rated scale factors describing the loading increase from veer and wind speed or direction change and wind speed relative to the rated condition loadings will also be established. The purpose of these scale factors is to estimate increases in loads from these wind field characteristics and not be directly used in any serious wind blade design. This thesis will show that hurricane wind veer and direction change can each, individually, increase the blade loading greater than the wind velocity can on a feathered blade. The wind speed/wind veer loadings can induce resultant moments up to 2.5 times rated with veer contributing 87.5% of the increased loading while the wind speed / direction change loadings can induce resultant moments up to 2.8 times rated with direction change contributing 88.8%.

Experiments have been performed using the Air Force Research Laboratory (AFRL) Blade-Row Interaction (BRI) rig to investigate interactions between a loaded stator and transonic rotor. The BRI rig is a high-speed, highly loaded compressor consisting of a swirler/deswirler, a transonic rotor and a stator. The swirler/deswirler of the BRI rig is used to simulate an embedded transonic fan stage with realistic geometry which produces a wake through diffusion. Details of the unsteady flow field between the stator and rotor were obtained using Particle Image Velocimetry (PIV). Flow visualization images and PIV data that facilitate analysis of vortex shedding, wake motion, and wake-shock-interactions in the blade row are analyzed for three stator/rotor axial spacings and two stator loadings. The data analysis focuses on measuring and comparing, for the different spacings and loading, the vortex size, strength, and location as it forms on the stator trailing edge and propagates downstream into the rotor passage. It was observed that more than one vortex was shed with the passing of a rotor bow shock. These vortices were categorized as small and large vortices with a ~20% decrease in strength. The large vortices were compared at similar location and results show that vortex strength increased as spacing between stator and rotor decreased due to the increased strength of the rotor bow shock impacting the stator trailing edge. Changes in stator loading also affected shed vortex strength. A decrease in stator loading resulted in a decrease in the strength of the vortex shed. The smaller vortices were not affected by a change in spacing but strength was directly related to the loading.

A shrouded blade was designed as a test case for flutter analysis of steam turbine. Flutter is a self-excitedvibration. It can lead to dramatic blade loss and high-cycle fatigue. Shrouded blade is more complicated onflutter analysis, because the mode shapes are more complex with bending and torsion components atdifferent phases. Moreover, the blade mode shape and frequency also vary with nodal diameter. Lack ofopen resource of shrouded blade, there were less researches about shrouded blade test case on flutter. The initial blade geometry was from Di Qi’s 3D free standing blade test case. The material of the blade isTitanium. The aim of current study is to design a 3D test case for realistic shrouded blade flutter analysis. The geometryof the proposed shrouded blade test case was fully described in this thesis report. ANSYS ICEM was usedfor presenting the geometry and generating mesh. ANSYS APDL was used for structural analysis.Parameters of shroud parts were based on literature reviews and engineers’ general suggestions. The modeshapes for the first family of modes were calculated and reported. / Ett höljeblad utformades som ett testfall för fladderanalys av ångturbin. Flutter är en självupphetsadvibration. Det kan leda till dramatisk bladförlust och högcykelutmattning. Höljeblad är mer kompliceratvid fladderanalys, eftersom modeformerna är mer komplexa med böjnings- och torsionskomponenter iolika faser. Dessutom varierar bladformsformen och frekvensen också med noddiameter. Brist på öppenresurs av höljet blad, det fanns mindre undersökningar om höljet blad test fall på flutter. Den ursprungligabladgeometrin var från Di Qis 3D frittstående bladprovfall. Bladets material är titan. Syftet med den aktuella studien är att designa ett 3D-testfall för realistisk hävd bladflöjtsanalys. Geometrinhos det föreslagna höljet av bladsprov beskrivs fullständigt i denna avhandlingsrapport. ANSYS ICEManvändes för att presentera geometrin och det genererande nätet. ANSYS APDL användes för strukturellanalys. Parametrar av höljesdelar baserades på litteraturrecensioner och ingenjörers allmänna förslag.Modeshistorierna för den första familjen av lägen beräknades och rapporterades.