Methodology for wind turbine blade geometry optimization

Nowadays, the upwind three bladed horizontal axis wind turbine is the leading player on the market. It has been found to be the best industrial compromise in the range of different turbine constructions. The current wind industry innovation is conducted in the development of individual turbine components. The blade constitutes 20-25% of the overall turbine budget. Its optimal operation in particular local economic and wind conditions is worth investigating. The blade geometry, namely the chord, twist and airfoil type distributions along the span, responds to the output measures of the blade performance. Therefore, the optimal wind blade geometry can improve the overall turbine performance. The objectives of the dissertation are focused on the development of a methodology and specific tool for the investigation of possible existing wind blade geometry adjustments. The novelty of the methodology presented in the thesis is the multiobjective perspective on wind blade geometry optimization, particularly taking simultaneously into account the local wind conditions and the issue of aerodynamic noise emissions. The presented optimization objective approach has not been investigated previously for the implementation in wind blade design. The possibilities to use different theories for the analysis and search procedures are investigated and sufficient arguments derived for the usage of proposed theories. The tool is used for the test optimization of a particular wind turbine blade. The sensitivity analysis shows the dependence of the outputs on the provided inputs, as well as its relative and absolute divergences and instabilities. The pros and cons of the proposed technique are seen from the practical implementation, which is documented in the results, analysis and conclusion sections.

Pneumatic Conveying of Granular Materials in a Pilot Scale Downer-Riser System

Studies regarding the field of this work aim to substitute industrial mechanical conveyors with pneumatic conveyors to overcome the disadvantages in solids flow regulation and risks posed to production and health. The experimental part of this work examines how the granular material properties, fluidizing airflow rate, equipment geometry, and pressures along the pipes affect the mass flow rate through the system. The results are compared with those obtained from previous experiments conducted with alumina. Experiments were carried out with a pilot scale downer-riser system at Outotec Research Center Frankfurt. Granular materi-als used in this work are named as sand, ilmenite, iron ore 1 and iron ore 2.

Woodland Sketches, Op. 51

Soitinnus: Piano.

Performance Improvement of Centrifugal Compressor Stage with Pinched Geometry or Vaned Diffuser

Centrifugal compressors are widely used for example in refrigeration processes, the oil and gas industry, superchargers, and waste water treatment. In this work, five different vaneless diffusers and six different vaned diffusers are investigated numerically. The vaneless diffusers vary only by their diffuser width, so that four of the geometries have pinch implemented to them. Pinch means a decrease in the diffuser width. Four of the vaned diffusers have the same vane turning angle and a different number of vanes, and two have different vane turning angles. The flow solver used to solve the flow fields is Finflo, which is a Navier-Stokes solver. All the cases are modeled with the Chien's k – έ- turbulence model, and selected cases are modeled also with the k – ώ-SST turbulence model. All five vaneless diffusers and three vaned diffusers are investigated also experimentally. For each construction, the compressor operating map is measured according to relevant standards. In addition to this, the flow fields before and after the diffuser are measured with static and total pressure, flow angle and total temperature measurements. When comparing the computational results to the measured results, it is evident that the k – ώ-SST turbulence model predicts the flow fields better. The simulation results indicate that it is possible to improve the efficiency with the pinch, and according to the numerical results, the two best geometries are the ones with most pinch at the shroud. These geometries have approximately 4 percentage points higher efficiency than the unpinched vaneless diffusers. The hub pinch does not seem to have any major benefits. In general, the pinches make the flow fields before and after the diffuser more uniform. The pinch also seems to improve the impeller efficiency. This is down to two reasons. The major reason is that the pinch decreases the size of slow flow and possible backflow region located near the shroud after the impeller. Secondly, the pinches decrease the flow velocity in the tip clearance, leading to a smaller tip leakage flow and therefore slightly better impeller efficiency. Also some of the vaned diffusers improve the efficiency, the increment being 1...3 percentage points, when compared to the vaneless unpinched geometry. The measurement results confirm that the pinch is beneficial to the performance of the compressor. The flow fields are more uniform with the pinched cases, and the slow flow regions are smaller. The peak efficiency is approximately 2 percentage points and the design point efficiency approximately 4 percentage points higher with the pinched geometries than with the un- pinched geometry. According to the measurements, the two best geometries are the ones with the most pinch at the shroud, the case with the pinch only at the shroud being slightly better of the two. The vaned diffusers also have better efficiency than the vaneless unpinched geometries. However, the pinched cases have even better efficiencies. The vaned diffusers narrow the operating range considerably, whilst the pinch has no significant effect on the operating range.

Blomberg-lauluja, op. 51:1

Digitoitu 13. 8. 2008.

Blomberg-lauluja, op. 51:2

Digitoitu 13. 8. 2008.

Gutenberg 1900:50 – 51

Gutenberg-lehti ilmestyi vuosina 1893-1915. Se oli perustettu ammattilehdeksi ja yhdyssiteeksi Suomen kirjanpainajille sekä äänenkannattajaksi Suomen kirjaltajaliitolle.

