Axial compressors are widely used in many aerodynamic applications. The design of an axial compressor configuration presents many challenges. Until recently, compressor design was done using 2-D viscous flow analyses that solve the flow field around cascades or in meridional planes or 3-D inviscid analyses. With the advent of modern computational methods it is now possible to analyze the 3-D viscous flow and accurately predict the performance of 3-D multistage compressors. It is necessary to retool the design methodologies to take advantage of the improved accuracy and physical fidelity of these advanced methods. In this study, a first-principles based multi-objective technique for designing single stage compressors is described. The study accounts for stage aerodynamic characteristics, rotor-stator interactions and blade elastic deformations. A parametric representation of compressor blades that include leading and trailing edge camber line angles, thickness and camber distributions was used in this study A design of experiment approach is used to reduce the large combinations of design variables into a smaller subset. A response surface method is used to approximately map the output variables as a function of design variables. An optimized configuration is determined as the extremum of all extrema. This method has been applied to a rotor-stator stage similar to NASA Stage 35. The study has two parts: a preliminary study where a limited number of design variables were used to give an understanding of the important design variables for subsequent use, and a comprehensive application of the methodology where a larger, more complete set of design variables are used. The extended methodology also attempts to minimize the acoustic fluctuations at the rotor-stator interface by considering a rotor-wake influence coefficient (RWIC). Results presented include performance map calculations at design and off-design speed along with a detailed visualization of the flow field at design and off-design conditions. The present methodology provides a way to systematically screening through the plethora of design variables. By selecting the most influential design parameters and by optimizing the blade leading edge and trailing edge mean camber line angles, phenomenon s such as tip blockages, blade-to-blade shock structures and other loss mechanisms can be weakened or alleviated. It is found that these changes to the configuration can have a beneficial effect on total pressure ratio and stage adiabatic efficiency, thereby improving the performance of the axial compression system. Aeroacoustic benefits were found by minimizing the noise generating mechanisms associated with rotor wake-stator interactions. The new method presented is reliable, low time cost, and easily applicable to industry daily design optimization of turbomachinery blades.

Metal mesh foil bearings (MMFBs) are a promising low cost gas bearing technology for support of high speed oil-free microturbomachinery. Elimination of complex oil lubrication and sealing system by installing MMFBs in oil free rotating machinery offer distinctive advantages such as reduced system overall weight, enhanced reliability at high rotational speeds and extreme temperatures, and extended maintenance intervals compared to conventional turbo machines. MMFBs for oil-free turbomachinery must demonstrate adequate load capacity, reliable rotordynamic performance, and low frictional losses in a high temperature environment. The thesis presents the measurements of MMFB break-away torque, rotor lift off and touchdown speeds, temperature at increasing static load conditions, and identified stiffness and equivalent viscous damping coefficients. The experiments, conducted in a test rig driven by an automotive turbocharger turbine, demonstrate the airborne operation (hydrodynamic gas film) of the floating test MMFB with little frictional loses at increasing loads. The measured drag torque peaks when the rotor starts and stops, and drops significantly once the bearing is airborne. The estimated rotor speed for lift-off increases linearly with increasing applied loads. During continuous operation, the MMFB temperature measured at one end of the back surface of the top foil increases both with rotor speed and static load. Nonetheless, the temperature rise is only nominal ensuring reliable bearing performance. Application of a sacrificial layer of solid lubricant on the top foil surface aids to reduce the rotor break-away torque. The measurements give confidence on this simple bearing technology for ready application into oil-free turbomachinery. Impact loads delivered (with a soft tip) to the test bearing, while resting on the (stationary) drive shaft, evidence a system with large damping and a structural stiffness that increases with frequency (max. 200 Hz). The system equivalent viscous damping ratio decreases from ~ 0.7 to 0.2 as the frequency increases. In general, the viscous damping in a metal mesh structure is of structural type and inversely proportional to the frequency and amplitude of bearing motion relative to the shaft. Impact load tests, conducted while the shaft rotates at 50 krpm, show that the bearing direct stiffness is lower (~25% at 200 Hz) than the bearing structural stiffness identified from impact load tests without shaft rotation. However, the identified equivalent viscous damping coefficients from tests with and without shaft rotation are nearly identical. The orbits of bearing motion relative to the rotating shaft show subsynchronous motion amplitudes and also backward synchronous whirl. The subsynchronous vibration amplitudes are locked at a frequency, nearly identical to a rotor natural frequency. A backward synchronous whirl occurs while the rotor speed is between any two natural frequencies, arising due to bearing stiffness asymmetry.

