This thesis is concerned with the topic of Pumps with crew centrifugal impeller. Thanks to the benefits such as free passage and efficiency there are many practical applications of these products. Despite this fact there is only few manufacturers dealing with them what results in lack of research and available information in the area. In order to fill the gap, this thesis aims to propose hydraulic of screw centrifugal impeller to the specified parameters. The impeller with a single moving blade will be designed for pumping heavily polluted water and hardly pumpable liquids. Blade will be balanced together with the rotor, while the emphasis will be placed on the highest free passage of impeller. The theoretical part of the thesis summarizes literature on the subject, practical part deals with the calculations and adjustments pointing to a concrete proposal. Parameters of designed hydraulics were verified using stationary calculations using MRF model in FLUENT. As a results, two possible solutions are offered.

During combustion of biomass, particulate matter is emitted, which has severe health impacts on humans. The company ITK Envifront has developed a scrubber technology that cleans the flue gas while also recovering the flue gas energy, increasing the efficiency of the combustion plant. In this thesis, a simulation model was built in MATLAB according to the Finite Element Method. Validation of the model against 3 different facilities showed reasonable accuracy with a tendency to overestimate the scrubber heat recovery and a mean prediction deviation of approximately 7 %. The model was then used to make suggestions for process optimization. An increase of funnel height, and number of spray nozzles could increase the scrubbers heat recovery with up to 7 % and 8 %, respectively. Addition of moisture to the flue gas through evaporation of water droplets had the potential to increase scrubber efficiency with 10 %, and usage of the highest setting of the adjustable nozzle bank showed the potential to increase the efficiency with up to 5 % compared to the mid-setting. Furthermore, the process parameters of a scrubber with optimized running conditions, was compared to a scrubber with the current running conditions, through running of the developed model. The optimized running conditions showed an increase in scrubber efficiency with up to 14 %, resulting in an increase in scrubber heat recovery of approx. 90 kW at a boiler load of 3 MW. As a final conclusion, the developed model shows great potential to be used to as a toolbox to further investigate and optimize the scrubber design and operation. As a future work, it would be interesting to further model its performance regarding particle removal.

<p>Кавитација један од главних проблема који угрожавају рад центрифугалних пумпи, пре свега због последица које је прате: ерозија материјала, нестабилан рад, бука, вибрације итд. Познато је да кавитацијски индуковане вибрације кућишта пумпи показују карактеристичан тренд са повећањем интензитета кавитације. Експериментална истраживања урађена у оквиру дисертације, показала су да је у реалним радним условима могуће из мерног сигнала виб-рација издвојити оне параметре који указују на развој кавитације у центри-фугалним пумпама. Посебно добре резултате дала је нормирана укупна ефективна вибрацијска брзина, која је у оквиру дисертације предложена као параметар за детекцију кавитације у центрифугалним пумпама.</p> / <p>Kavitacija jedan od glavnih problema koji ugrožavaju rad centrifugalnih pumpi, pre svega zbog posledica koje je prate: erozija materijala, nestabilan rad, buka, vibracije itd. Poznato je da kavitacijski indukovane vibracije kućišta pumpi pokazuju karakterističan trend sa povećanjem intenziteta kavitacije. Eksperimentalna istraživanja urađena u okviru disertacije, pokazala su da je u realnim radnim uslovima moguće iz mernog signala vib-racija izdvojiti one parametre koji ukazuju na razvoj kavitacije u centri-fugalnim pumpama. Posebno dobre rezultate dala je normirana ukupna efektivna vibracijska brzina, koja je u okviru disertacije predložena kao parametar za detekciju kavitacije u centrifugalnim pumpama.</p> / <p>Cavitation is one of the main problems which could jeopardize the operation of centrifugal pumps, primarily due to its consequences: material erosion, unsteady operation, noise, vibrations, etc. It is known that cavitation induced vibrations of the pump casing shows characteristic trend with increasing cavitation intensity. Field measurements and carried out within the thesis, showed that it is possible to extract from the measured vibration signal specific parameters which points to cavitation inception and intensification in pumps. Particularly good results were obtained using normalized effective vibration velocity, which is proposed within the thesis as the parameter for the cavitation detection in centrifugal pumps.</p>