New computer software for defining the three-dimensional geometry for a centrifu- gal compressor impeller

In this thesis, a computer software for defining the geometry for a centrifugal compressor impeller is designed and implemented. The project is done under the supervision of Laboratory of Fluid Dynamics in Lappeenranta University of Technology. This thesis is similar to the thesis written by Tomi Putus (2009) in which a centrifugal compressor impeller flow channel is researched and commonly used design practices are reviewed. Putus wrote a computer software which can be used to define impeller’s three-dimensional geometry based on the basic geometrical dimensions given by a preliminary design. The software designed in this thesis is almost similar but it uses a different programming language (C++) and a different way to define the shape of the impeller meridional projection.

Blomberg-lauluja, op. 51:5

Soitinnus: lauluääni, piano.

8/2010 Kantatien 51 Kirkkonummi-Kivenlahti vaikutusselvitys

Tässä työssä on arvioitu moottoritieksi rakenteilla olevan kantatie 51 Kirkkonummi-Kivenlahti-tieosuuden vaikutuksia liikenteeseen sekä alueen kehitykseen. Työssä käytetyt aineistot koostuvat yleisesti saatavilla olevista tilastoista ja rekistereistä. Lisäksi toteutuneita ja odotettavissa olevia vaikutuksia on selvitetty kunta- ja yrityshaastattelujen avulla. Nyt toteutetussa ennen-vaiheessa havaittuja hankkeen orastavia vaikutuksia sekä moottoritieyhteyteen liittyviä odotuksia on nostettu esiin. Ennen-vaiheen tiedonkeruu muodostaa jälkeen-vaiheen vaikutusarvioinnin rungon. Varsinaiset johtopäätökset voidaan tuottaa jäkeen-vaiheen vaikutusarvioinnin yhteydessä. Ympäristövaikutukset on jätetty tarkastelun ulkopuolelle. Moottoritieyhteyden valmistumisen myötä liikenteen sujuvuus, turvallisuus ja ajomukavuus paranevat etenkin liittymissä. Nopeutuva ja sujuvoituva liikenneyhteys helpottaa etenkin tien länsiosien asukkaiden autoillen tapahtuvaa työssäkäyntiä pääkaupunkiseudulla ja lisää asiointia tien varren keskuksissa. Myös etenkin viikonloppuisin tapahtuva mökki- ja muu vapaa-ajanliikenne hyötyy merkittävästi tien paranemisesta. Yritysasiointi ja muut lyhytkestoiset pistäytymiset autolla pääkaupunkiseudun ja tarkastelualueen länsiosan välillä sujuvoituvat matka-aikojen muuttuessa nopeammiksi ja helpommin ennustettaviksi. Nämä hyödyt koskevat myös raskasta liikennettä ja muita kuljetuksia. Moottoritien valmistuminen Kirkkonummenja Kivenlahden välille parantaa linja-autoliikenteen liikennöintiolosuhteita. Merkittävintä on täsmällisyyden lisääntyminen ruuhkien vähentyessä sekä tielle liittymisen helpottuessa. Lisäksi tien tuoma hienoinen matka-aikojen lyhentyminen synnyttää myös suoria aikasäästöjä. Moottoritie parantaa suhteellisesti eniten henkilöautoliikenteen sujuvuutta, ja ilman muita toimenpiteitä tämä saattaa johtaa joukkoliikenteen kulkutapaosuuden supistumiseen. Moottoritieyhteys lisää muuttoliikettä tienvarteen liikenteellisesti ja asuinympäristöltään edullisille alueille. Jo tien rakentamispäätös on vaikuttanut tienvarsialueen houkuttelevuuteen asuinpaikkana. Tarkastelualueen kuntien nettomuutto on ollut koko 2000-luvun selvästi positiivinen. Väestönkasvu on ollut joka kunnassa 1-3 % vuodessa. Voimakas muuttoliike luo kuitenkin ankariakin paineita kuntatalouteen palvelutarjonnan ja kunnallistekniikan lisäystarpeen vuoksi. Alueen kunnissa pientalojen hinnannousut ovat olleet suhteellisen säännönmukaisia. Kantatie 51 muodostaa alueellisesti merkittävän kehityskäytävän, jonka maankäyttöä tien parantamisen viivästyminen on rajoittanut lähinnä Kirkkonummen alueella. Tien tuntumassa on käynnissä lukuisia kaavoitushankkeita, joiden tavoitteena on keskittää asutusta ja yritystoimintaa tien ja rantaradan muodostamaan kehityskäytävään. Espoossa Länsiväylän varren työpaikka-alueen odotetaan täydentyvän moottoritien jatkamisen myötä. Siuntiossa ja Inkoossa kaavoituksella osoitetaan lisää maankäyttöä tien tuntumaan. Haastatelluissa yrityksissä tien parantamista pidetään myönteisenä, imagoa parantavana ja toimintaoloja helpottavana kehityksenä. Etenkin niiden yritysten, joilla on kiinteät yhteydet pääkaupunkiseutuun, toimintaedellytykset paranevat liikkumisen nopeutumisen ja asioinnin helpottumisen myötä. Kuljetuksia helpottaa etenkin liittymien parantaminen ja matka-aikojen ennakoitavuus. Kaupan edellytykset paranevat etenkin Kirkkonummella, jonne on suunnitteilla tilaa vievän kaupan yksiköitä. Lisäksi tieyhteyden parantamisella odotetaan olevan myönteinen vaikutus matkailu- ja vapaa-ajan palvelujen kuten retkeily-, golf- ja veneilymahdollisuuksien kysyntään.