Torsional vibration is an oscillatory angular twisting motion in the rotating members of a system. It can be deemed quite dangerous in that it cannot be detected as easily as other forms of vibration, and hence, subsequent failures that it leads to are often abrupt and may cause direct breakage of the shafts of the drive train. The need for sufficient analysis during the design stage of a rotating machine is, thus, well justified in order to avoid expensive modifications during later stages of the manufacturing process. In 1998, a project was initiated by the Turbomachinery Research Consortium (TRC) at Texas A&M University, College Station, TX, to develop a suite of computer codes to model torsional vibration of large drive trains. The author had the privilege of developing some modules in Visual Basic for Applications (VBA-Excel) for this suite of torsional vibration analysis codes, now collectively called XLTRC-Torsion. This treatise parleys the theory behind torsional vibration analysis using both the Transfer Matrix approach and the Finite Element approach, and in particular, validates the results generated by XLTRC-Torsion based on those approaches using experimental data available from tests on a 66,000 HP Air Compressor.

<p>Siemens Industrial Turbomachinery AB (SIT AB) i Finspång är ett företag vars verksamhet är inriktad på tillverkning av gas- och ångturbiner för främst industriella tillämpningsområden. Företaget har cirka 2 100 anställda och är en del av den tyska storkoncernen Siemens AG. Inom SIT AB har det sedan tidigare funnits en delad mening kring vilka orsaker som främst bidrar till förluster inom företagets produktion. I dagsläget genomförs flera olika typer av driftsuppföljningar, ett problem är dock att dessa inte är synkroniserade för att ge en tydlig förlustbild på maskinspecifik nivå. Till följd av detta önskar nu produktionsansvariga på SIT AB undersöka möjligheten att mäta utrustningseffektiviteten hos sina maskinresurser genom införande av mätetalet Overall Equipment Effectiveness (OEE). Genom ett pilotprojekt ska en metod för mätning av OEE på SIT AB utvecklas, denna ska sedan implementeras och testas på två av företagets fleroperationsmaskiner. Pilotprojektet genomförs i form av ett examensarbete, arbetet ska ligga till grund för rekommendationer gällande hur mätresultaten ska användas samt hur SIT AB ska gå tillväga för att kunna genomföra OEE-mätningar i större skala.</p><p>OEE avser mätning av total utrustningseffektivitet genom ett enda mätetal. Syftet med beräkningen är att åskådliggöra omfattningen av de sex stora produktionsförluster som definieras inom ramen för Total Productive Maintenance. Efter förlustanalys kan välriktade förbättringsåtgärder vidtas med avsikt att öka utrustningseffektiviteten hos den studerade resursen.</p><p>Inom denna undersökning konstateras att OEE är ett mätetal som främst är framtaget för applikation i processliknande industrier. Eftersom SIT AB bedriver tillverkning i en huvudsakligen funktionell verkstadsmiljö krävs viss anpassning för att öka mätetalets tillämpbarhet på företaget. En sådan anpassning får även stöd i litteraturen där det klargörs att det är viktigare att åstadkomma en mätning som kan ligga till grund för förbättringsarbete än att strikt följa grunddefinitionen av OEE. Som stöd för metodanpassningen genomfördes en fallstudie på Kongsberg Terotech AS (KTT), ett av nordens ledande företag inom branschen för underhåll av verktygsmaskiner. KTT har stor erfarenhet inom OEE-mätning genom arbete som rådgivare på uppskattningsvis 15-20 olika företag där verksamhetsområdena sträcker sig från enstyckstillverkning till processindustri och från skärande bearbetning till livsmedelindustri.</p><p>Den metod som utvecklats för mätning av OEE på SIT AB är helt baserad på storheten tid. Mätningen sker genom tidsregistrering inom ett diskret antal fördefinierade förlustkategorier, framtagna specifikt för de studerade maskinerna. Genom utvecklandet av en specialdesignad blankett kan datainsamlingen skötas av maskinernas operatörer under pågående ordinarie arbete. Mätningarnas manuella utförande utgör ett hinder för exakt stopptidsmätning, konceptet kan dock införas med kort varsel och utan krav på dyra investeringar i avancerad mätutrustning.</p><p>På inrådan från KTT genomfördes OEE-mätning under en period om fyra veckor i respektive maskin. Förlustdata kunde insamlas från 95 av 96 möjliga skift och dataunderlaget omfattar 564 respektive 576 planerade produktionstimmar i vardera resurs. Trots att de båda fleroperationsmaskinerna i princip är identiska till utförandet uppvisades förlustbilder som i jämförelse är relativt olika. Av detta dras slutsatsen att maskinerna bör behandlas individuellt vid vidtagandet av eventuella förbättringsåtgärder.</p><p>OEE-mätning är något som enbart ska utföras i syfte att underlätta och motivera kontinuerligt förbättringsarbete kopplat till företagets tillverkningsprocesser. Den framtagna mätmetoden kan hjälpa SIT AB att värdera förbättringspotentialen hos den studerade produktionsutrustningen, insamlad data kan även användas för att prioritera hur förbättringsinsatserna ska fokuseras. Huvuddragen i metoden kan även användas för mätning i stor skala, förlustkategorier bör dock väljas utgående från den maskin där mätningarna ska introduceras. En tydlig nackdel är att metoden i nuvarande utförande inte säkerställer god kvalitet i insamlad data, detta kan innebära viss risk för att beslut fattas på felaktiga grunder. Metoden kan vara lämplig att använda som introduktion till OEE-mätning eller i det fall att företaget vill undvika mer omfattande investeringar kopplat till mätningarna. Om SIT AB i framtiden vill satsa på OEE-mätning rekommenderas att datainsamlingen automatiseras.