Este trabalho tem como objetivo analisar e otimizar o desempenho de uma bomba hidráulica de fluxo através do redimensionamento de seu rotor. A partir da teoria acerca do pré-dimensionamento de rotores pelo método clássico (também conhecido como método geométrico) propõe-se uma planilha eletrônica que permite obter as dimensões básicas necessárias para o projeto de um rotor a partir de dados iniciais de operação e coeficientes empíricos. De modo a validar o dimensionamento teórico este trabalho apresenta um estudo de caso em uma bomba-teste. A partir dos dados do software de dimensionamento e recomendações coletadas na bibliografia um novo rotor é desenvolvido tendo como objetivo principal melhorar o desempenho de operação da bomba. Durante o desenvolvimento do novo rotor são utilizados aplicativos CAD e CAM de modo a auxiliar a elaboração do projeto e execução da usinagem. Uma bancada especial de teste de bombas é utilizada no levantamento dos dados experimentais. Os resultados dos ensaios demonstram um ganho máximo na eficiência de operação de 8% e redução de até 0,7 kW na potência da bomba operando com o novo rotor. / This work has as objective to analyze and to optimize the performance of a flow hydraulic pump by the re-design of pumps impeller. From the theory about impeller design by the classic method (also known as geometric method) proposes an electronic spread that allows obtaining the basic dimensions of impeller from initial pump operation data and empiric coefficients In order to validate the theoretical design this work presents a study of case on a pump test. From the design software data and recommendations collected in the bibliography review a new impeller is developed with the main objective to improve the pump performance. During the new impeller development are used applications CAD and CAM to aid the elaboration of the design and the execution of machining. A special hydraulic pump test bench is used to collect experimental data. The tests results shown a maximum gain of 8% in the efficiency of operation and a reduction of until 0,7 kW in the pump power consumption operating with the new impeller.

This thesis presents models and algorithms necessary to simulate the five-axis flank milling of jet-engine impellers in a virtual environment. The impellers are used in the compression stage of the engine and are costly, difficult to machine, and time-consuming to manufacture. To improve the productivity of the flank milling operations, a procedure to predict and optimize the cutting process is proposed. The contributions of the thesis include a novel cutter-workpiece engagement calculation algorithm, a five-axis flank milling cutting mechanics model, two methods of optimizing feed rates for impeller machining tool paths and a new five-axis chatter stability algorithm. A semi-discrete, solid-modeling-based method of obtaining cutter-workpiece engagement (CWE) maps for five-axis flank milling with tapered ball-end mills is developed. It is compared against a benchmark z-buffer CWE calculation method, and is found to generate more accurate maps. A cutting force prediction model for five-axis flank milling is developed. This model is able to incorporate five-axis motion, serrated, variable-pitch, tapered, helical ball-end mills and irregular cutter-workpiece engagement maps. Simulated cutting forces are compared against experimental data collected with a rotating dynamometer. Predicted X and Y forces and cutting torque are found to have a reasonable agreement with the measured values. Two offline methods of optimizing the linear and angular feeds for the five-axis flank milling of impellers are developed. Both offer a systematic means of finding the highest feed possible, while respecting multiple constraints on the process outputs. In the thesis, application of these algorithms is shown to reduce the machining time for an impeller roughing tool path. Finally, a chatter stability algorithm is introduced that can be used to predict the stability of five-axis flank milling operations with general cutter geometry and irregular cutter-workpiece engagement maps. Currently, the new algorithm gives chatter stability predictions suitable for high speed five-axis flank milling. However, for low-speed impeller machining, these predictions are not accurate, due to the process damping that occurs in the physical system. At the time, this effect is difficult to model and is beyond the scope of the thesis. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

This thesis deals with redesigning of the current technological manufacturing process and subsequent production of a centrifugal impeller of a small tubojet engine. Thesis is divided into three main parts. First part deals with the theoretical background of the turbojet engines and the centrifugal impeller. Next part is focused on the proposed manufacturing technology of the centrifugal impeller using machining. Final part of the thesis deals with evaluation of the achieved goals.

This master’s thesis is focused on modeling and creation of NC programs for machining of the impellers. Software used for modeling is CATIA V5R20 from Dassault Systémes company. For creation of NC programs software PowerMILL from Delcam company is used. Verification of functionality of created NC programs is done in Sinumerik 840d control system.