The objective of this research is to investigate the effects of tip clearance on the stage and component performance in a high-speed centrifugal compressor. The experimental data were compared against results from a numerical model to assess the ability of the numerical simulation to predict the effects of tip clearance. Experimental data were collected at Purdue University on the Single Stage Centrifugal Compressor (SSCC), a high-speed, high-pressure ratio test compressor sponsored by Honeywell Aerospace. Numerical simulations were completed using the ANSYS CFX software suite and part of the research computing clusters located at Purdue University.<div><br></div><div>Two tip clearances were tested, the nominal tip clearance and a tip clearance that is 66% larger than the nominal clearance, at speeds from 60% to 100% corrected speed. To compare data points with different tip clearances, various parameters were evaluated, and one was chosen. The value of TPR/inlet corrected mass flow rate best represented similar loading conditions, and thus similar incidences, for each tip clearance and was chosen as the best method for comparing similar data points taken with different clearances. Stage and component performance were focused on the sensitivity of each performance parameter to the changing of the tip clearance. The stage total pressure ratio and stage efficiency showed moderate sensitivity while the stage work factor showed much lower sensitivity. The impeller is more sensitive to changing tip clearances than the stage is, showing greater changes when comparing data from each tip clearance. The diffuser was on the same order of sensitivity as the impeller, with marginally higher sensitivities for some parameters. It was found that by the typical performance metrics, the diffuser performs worse at the nominal clearance than at the larger clearance. Upon further investigation though, the impeller is providing a higher static pressure and therefore, more diffusion, at the nominal clearance so the diffuser must perform less diffusion during nominal clearance operation.<br></div><div><br></div><div>To assess the validity of a prediction of the performance and sensitivity of the stage and components to the tip clearance, a numerical model was developed and validated. The numerical model was able to reasonably predict the stage performance with better comparisons of performance in the impeller and worse in the diffuser. The instrumentation in the experiment was replicated in the software to calculate performance the same way it is calculated experimentally so that the results would be comparable. While the performance of the stage and components was lacking in some areas, the trends predicted were similar to those calculated from the experimental data. As with the performance, the trends in the impeller matched very well between the experiment and the numerical simulation. The trends in stage and diffuser performance were predicted more accurately than the stage and diffuser performance maps and were able to capture the magnitude of the change in performance caused by changing the tip clearance. <br></div>

[pt] Grande parte dos sistemas de bombeamento existentes em refinarias é do tipo centrífuga com rotor em balanço. Alguns desses sistemas, que foram fabricadas antes da década de 80, ainda estão sendo usadas em refinarias no Brasil. Tipicamente estes equipamentos possuem rotores muito flexíveis. Isto ocorre devido ao alto valor da razão entre a distância entre mancais e o diâmetro do eixo e também por causa da substituição de gaxetas, que oferecem rigidez, por selos mecânicos. Como consequência, a resposta dinâmica destes equipamentos é sensível à pequenas variações da folga entre os anéis de desgaste. O desgaste devido a erosão e ao contato entre as superfícies aumentam a folga, causando aumento da vibração e redução de eficiência, pois aumenta a vazão através dos anéis. Visando contribuir para a solução destes inconvenientes na operação de bombas centrífugas, o presente trabalho investigou a viabilidade de substituir o anel de desgaste estático por flutuante através de análise rotodinâmica com o auxílio dos softwares ROMAC e XLTRC2. A anel flutuante proporcionaria a redução da erosão e aumento da eficiência de bombeio, proporcionado pela montagem com folga reduzida. Outra vantagem é a redução da resposta ao desbalanceamento causado pelo aumento da rigidez e amortecimento. A desvantagem de usar anel flutuante é que este deve ser projetado para cada condição operacional. / [en] A major pumping systems used in refineries is overhung centrifugal pump. Some of them, which were manufactured before 80 s, are still being used in refineries in Brazil. Usually theses equipments have flexible rotors since the ratio L/D is high and the packing, that offers stiffness, was replaced by mechanical seals in order to get more safety. As consequence, the dynamic response of these pumps is very sensitive to any variation of the wear ring clearance.Weariness due to erosion and surfaces in contact increase the diametral clearance of the wear ring, that increases the vibration and reduces the efficiency of the pump since the flow through the seals rises. So, in order to solve these two concerns (vibration and efficiency) this study investigated the feasibility of replacing the static ring by the floating wear ring through rotordynamic analyses using the following software: ROMAC and XLTRC2. Floating wear ring reduces the erosion and increases the efficiency of the pump since it permits to minimize the radial clearance. The disadvantage of using floating wear ring is that each one has to be designed for a specific operation condition.