</p><p>Det förbättringsarbete som ska följa av genomförda OEE-mätningar bör skötas av förbättringsgrupper tillsatta för ändamålet. Förbättringsgrupperna innehåller med fördel personal med olika kunskapsområden. En tvärfunktionell sammansättning bör innebära att förbättringsarbetet kan skötas på ett mer mångsidigt sätt än vid behandling av enskilda personalgrupper. Den viktigaste förutsättningen för ett lyckat förbättringsarbete är att alla beslut kan baseras på fakta från verkligheten, mätningar som exempelvis OEE utgör konkreta verktyg för att åstadkomma denna situation. För att kunna styra och förbättra centrala produktionsprocesser måste dessa ständigt utvärderas. I detta sammanhang kan införandet av OEE-mätning komma att spela en central roll för verksamheten på SIT AB.</p> / <p>Siemens Industrial Turbomachinery AB (SIT AB) in Finspong is a company dedicated to the production of gas- and steam turbines mainly for industrial applications. The company has around 2 100 employees and is a part of Siemens AG based in Germany. There have previously been different opinions regarding what the largest causes of losses within the company’s production are. Today a number of different ways to follow up on the production is used, a problem with these are however that they are not synchronized to give a clear view of the losses on any specific machine. As a result the production managers at SIT AB now want to look into the possibility of measuring the machines´ effectiveness by introduction of the technique Overall Equipment Effectiveness (OEE). A method for measuring OEE at SIT AB will be developed through a pilot study, this will then be implemented and tested on two of the company’s multifunctional machines. The pilot study is to be performed in the form of a master’s thesis, the paper will be the basis for recommendations regarding how the results of the measurements shall be used and how SIT AB should go about making the measurements usable on a grander scale.</p><p>OEE is used to show a resource’s total effectiveness with a single parameter. The calculations are aimed at illustrating to which extent the six big losses defined within Total Productive Maintenance affect the production. After the losses have been analysed improvement measures can be taken in order to increase the previously measured resource effectiveness.</p><p>Within this thesis it is concluded that OEE is developed mainly for use in mass-producing industries. Since SIT AB conducts production with similarities closer to a work-shop some adjustments have to be made in order to make OEE more applicable in the company. Such adjustments are supported by the literature where it is stated that it is more important to achieve a measurement which can be used as a basis for improvement rather then to strictly follow the original definition of OEE. As a support for the work with these adjustments a case study was conducted at Kongsberg Terotech AS (KTT), one of the leading companies regarding maintenance of tooling machines in the Nordic countries. KTT has gained a lot of experience when it comes to measuring OEE since they have worked as counsellors at approximately 15-20 different companies ranging from production of single units to mass-production and from metalwork to the food industry.</p><p>The method developed for the measurement of OEE at SIT AB is completely based on the entity time. The information is gathered by means of time being registered within a discrete number of predefined loss-categories designed specifically for the studied resources. Since a specially designed form is used the gathering of information can be performed by the operators during regular work. Exact registration of losses is hindered by the measurements being performed manually, however this allows the concept to be introduced with short notice and without the need of expensive investments regarding advanced equipment.</p><p>For manual data collecting KTT advised that the measurements should be performed for a period of four weeks in each machine. Data containing the losses could be gathered from 95 out of 96 shifts, which means observation of 564 and 576 planned production hours respectively in each machine. Despite the identical features of the multifunctional machines they presented different losses. This leads to the conclusion being drawn that all machines must be treated individually when it comes to deciding improvement measures.</p><p>Measuring OEE should only be carried out when the purpose is to create a basis for continuous improvement of the company’s production processes. The developed measuring technique can aid SIT AB in evaluating the potential for improvement of the studied equipment, the data can also be used to prioritize where improvement measures should be taken first. The main part of the technique can be used for measurements on a grander scale, the loss categories should however be chosen in accordance with the specific machine being studied. A clear down side is that the method in its current state does not secure good quality data, this can potentially mean that decisions are made based on false information. The method is suited for an introduction to OEE or if a company wants to avoid extensive investments. For the best possible result an automatic data collecting system is advised.</p><p>Improvement activities based on the OEE measurements should be carried out in groups appointed for the task. These groups should consist of staff with different areas of expertise, a cross functional composition will hopefully mean that the work with improvements can be undertaken in a versatile manner. The most important prerequisite for successful work with improvements is that all decisions are based on facts, measuring OEE can be used as a tool to present the reality. In order to be able to control and improve important production processes these must be constantly evaluated. In this context the introduction of OEE measurements can play an important role for the production system at SIT AB.</p>