<p>The primary objective of this research was to shed light on the changes in performance observed in a high-speed, centrifugal compressor that occur during the transition from subsonic to transonic operating conditions, using experimental data collected on a research compressor developed by Honeywell Aerospace, as well as results from a numerical model of the compressor.</p> <p> An understanding of the flow behavior in transonic centrifugal compressors is critical as the drive for higher stage pressure ratios while maintaining a compact size results in higher rotational speeds and increased aspect ratios in the inducer of the impeller. Both of these design trends result in higher relative Mach numbers near the impeller leading edge, resulting in the formation of shocks and an increasingly complex flow field. Since it is necessary to maintain high efficiency and adequate surge margin at these conditions—to ensure the compressor is stable across the full operating range—it is important to understand the effects of the transition from subsonic to supersonic flow on performance and stability. Due to the limited availability of research in the open literature regarding transonic centrifugal impellers, especially experimental studies, these behaviors are still not fully understood.</p> <p>Experimental data collected during steady state operation as well as during speed transients, showed a sudden decrease in the variance of the unsteady pressure field throughout the compressor, but most dramatically in the inducer shroud. Analysis of the performance also showed a significant increase in impeller efficiency of approximately 2 points as speed was increased from 80% to 90% of the design speed. Temperature measurements upstream of the impeller leading edge indicated a dramatic reduction in the degree of flow recirculation in the same speed range, indicating the increase in performance is related to a decrease in the blockage near the impeller leading edge. A low pressure region was also observed in the inducer passage, which disappeared upon transition to the transonic operating regime, this coupled with decreased inducer static pressure rise and relative diffusion at lower speeds, strongly indicates that increased loss in the inducer at lower speeds is responsible for the observed performance deficiency during subsonic operation.</p> <p>Analysis of the numerical results revealed that the low pressure region in the inducer may be attributable to the interaction between the inlet shroud boundary layer and the low momentum tip leakage flow in the impeller passage, which at lower speeds, results in the tip leakage flow forming a large recirculation region in the inducer passage. It was also determined that the step change in instability coincides with the inducer shock extending to the shroud and reducing the strength of the interaction between the low momentum regions in the inlet and impeller passage, thereby allowing the tip leakage flow to form into a vortex and preventing the development of the recirculation region in the inducer. </p> <p>This research provides a possible explanation for the observed instability in the compressor, which may allow for further testing of techniques to mitigate the instability caused by the blockage in the inducer, such as casing treatment, bleed, or flow injection into the inducer shroud.</p>