Two-phase flow measurements with spacer grid in a rod bundle geometry

Heat transfer effectiveness in nuclear rod bundles is of great importance to nuclear reactor safety and economics. An important design parameter is the Critical Heat Flux (CHF), which limits the transferred heat from the fuel to the coolant. The CHF is determined by flow behaviour, especially the turbulence created inside the fuel rod bundle. Adiabatic experiments can be used to characterize the flow behaviour separately from the heat transfer phenomena in diabatic flow. To enhance the turbulence, mixing vanes are attached to spacer grids, which hold the rods in place. The vanes either make the flow swirl around a single sub-channel or induce cross-mixing between adjacent sub-channels. In adiabatic two-phase conditions an important phenomenon that can be investigated is the effect of the spacer on canceling the lift force, which collects the small bubbles to the rod surfaces leading to decreased CHF in diabatic conditions and thus limits the reactor power. Computational Fluid Dynamics (CFD) can be used to simulate the flow numerically and to test how different spacer configurations affect the flow. Experimental data is needed to validate and verify the used CFD models. Especially the modeling of turbulence is challenging even for single-phase flow inside the complex sub-channel geometry. In two-phase flow other factors such as bubble dynamics further complicate the modeling. To investigate the spacer grid effect on two-phase flow, and to provide further experimental data for CFD validation, a series of experiments was run on an adiabatic sub-channel flow loop using a duct-type spacer grid with different configurations. Utilizing the wire-mesh sensor technology, the facility gives high resolution experimental data in both time and space. The experimental results indicate that the duct-type spacer grid is less effective in canceling the lift force effect than the egg-crate type spacer tested earlier.

Defining the keyhole modes – the effects on the weld geometry and the molten pool behaviour in high power laser welding of stainless steels

Keyhole welding, meaning that the laser beam forms a vapour cavity inside the steel, is one of the two types of laser welding processes and currently it is used in few industrial applications. Modern high power solid state lasers are becoming more used generally, but not all process fundamentals and phenomena of the process are well known and understanding of these helps to improve quality of final products. This study concentrates on the process fundamentals and the behaviour of the keyhole welding process by the means of real time high speed x-ray videography. One of the problem areas in laser welding has been mixing of the filler wire into the weld; the phenomena are explained and also one possible solution for this problem is presented in this study. The argument of this thesis is that the keyhole laser welding process has three keyhole modes that behave differently. These modes are trap, cylinder and kaleidoscope. Two of these have sub-modes, in which the keyhole behaves similarly but the molten pool changes behaviour and geometry of the resulting weld is different. X-ray videography was used to visualize the actual keyhole side view profile during the welding process. Several methods were applied to analyse and compile high speed x-ray video data to achieve a clearer image of the keyhole side view. Averaging was used to measure the keyhole side view outline, which was used to reconstruct a 3D-model of the actual keyhole. This 3D-model was taken as basis for calculation of the vapour volume inside of the keyhole for each laser parameter combination and joint geometry. Four different joint geometries were tested, partial penetration bead on plate and I-butt joint and full penetration bead on plate and I-butt joint. The comparison was performed with selected pairs and also compared all combinations together.

Unequal Teeth Widths for Torque Ripple Reduction in Permanent Magnet Synchronous Machines With Fractional-Slot Non-Overlapping Windings

Permanent magnet synchronous machines with fractional-slot non-overlapping windings (FSPMSM), also known as tooth-coil winding permanent magnet synchronous machines (TCW PMSM), have been under intensive research during the latest decade. There are many optimization routines explained and implemented in the literature in order to improve the characteristics of this machine type. This paper introduces a new technique for torque ripple minimization in TCW PMSM. The source of torque harmonics is also described. The low order torque harmonics can be harmful for a variety of applications, such as direct drive wind generators, direct drive light vehicle electrical motors, and for some high precision servo applications. The reduction of the torque ripple harmonics with the lowest orders (6th and 12th) is realized by machine geometry optimization technique using finite element analysis (FEA). The presented optimization technique includes the stator geometry adjustment in TCW PMSMs with rotor surface permanent magnets and with rotor embedded permanent magnets. Influence of the permanent magnet skewing on the torque ripple reduction and cogging torque elimination was also investigated. It was implemented separately and together with the stator optimization technique. As a result, the reduction of some torque ripple harmonics was attained.