Siemens Industrial Turbomachinery AB (SIT AB) i Finspång är ett företag vars verksamhet är inriktad på tillverkning av gas- och ångturbiner för främst industriella tillämpningsområden. Företaget har cirka 2 100 anställda och är en del av den tyska storkoncernen Siemens AG. Inom SIT AB har det sedan tidigare funnits en delad mening kring vilka orsaker som främst bidrar till förluster inom företagets produktion. I dagsläget genomförs flera olika typer av driftsuppföljningar, ett problem är dock att dessa inte är synkroniserade för att ge en tydlig förlustbild på maskinspecifik nivå. Till följd av detta önskar nu produktionsansvariga på SIT AB undersöka möjligheten att mäta utrustningseffektiviteten hos sina maskinresurser genom införande av mätetalet Overall Equipment Effectiveness (OEE). Genom ett pilotprojekt ska en metod för mätning av OEE på SIT AB utvecklas, denna ska sedan implementeras och testas på två av företagets fleroperationsmaskiner. Pilotprojektet genomförs i form av ett examensarbete, arbetet ska ligga till grund för rekommendationer gällande hur mätresultaten ska användas samt hur SIT AB ska gå tillväga för att kunna genomföra OEE-mätningar i större skala. OEE avser mätning av total utrustningseffektivitet genom ett enda mätetal. Syftet med beräkningen är att åskådliggöra omfattningen av de sex stora produktionsförluster som definieras inom ramen för Total Productive Maintenance. Efter förlustanalys kan välriktade förbättringsåtgärder vidtas med avsikt att öka utrustningseffektiviteten hos den studerade resursen. Inom denna undersökning konstateras att OEE är ett mätetal som främst är framtaget för applikation i processliknande industrier. Eftersom SIT AB bedriver tillverkning i en huvudsakligen funktionell verkstadsmiljö krävs viss anpassning för att öka mätetalets tillämpbarhet på företaget. En sådan anpassning får även stöd i litteraturen där det klargörs att det är viktigare att åstadkomma en mätning som kan ligga till grund för förbättringsarbete än att strikt följa grunddefinitionen av OEE. Som stöd för metodanpassningen genomfördes en fallstudie på Kongsberg Terotech AS (KTT), ett av nordens ledande företag inom branschen för underhåll av verktygsmaskiner. KTT har stor erfarenhet inom OEE-mätning genom arbete som rådgivare på uppskattningsvis 15-20 olika företag där verksamhetsområdena sträcker sig från enstyckstillverkning till processindustri och från skärande bearbetning till livsmedelindustri. Den metod som utvecklats för mätning av OEE på SIT AB är helt baserad på storheten tid. Mätningen sker genom tidsregistrering inom ett diskret antal fördefinierade förlustkategorier, framtagna specifikt för de studerade maskinerna. Genom utvecklandet av en specialdesignad blankett kan datainsamlingen skötas av maskinernas operatörer under pågående ordinarie arbete. Mätningarnas manuella utförande utgör ett hinder för exakt stopptidsmätning, konceptet kan dock införas med kort varsel och utan krav på dyra investeringar i avancerad mätutrustning. På inrådan från KTT genomfördes OEE-mätning under en period om fyra veckor i respektive maskin. Förlustdata kunde insamlas från 95 av 96 möjliga skift och dataunderlaget omfattar 564 respektive 576 planerade produktionstimmar i vardera resurs. Trots att de båda fleroperationsmaskinerna i princip är identiska till utförandet uppvisades förlustbilder som i jämförelse är relativt olika. Av detta dras slutsatsen att maskinerna bör behandlas individuellt vid vidtagandet av eventuella förbättringsåtgärder. OEE-mätning är något som enbart ska utföras i syfte att underlätta och motivera kontinuerligt förbättringsarbete kopplat till företagets tillverkningsprocesser. Den framtagna mätmetoden kan hjälpa SIT AB att värdera förbättringspotentialen hos den studerade produktionsutrustningen, insamlad data kan även användas för att prioritera hur förbättringsinsatserna ska fokuseras. Huvuddragen i metoden kan även användas för mätning i stor skala, förlustkategorier bör dock väljas utgående från den maskin där mätningarna ska introduceras. En tydlig nackdel är att metoden i nuvarande utförande inte säkerställer god kvalitet i insamlad data, detta kan innebära viss risk för att beslut fattas på felaktiga grunder. Metoden kan vara lämplig att använda som introduktion till OEE-mätning eller i det fall att företaget vill undvika mer omfattande investeringar kopplat till mätningarna. Om SIT AB i framtiden vill satsa på OEE-mätning rekommenderas att datainsamlingen automatiseras. Det förbättringsarbete som ska följa av genomförda OEE-mätningar bör skötas av förbättringsgrupper tillsatta för ändamålet. Förbättringsgrupperna innehåller med fördel personal med olika kunskapsområden. En tvärfunktionell sammansättning bör innebära att förbättringsarbetet kan skötas på ett mer mångsidigt sätt än vid behandling av enskilda personalgrupper. Den viktigaste förutsättningen för ett lyckat förbättringsarbete