The engine cooling system is an important part of the engine’s performance to achieve optimum temperatures in cylinders and provide cooling to subsystems. With increasing emission demands from legislation, further development of the cooling system is necessary. An important component in the engine cooling system is the pump that produces the necessary flow rate to cool down the components. The pump is connected to the drive shaft with a pulley so improvements in the pumps efficiency will directly affect the fuel efficiency of the vehicle. With more variations and increasingly complex system design different performance stages of the pump are necessary to provide desired flow rates depending on system design. To enable a rapid design of performance stages of pumps, a calculation model is constructed to predict the performance of an engine cooling pump based on the geometry of the impeller and pump casing. The model includes the main head losses that occur within a centrifugal pump both in the impeller and pump casing. The model is based on quasi one-dimensional calculations of velocity triangles in impeller and pump casing. The head losses are modelled with correlations from literature that are compared to test data from reference pumps. The developed model provides a pump - , hydraulic efficiency – and power curve based on main geometrical parameters. A design tool and procedure is constructed to suggest main geometry parameters for the impeller based on a desired operational point. The design tool is constructed on design coefficients based on reference pumps test data and correlations from literature. Together with the calculation model an impeller flow channel can be designed to achieve the desired operational point. Two impellers are designed and manufactured by rapid prototyping that are tested by an experimental test to verify the model and design tool. The result show that the calculation model captures the general behaviour of the pump curve and is within 1-10% accuracy. The calculation model and the design tool are designed to assess the performance of the main geometry parameters in the impeller and pump casing. Further optimization and studies of the complete flow field to assess secondary flows and cavitation behaviour can be done by numerical methods. The calculation model and design tool constructed provides a rapid way of designing new impellers and an easy method to perform parameter studies on changes in impeller geometry. / Motorns kylsystem är en viktig del av motorns prestanda för att uppnå optimal temperatur i cylindrarna och för att tillhandahålla kylning till de olika delsystem. Med ökade utsläppskrav från lagstiftning har kylsystemet och dess fortsatta utveckling en viktig roll för att möta dessa. En viktig komponent i kylsystemet är pumpen som tillhandahåller den nödvändiga flödeshastigheten för att kyla ner de ingående komponenterna.  Pumpen drivs av drivaxeln med remdrift vilket medför att verkningsgraden på pumpen direkt påverkar bränsleförbrukningen. Utvecklingen går mot att kylsystemet blir mer varierat och snabbt ska kunna anpassa sig till nya kylbehov vilket medför att olika prestandasteg på pumpen är nödvändiga för att kunna garantera tillräcklig flödeshastighet. För att förkorta ledtiderna i processen av att designa olika prestandasteg av en kylvätskepump har en beräkningsmodell utvecklats som kan förutsäga pumpens prestanda baserat på impellerns och pumphusets geometri. I modellen ingår de största strömningsförlusterna som uppstår i en centrifugalpump både i impellern och i pumphuset. För att modellera förlusterna som uppstår används korrelationer som är anpassade och korrelerade mot test data från referenspumpar. Modellen beräknar en pumpkurva, hydraulisk verkningsgradskurva och en effektkurva baserat på pumpens geometri. Ett designverktyg och ett tillvägagångssätt för att designa impellrar är också framtaget som är baserat på beräkningsmodellen samt en given designpunkt. Designverktyget använder olika designkoefficienter som är baserade på tidigare test data samt etablerade korrelationer. Tillsammans med beräkningsmodellen kan flödeskanalen designas baserat på en given designpunkt av flöde, tryckhöjd och rotationshastighet. Med hjälp av designverktyget är två impellrar designade och tillverkade genom friformsframställning vilka provas för att verifiera modellen och designverktyget. Resultatet visar att beräkningsmodellen kan prediktera pumpkurvans beteende med en noggrannhet på 1-10%. Beräkningsmodellen samt designverktyget är baserat på de huvudsakliga geometriparametrarna i impellern och pumphuset. För att fullständigt analysera flödesfältet i pumpen samt optimera designen och bedöma kavitationsrisken krävs en numerisk analys.  Beräkningsmodellen och designverktyget ger ett snabbt tillvägagångssätt för att designa och utvärdera prestandan i en pump samt göra enkla parameterstudier av designparameterar i pumpen.

In this study, agitation of solutions using different impeller and tank geometry were investigated experimentally in terms of hydrodynamics, macromixing time and aeration characteristics. In the first set of experiments a cylindrical vessel equipped with two types of hydrofoil and a hyperboloid impeller or their combinations were used. Vessel and impeller diameters and water level were 300, 100 and 300 mm, respectively. At the same specific power consumption, 163 W/m3, the so called hydrofoil 1 impeller provided the shortest mixing time at 7.8 s. At the top hydrofoil 1 impeller submergence of 100 mm, the hyperboloid impeller combination of it was the most efficient by a mixing time of 10.0 s at 163 W/m3. Ultrasound Doppler velocimetry and the lightsheet experiments showed that the hydrofoil 1, hydrofoil 2 impellers and the stated impeller combination provided a complete circulation all over the tank. Macromixing measurements were performed in square vessel for Generation 5 low and high rib and Generation 6 hyperboloid impellers. Vessel length, impeller diameters and water level were 900, 300 and 450 mm, respectively. At the same specific power consumption, 88.4 W/m3, Generation 6 mixer provided the lowest mixing time at 80.5 s. Aeration experiments were performed in square tank for Generation 5 low rib and Generation 6 hyperboloid impellers equipped with additional blades. With increasing flow number, the differences between the performances at different rotational speeds became smaller for each type of mixer. At similar conditions the transferred oxygen amount of Generation 6 impeller was about 20% better.