Le développement de nouvelles motorisations plus économes en carburant, entraine une augmentation du niveau de vibration. Afin de répondre à cela, Valeo développe un nouveau système : le pendule centrifuge. C’est dans cette phase de développement que s’inscrit ce travail de thèse. L’objectif est de réaliser un outil de pré-dimensionnement permettant de modéliser l’endommagement des guidages d’un pendule centrifuge. Une première étude expérimentale présente la faisabilité du suivi du système mécanique par l’utilisation de l’imagerie dynamique. Des essais de caractérisation matériaux des différents constituants du système viennent ensuite compléter l’étude. Ce travail expérimental réalisé à l’aide d’un tribomètre bi-disque permet d’obtenir les lois de frottements en fonction du taux de glissement ainsi que leur sensibilité à l’état de surface, au traitement thermique et au chargement. Un modèle théorique de détermination des valeurs du glissement est ensuite proposé, permettant de prendre en compte les différentes géométries de pendules. Enfin, les perspectives d’industrialisation sont envisagées en proposant une étude paramétrique sur le système réel en vue de son dimensionnement ainsi qu’une étude d’endurance pour modéliser l’usure du système. / The development of more fuel efficient engines results in an increase in the vibration levels. To solve this, Valeo is developing a new system: the centrifugal pendulum. This PhD research thesis registered as a contribution to the system development phase. The objective is to realize a predimensioning tool in order to model the wear of a centrifugal pendulum. A first experimental study shows the feasibility of monitoring the mechanical system through the use of dynamic imaging. Materials characterization tests of the various system components complete the study. The experimental work carried out using a twin-disc tribometer provides the friction laws versus sliding rate and their sensitivity to surface condition, processing and loading. A theoretical model for determining sliding values is then proposed to take into account the different pendulum geometries. Finally, the perpectives of industrialization are considered with a parametric study on the real system for a sizing purpose and an endurance study to model the wear of the system.

No description available.

The centrifugal casting process is a common method for manufacturing the tubes, etc. Due to its high temperature and invisible mold, it is really difficult to know the mechanism of molten steel inside the mold. It is important to know the mechanism of the molten steel inside mold, since it will help the manufacturer to know more accuracy of the flow of the molten steel so that it can work for improving the productivity and quality of the products. Casting funnel design is the designed by Åkers for their funnel which will result in different flow behavior. In thesis work, casting funnel design will be investigated so that it can make sure that the casting funnel design can affect the flow behavior of molten steel or not. Another method of changing the diameter of nozzle was also carried out and investigated with both simulation and experiment to changing flow behavior of molten steel. It will give Åkers alternative method for changing the flow behavior to liquid steel. The mechanism of solidification in centrifugal casting is also really important since it can give manufacturer the general view of solidification process. So solidification of centrifugal casting is also investigated in the thesis work.

No description available.

Noise from information technology (IT) equipment is a significant problem in today's modern society. Active Noise Control (ANC) has shown promise in reducing the effect of IT fan noise on users. Though ANC has been applied to axial fans (such as those found in desktop computers), it has not been applied to centrifugal fans, such as those found in laptop computers. This work applies an ANC method to a centrifugal fan mounted in a mock laptop enclosure. This method is applied in four steps. First, secondary sources are placed in the vicinity of the fan. Second, an accurate model of the radiation from the fan and secondary sources is constructed. Third, the total power radiated from this system is minimized. This creates nodal lines in the vicinity of the fan. Fourth, ANC error sensors are placed on the nodal lines predicted by the model. This creates these nodal lines experimentally, thus creating the minimum power condition. The noise from the exhaust and inlets of the fan will first be controlled individually. Then the method will be applied to the combined system. Global sound power radiation will be measured in all cases.