är att alla beslut kan baseras på fakta från verkligheten, mätningar som exempelvis OEE utgör konkreta verktyg för att åstadkomma denna situation. För att kunna styra och förbättra centrala produktionsprocesser måste dessa ständigt utvärderas. I detta sammanhang kan införandet av OEE-mätning komma att spela en central roll för verksamheten på SIT AB. / Siemens Industrial Turbomachinery AB (SIT AB) in Finspong is a company dedicated to the production of gas- and steam turbines mainly for industrial applications. The company has around 2 100 employees and is a part of Siemens AG based in Germany. There have previously been different opinions regarding what the largest causes of losses within the company’s production are. Today a number of different ways to follow up on the production is used, a problem with these are however that they are not synchronized to give a clear view of the losses on any specific machine. As a result the production managers at SIT AB now want to look into the possibility of measuring the machines´ effectiveness by introduction of the technique Overall Equipment Effectiveness (OEE). A method for measuring OEE at SIT AB will be developed through a pilot study, this will then be implemented and tested on two of the company’s multifunctional machines. The pilot study is to be performed in the form of a master’s thesis, the paper will be the basis for recommendations regarding how the results of the measurements shall be used and how SIT AB should go about making the measurements usable on a grander scale. OEE is used to show a resource’s total effectiveness with a single parameter. The calculations are aimed at illustrating to which extent the six big losses defined within Total Productive Maintenance affect the production. After the losses have been analysed improvement measures can be taken in order to increase the previously measured resource effectiveness. Within this thesis it is concluded that OEE is developed mainly for use in mass-producing industries. Since SIT AB conducts production with similarities closer to a work-shop some adjustments have to be made in order to make OEE more applicable in the company. Such adjustments are supported by the literature where it is stated that it is more important to achieve a measurement which can be used as a basis for improvement rather then to strictly follow the original definition of OEE. As a support for the work with these adjustments a case study was conducted at Kongsberg Terotech AS (KTT), one of the leading companies regarding maintenance of tooling machines in the Nordic countries. KTT has gained a lot of experience when it comes to measuring OEE since they have worked as counsellors at approximately 15-20 different companies ranging from production of single units to mass-production and from metalwork to the food industry. The method developed for the measurement of OEE at SIT AB is completely based on the entity time. The information is gathered by means of time being registered within a discrete number of predefined loss-categories designed specifically for the studied resources. Since a specially designed form is used the gathering of information can be performed by the operators during regular work. Exact registration of losses is hindered by the measurements being performed manually, however this allows the concept to be introduced with short notice and without the need of expensive investments regarding advanced equipment. For manual data collecting KTT advised that the measurements should be performed for a period of four weeks in each machine. Data containing the losses could be gathered from 95 out of 96 shifts, which means observation of 564 and 576 planned production hours respectively in each machine. Despite the identical features of the multifunctional machines they presented different losses. This leads to the conclusion being drawn that all machines must be treated individually when it comes to deciding improvement measures. Measuring OEE should only be carried out when the purpose is to create a basis for continuous improvement of the company’s production processes. The developed measuring technique can aid SIT AB in evaluating the potential for improvement of the studied equipment, the data can also be used to prioritize where improvement measures should be taken first. The main part of the technique can be used for measurements on a grander scale, the loss categories should however be chosen in accordance with the specific machine being studied. A clear down side is that the method in its current state does not secure good quality data, this can potentially mean that decisions are made based on false information. The method is suited for an introduction to OEE or if a company wants to avoid extensive investments. For the best possible result an automatic data collecting system is advised. Improvement activities based on the OEE measurements should be carried out in groups appointed for the task. These groups should consist of staff with different areas of expertise, a cross functional composition will hopefully mean that the work with improvements can be undertaken in a versatile manner. The most important prerequisite for successful work with improvements is that all decisions are based on facts, measuring OEE can be used as a tool to present the reality. In order to be able to control and improve important production processes these must be constantly evaluated. In this context the introduction of OEE measurements can play an important role for the production system at SIT AB.