A literatura corrente possui informações limitadas sobre o projeto da área de troca térmica de tanques com jaqueta, serpentina helicoidal, serpentina espiral e chicana tubular vertical, em operação com fluidos não-Newtonianos. A presente tese teve por objetivo principal analisar a transferência de calor, potência consumida e ampliação de escala em tanques com impulsores mecânicos na agitação de fluidos não-Newtonianos com duas superfícies de transmissão de calor, chicana tubular vertical e serpentina em espiral. O trabalho também visou fornecer métodos de ampliação de escala de tanques com agitação para fluidos não-Newtonianos que sigam o modelo reológico da lei das potências. A unidade experimental contemplou dois tanques de acrílico, com volume de 10 litros e 50 litros, respectivamente, chicanas tubulares verticais e serpentina em espiral. Os impulsores mecânicos utilizados foram o axial com 4 pás inclinadas a 45° e o radial turbina com 6 pás planas. Como fluidos utilizaram-se soluções aquosas de carboximetilcelulose (0,5%, 1,0% e 1,5%), solução aquosa de carbopol 940 (1,5%), solução aquosa de sacarose (50%) e água. Todos os experimentos foram conduzidos em batelada. Com os dados obtidos, empregou-se o uso de regressões para a obtenção da Equação de Nusselt, as quais forneceram valores de coeficiente de determinação ajustados entre 0,83 e 0,89 com Reynolds no intervalo de 20 a 405000, Prandtl na faixa de 4 a 6400 e índice reológico do modelo da lei das potências entre 0,45 e 1,00. Observou-se que no aquecimento realizado com a chicana tubular vertical, o impulsor radial forneceu coeficientes de convecção 20% acima quando comparado com o impulsor axial, entretanto o consumo de potência foi cerca de 66% maior em relação ao impulsor axial. No caso da serpentina espiral, o impulsor axial promoveu coeficientes de convecção por volta de 15% superiores em relação ao impulsor radial com um consumo de potência 65% menor. Desse modo, em processos em que não é necessária uma elevada turbulência, recomenda-se o uso do impulsor axial com a serpentina espiral, porém, se o processo demandar uma turbulência significativa, deve-se usar o impulsor radial com a chicana tubular vertical. Em uma última análise, os modelos não-lineares obtidos para ampliação de escala forneceram erros entre 11% e 20% na predição da rotação no tanque industrial, os quais são válidos para Reynolds modificados de Metzner e Otto (1957) na faixa de 20 a 4000 e para fluidos não-Newtonianos pseudoplásticos com índices reológicos entre 0,45 e 1,00. / Current literature has limited information on the design of the thermal exchange area of tanks with jacket, helical coil, spiral coil and vertical tuber baffle, in operation with non-Newtonian fluids. The main purpose of this thesis was to analyze heat transfer, power consumption and scale-up in tanks with mechanical impellers in the agitation of non-Newtonian fluids with two heat transfer surfaces, vertical tube baffle and spiral coil. The work also aimed to provide methods of scale-up tank scale with agitation for non-Newtonian fluids that follow the rheology model of the law of powers. The experimental unit included two acrylic tanks, with a volume of 10 liters and 50 liters, respectively, vertical tube baffles and spiral coil. The mechanical impellers used were the 45° pitched blade turbine (PBT) and the Rushton turbine (RT). Aqueous solutions of carboxymethylcellulose (0.5%, 1.0% and 1.5%), aqueous solution of carbopol 940 (1.5%), aqueous solution of sucrose (50%) and water were used as fluids. All the experiments were conducted in batch. With the obtained data, we used the regressions to obtain the Nusselt Equation, which provided coefficient of determination values adjusted between 0.83 and 0.89 with Reynolds in the range of 20 to 405000, Prandtl in the range of 4 to 6400 and rheological index of the power law model between 0.45 and 1.00. It was observed that in the heating performed with the vertical tube baffle, the RT provided convection coefficients 20% higher when compared to the axial impeller, however the power consumption was about 66% higher in relation to the PBT. In the case of the spiral coil, the PBT promoted convection coefficients around 15% higher than the RT with 65% lower power consumption. Thus, in processes where high turbulence is not required, it is recommended to use the PBT with the spiral coil, but if the process requires significant turbulence, the RT must be used with the vertical tubular chassis. In a final analysis, the nonlinear models obtained for scaling provided errors between 11% and 20% in the prediction of rotation in the industrial tank, which are valid for Metzner and Otto (1957) modified Reynolds in the range of 20 to 4000 and for non-Newtonian pseudoplastic fluids with rheological indexes between 0.45 and 1.00.