The steady flow aerodynamics of a cascade of compressor airfoils is computed using a two-dimensional thin layer Navier-Stokes flow solver. The Dhawan and Narasimha transition model and Mayle‟s transition length model were implemented in this flow solver so that transition from laminar to turbulent flow could be included in the computations. A method to speed up the convergence of the fully turbulent calculations has been introduced. In addition, the effect of turbulence production formulations and including streamline curvature correction in the Spalart-Allmaras turbulence model on the transition calculations is studied. These transitional calculations are correlated with the low and high incidence angle experimental data from the NASA-GRC Transonic Flutter Cascade. Including the transitional flow showed a trendwise improvement in the correlation of the computational predictions with the pressure distribution experimental data at the high incidence angle condition where a large separation bubble existed in the leading edge region of the suction surface.

Neste trabalho é realizada a concepção, projeto, construção e ensaio de turbinas de múltiplos discos para a verificação dos principais parâmetros e metodologias utilizadas para o projeto e análise do equipamento, além de estudar formas de otimização do equipamento. Assim, uma turbina de múltiplos discos é construída e testada com diferentes configurações de rotores, em uma bancada experimental construída e dimensionada especialmente para esse fim, além da implementação dos métodos analíticos pesquisados no software Engineering Equation Solver (EES). Assim, uma comparação entre os resultados experimentais obtidos por Rice e os modelos de analíticos disponíveis, mostra que o modelo do fator de atrito (FA) é o que melhor representa a operação do equipamento, além de ser o mais versátil dos métodos testados, permitindo que a turbina seja dimensionada e otimizada para várias configurações de construção. Já os resultados experimentais obtidos com um dos protótipos de turbina construído e operado com ar comprimido, mostram que, com modificações simples da geometria, configuração e acabamento superficial dos discos que compõem o rotor, é possível aumentar a eficiência isentrópica em até 35% em relação a turbina padrão montada com a configuração padrão de rotor (discos lisos), sem acarretar prejuízo em alguns dos principais benefícios da utilização deste tipo de equipamento. Os resultados experimentais obtidos mostram também que a eficiência diminui significativamente com o aumento da folga entre o raio externo do rotor e a parte interna da carcaça. / This work is performed conception, design, construction and testing of multiple-disks turbines (MDTs) for the verification of key parameters and methodologies used for the design and analysis of machine as well as consider ways to equipment optimization. Thus, a multiple-disk turbine is constructed and tested with different impeller configurations, in a test rig especially constructed and dimensioned for this purpose, besides the implementation of the analytical methods in software Engineering Equation Solver (ESS). Thus, a comparison between the experimental results obtained by Rice and analytical models available, shows that the friction factor model (FF) is what best represents the operation of the equipment, and is the most versatile of the tested methods, allowing the turbine is sized and optimized for various building configurations. Since the experimental results obtained with one of the turbine prototypes built and operated with compressed air, show that with simple modifications of geometry, configuration and surface finish of the disks that make up the rotor, it is possible to increase the isentropic efficiency by up to 35% compared the standard turbine rotor mounted with the default configuration (flat disks), without causing damage in some of the major benefits of using this type of equipment. The experimental results also show that efficiency decreases significantly with increasing clearance between the outer radius of the rotor and the internal part of the housing.

Les turbines à gaz modernes deviennent de plus en plus compactes, ce qui augmente les interactions entre leurs différents composants. Les interactions chambre de combustion-turbine sont particulièrement critiques car elles peuvent changer le champ aérothermique dans la turbine et réduire la durée de vie du moteur. Aujourd’hui, ces deux composants sont traités de façon indépendante, ce qui ne permet pas de prendre en compte leurs interactions. Cette thèse propose une approche couplée, basée sur les Simulations aux Grandes Échelles (SGE), une technique qui permet de prendre en compte toutes les interactions chambre de combustion-turbine. Dans la première partie de cette thèse, une méthode, compatible avec le code SGE AVBP, est proposée pour traiter les configurations rotor/stator de manière rigoureuse. Une série de cas test académiques vient prouver que l’interface respecte les propriétés des schémas numériques du code. Cette étude est suivie par une validation de l’approche dans le cas d'une turbine haute-pression mono-étage. Les résultats sont comparés avec des mesures expérimentales et l’influence des différents paramètres et modèles est établi. La deuxième partie de cette travail est dédiée à la prédiction des interactions chambre de combustion-turbine en utilisant les méthodes précédemment décrites et validées. Le premier type d’interaction étudié est la génération du bruit de combustion indirect dans une turbine haute pression. Ce bruit est créé lorsque des hétérogénéités de température, générées dans la chambre de combustion, sont accélérées dans la turbine. Pour simplifier les calculs, les hétérogénéités sont modélisées par des fluctuations de température sinusoïdales, injectées dans la turbine par les conditions limites. Les mécanismes de génération de bruit sont mis en évidence et le bruit de combustion indirect est mesuré et comparé avec une théorie analytique et des prédictions 2D. La deuxième application est un calcul couplé chambre de combustion-turbine qui analyse les interactions entre ces deux composants d’un point de vue aérothermique. Les caractéristiques instationnaires de l’écoulement à l’entrée de la turbine et la migration des hétérogénéités de température dans la turbine sont étudiées. Un calcul de la turbine seule est aussi effectué pour comparaison avec le calcul couplé. / Modern gas turbines are characterized by compact designs that enhance the interactions between its different components. Combustion chamber-turbine interactions, in particular, are critical as they may alter the aerothermal flow field of the turbine which can drastically impact the engine life duration. Current state-of-the-art treats these two components in a decoupled way and does not take into account their interactions. This dissertation proposes a coupled approach based on the high-fidelity Large Eddy Simulation (LES) formalism that can take into account all the potential paths of interactions between components. In the first part of this work, an overset grid method is proposed to treat rotor/stator configurations in a rigorous fashion that is compatible with the LES solver AVBP. This interface treatment is shown not to impact the characteristics of the numerical schemes on a series of academic test cases of varying complexity. The approach is then validated on a realistic high-pressure turbine stage. The results are compared against experimental measurements and the influence of different modeling and simulation parameters is evaluated. The second part of this work is dedicated to the prediction of combustion chamber-turbine interactions using the developed methodologies. The first type of interactions evaluated is the indirect combustion noise generation across a high-pressure turbine stage. This noise arises when combustor-generated temperature heterogeneities are accelerated in the turbine. To simplify the simulations the heterogeneities are modeled by sinusoidal temperature fluctuations injected in the turbine through the boundary conditions. The noise generation mechanisms are revealed by such LES and the indirect combustion noise is measured and compared to an analytical theory and 2D predictions. The second application is a fully-coupled combustor-turbine simulation that investigates the interactions between the two components from an aerothermal point of view. The rich flow characteristics at the turbine inlet, issued by the unsteady combustion in the chamber, are analyzed along with the migration of the temperature heterogeneities. A standalone turbine simulation serves as a benchmark to compare the impact of the fully coupled approach.

Dans un contexte d'amélioration des moteurs aéronautiques en termes de consommation et de pollution, les simulations numériques apparaissent comme un outil intéressant pour mieux comprendre et modéliser les phénomènes turbulents qui se produisent dans les turbomachines. La simulation aux grandes échelles (SGE) d’un étage de turbomachine à des conditions réalistes (nombre de Mach, nombre de Reynolds…) reste toutefois hors de portée dans le cadre industriel. La méthode chorochronique, aujourd’hui largement utilisée pour les calculs URANS, permet de réduire le coût des simulations numériques, mais elle implique de stocker le signal aux frontières du domaine pendant une période complète de l’écoulement. Le stockage direct de l’information étant exclu étant donné la taille des maillages et les pas de temps mis en jeu, la solution la plus courante actuellement est de décomposer le signal sous la forme de séries de Fourier. Cette solution ne retient du signal qu’une fréquence fondamentale (la fréquence de passage de la roue opposée) et un nombre limité d’harmoniques. Dans le cadre d’une SGE, elle implique donc une grande perte d’énergie, et le filtrage des phénomènes décorrélés de la vitesse de rotation comme par exemple un lâcher tourbillonnaire. Le remplacement de la décomposition en séries de Fourier par une décomposition aux valeurs propres (POD pour Proper Orthogonal Decomposition) permet de stocker le signal aux interfaces sans faire d’hypothèse sur