A literatura corrente possui informações limitadas sobre o projeto da área de troca térmica de tanques com jaqueta, serpentina helicoidal, serpentina espiral e chicana tubular vertical, em operação com fluidos não-Newtonianos. A presente tese teve por objetivo principal analisar a transferência de calor, potência consumida e ampliação de escala em tanques com impulsores mecânicos na agitação de fluidos não-Newtonianos com duas superfícies de transmissão de calor, chicana tubular vertical e serpentina em espiral. O trabalho também visou fornecer métodos de ampliação de escala de tanques com agitação para fluidos não-Newtonianos que sigam o modelo reológico da lei das potências. A unidade experimental contemplou dois tanques de acrílico, com volume de 10 litros e 50 litros, respectivamente, chicanas tubulares verticais e serpentina em espiral. Os impulsores mecânicos utilizados foram o axial com 4 pás inclinadas a 45° e o radial turbina com 6 pás planas. Como fluidos utilizaram-se soluções aquosas de carboximetilcelulose (0,5%, 1,0% e 1,5%), solução aquosa de carbopol 940 (1,5%), solução aquosa de sacarose (50%) e água. Todos os experimentos foram conduzidos em batelada. Com os dados obtidos, empregou-se o uso de regressões para a obtenção da Equação de Nusselt, as quais forneceram valores de coeficiente de determinação ajustados entre 0,83 e 0,89 com Reynolds no intervalo de 20 a 405000, Prandtl na faixa de 4 a 6400 e índice reológico do modelo da lei das potências entre 0,45 e 1,00. Observou-se que no aquecimento realizado com a chicana tubular vertical, o impulsor radial forneceu coeficientes de convecção 20% acima quando comparado com o impulsor axial, entretanto o consumo de potência foi cerca de 66% maior em relação ao impulsor axial. No caso da serpentina espiral, o impulsor axial promoveu coeficientes de convecção por volta de 15% superiores em relação ao impulsor radial com um consumo de potência 65% menor. Desse modo, em processos em que não é necessária uma elevada turbulência, recomenda-se o uso do impulsor axial com a serpentina espiral, porém, se o processo demandar uma turbulência significativa, deve-se usar o impulsor radial com a chicana tubular vertical. Em uma última análise, os modelos não-lineares obtidos para ampliação de escala forneceram erros entre 11% e 20% na predição da rotação no tanque industrial, os quais são válidos para Reynolds modificados de Metzner e Otto (1957) na faixa de 20 a 4000 e para fluidos não-Newtonianos pseudoplásticos com índices reológicos entre 0,45 e 1,00. / Current literature has limited information on the design of the thermal exchange area of tanks with jacket, helical coil, spiral coil and vertical tuber baffle, in operation with non-Newtonian fluids. The main purpose of this thesis was to analyze heat transfer, power consumption and scale-up in tanks with mechanical impellers in the agitation of non-Newtonian fluids with two heat transfer surfaces, vertical tube baffle and spiral coil. The work also aimed to provide methods of scale-up tank scale with agitation for non-Newtonian fluids that follow the rheology model of the law of powers. The experimental unit included two acrylic tanks, with a volume of 10 liters and 50 liters, respectively, vertical tube baffles and spiral coil. The mechanical impellers used were the 45° pitched blade turbine (PBT) and the Rushton turbine (RT). Aqueous solutions of carboxymethylcellulose (0.5%, 1.0% and 1.5%), aqueous solution of carbopol 940 (1.5%), aqueous solution of sucrose (50%) and water were used as fluids. All the experiments were conducted in batch. With the obtained data, we used the regressions to obtain the Nusselt Equation, which provided coefficient of determination values adjusted between 0.83 and 0.89 with Reynolds in the range of 20 to 405000, Prandtl in the range of 4 to 6400 and rheological index of the power law model between 0.45 and 1.00. It was observed that in the heating performed with the vertical tube baffle, the RT provided convection coefficients 20% higher when compared to the axial impeller, however the power consumption was about 66% higher in relation to the PBT. In the case of the spiral coil, the PBT promoted convection coefficients around 15% higher than the RT with 65% lower power consumption. Thus, in processes where high turbulence is not required, it is recommended to use the PBT with the spiral coil, but if the process requires significant turbulence, the RT must be used with the vertical tubular chassis. In a final analysis, the nonlinear models obtained for scaling provided errors between 11% and 20% in the prediction of rotation in the industrial tank, which are valid for Metzner and Otto (1957) modified Reynolds in the range of 20 to 4000 and for non-Newtonian pseudoplastic fluids with rheological indexes between 0.45 and 1.00.

No description available.