les fréquences contenues dans le signal et donc de réduire la perte d’énergie liée à l’utilisation d’un modèle réduit. La compression s’effectue en supprimant les plus petites valeurs singulières et les vecteurs associés. Cette nouvelle méthode est validée sur la simulation URANS d'étages de turbomachines et comparée aux conditions classiques utilisant les séries de Fourier et à des calculs de références contenant plusieurs aubes par roue. Elle est ensuite appliquée à la simulation aux grandes échelles de l'écoulement d'un cylindre. Les erreurs causées par l'hypothèse chorochronique et par la compression sont séparées et on montre que l'utilisation de la POD permet de réduire de moitié le filtrage des fluctuations de vitesses par rapport aux séries de Fourier pour un même taux de compression. Enfin, la simulation aux grandes échelles d'un étage de turbomachine avec des conditions chorochroniques POD est réalisée afin de valider la méthode dans le cadre d'une configuration industrielle. / The more and more restrictive standards in terms of fuel consumption and pollution for aircraft engines lead to a constant improvement of their design. Numerical simulations appear as an interesting tool for a better understanding and modeling of the turbulent phenomena which occur in turbomachinery. The large-eddy simulation (LES) of a turbomachinery stage at realistic conditions (Mach number, Reynolds number...) remains out of reach for industrial congurations. The phase-lagged method, widely used for unsteady Reynolds-averaged Navier--Stockes (URANS) calculations, is a good candidate to reduce the computational cost. However, it needs to store the signal at all the boundaries over a full passage of the opposite blade. A direct storage of the information being excluded given the size of the mesh grid and timesteps involved, the most used solution currently is to decompose the signal into Fourier series. This solution retains the fundamental frequency of the signal (the opposite blade passage frequency) and a limited number of harmonics. In the frame of a LES, as the spectra are broadband, it implies a loss of energy. Replacing the Fourier series decomposition by a proper orthogonal decomposition (POD) allows the storage of the signal at the interfaces without making any assumptions on the frequency content of the signal, and helps to reduce the loss of energy caused by the phase lagged method. The compression is done by removing the smallest singular values and the associated vectors. This new method is first validated on the URANS simulations of turbomachinery stages and compared with Fourier series-based conditions and references calculations with multiple blades per row. It is then applied to the large eddy simulation of the flow around a cylinder. The error caused by the phase-lagged assumption and compression are separated and it is showed that the use of the POD allows to halve the filtering of the velocity fluctuations with respect to the Fourier series, for a given compression rate. Finally, the large eddy simulation of a compressor stage with POD phase-lagged conditions is carried out to validate the method for realistic turbomachinery configurations.

La prise en compte de la transition laminaire-turbulent dans les codes Navier-Stokes demeure problématique d’un point de vue numérique dès lors qu’on s’intéresse à des géométries complexes tridimensionnelles tel qu’un étage de turbomachine. Le modèle à équations de transport Re se propose de résoudre ces difficultés et d’ouvrir la voie à la modélisation automatique du phénomène pour des simulations RANS. Le travail exposé dans ce mémoire de thèse a consisté à développer dans le code elsA le modèle de transition Re et à évaluer l’aptitude de ce modèle à capturer avec précision le phénomène de la transition laminaire-turbulent dans le cadre de simulations RANS en turbomachine. Après une étude bibliographique, l’implémentation du modèle dans le code elsA est décrite ainsi que des premières simulations validant les développements réalisés. Par la suite, des cas documentés relatifs à des applications en aérothermique sont traités. Les prévisions par CFD des flux de chaleur à la paroi sont en bon accord avec l’expérience, démontrant ainsi la capacité du modèle à capturer avec précision la nature de la couche limite. Dans une dernière partie, le modèle est appliqué à la prévision de la transition par bulbe de décollement sur des aubages de turbine basse pression. Les résultats obtenus indiquent que le modèle doit être amélioré afin de modéliser correctement le phénomène de transition par bulbe de décollement. Ces travaux ont permis de valider l’utilisation du modèle de transition Re dans le code elsA pour une large gamme d’applications en turbomachine, et laissent entrevoir la perspective d’utiliser ce modèle. / The modelisation of laminar to turbulent transition is still difficult in RANS computations while dealing with three dimensional computational domains like turbomachinery domains. The laminar to turbulent transition model Re has been proposed to solve these issues and permit the automatic modeling of laminar to turbulent transition in RANS codes. The Re model has been introduced into the code elsA and evaluated thanks to several computations relative to turbomachinery. After a bibliographical study, the implementation of the model into the code elsA and the inital results are described in this document. In a third part, aerothermal issues in turbomachinery are investigated. The estimations of the heat fluxes by CFD are in good agreement with the experimental data which demonstrate the capability of the model to capture laminar and turbulent regions. In a last part the phenomenon of separation induced transition occuring on low pressure turbine blade is studied. The results obtained while employing the Re model show that the model need to be refined for these applications. The studied performed have permited the validation the use of the laminar to turbulent transition model Re with the code elsA for very different applications in turbomachinery.