Plunger pumps are needed for heavy duty sludge pumping at wastewater treatment facilities. America's leading pump manufacturer Wastecorp Inc. brought their plunger pump problem to us in late 2009. It was found that when the ow rate reaches a critical value, the plunger pump starts to generate a clicking noise. A one-dimensional model was built for studying the ow of a typical plunger pump operation. The velocities and pressures are calculated at certain interesting locations. Pressure jumps have been found while opening or closing the valves. The valve motion is then modeled with considerations to its geometry. The results show that as the plunger speed reaches a critical value, the valve moves more rapidly and more likely to hit the wall and generates a noise. We also provide a methodology to study the ow across the valve in higher resolution. A nite-di erence approach to the Navier-Stokes equations are presented with the immersed boundary method. / UOIT

The demand for artificial heart valve replacements is increasing as a result of birth defects, ageing and disease. Collaboration between engineers, biologists and mathematicians is necessary to handle problems related to biocompatibility and fluid dynamics. As a result of the increased demand for artificial heart valves, many new designs have been developed recently. A method to test those designs is to use mathematical modeling. This method has a relatively low-cost and can be used as a preliminary tool before expensive prototypes are created. This research analyzes the use of the numerical modeling software LS-DYNA for large-displacement fluid-structure interaction. It is a preliminary study aimed at the analysis of heart valve dynamics. In particular, a channel with flap model is created in LS-DYNA. The model's physics, convergence and ability to handle large deformations is investigated.

Orientador: José Luiz Gasche / Resumo: Compressores herméticos alternativos são amplamente utilizados em sistemas de refrigeração por compressão de vapor de pequeno e médio porte. O sistema de válvulas automáticas utilizadas para controlar os processos de sucção e descarga é um componente importante deste tipo de compressor. O estudo experimental ou analítico/numérico destes processos é bastante complexo devido, principalmente, à interação fluido-estrutura entre as válvulas e o escoamento de fluido refrigerante. Uma revisão de literatura mostra que este tema ainda merece muita atenção dos pesquisadores, em particular daqueles que necessitam de dados experimentais acurados para validação de metodologias numéricas. Este é o contexto deste trabalho, cujo objetivo é descrever a dinâmica do movimento de um modelo de válvula usada neste tipo de compressor. Sensores óticos foram utilizados para medir o deslocamento instantâneo de modelos de válvulas fabricadas em aço mola SAE 1070 com 0,4 e 0,5 mm de espessura. Os testes foram realizados para escoamentos com números de Reynolds variando de 1.500 a 19.000. A descrição da dinâmica da válvula foi apresentada pela sua amplitude, frequência, pressão máxima à montante do escoamento da válvula e pelo coeficiente de restituição no impacto entre a válvula e o assento. De uma maneira geral, identificamos que a dinâmica da válvula depende significativamente de sua rigidez, do valor de força de pré-carga que está sujeita e do número de Reynolds do escoamento que incide sobre sua sup... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Hermetic reciprocating compressors are widely used in small and medium size vapor compression refrigeration systems. An important component of this type of compressor is the automatic valve system used for controlling the suction and discharge processes. The experimental or analytical/numerical study of this system is complex due to the fluid-structure interaction between the valves and the refrigerant flow. A literature review suggests that this theme still deserves attention from the researchers, in particular for those who need accurate experimental data to validate numerical methodologies. We aim to describe the dynamics of a suction valve model used in this type of compressor. Optical sensors were used to measure the instantaneous displacement of a spring-steel SAE 1070 valve model with 0.4 and 0.5 mm thickness. The tests were performed for Reynolds number of the flow ranging from 1,500 to 19,000. We present the dynamic behavior of the valve by its amplitude, frequency, maximum upstream pressure of the valve, and coefficient of restitution of the impact between valve and seat. Generally, we identify that the valve dynamics depends significantly on its stiffness, precharging force and Reynolds numbers of the flow. The impact between valve and seat also significantly change the dynamics of the movement. / Mestre

Submitted by Gabriel Biancolin Moimas (gabrielmoimas18@gmail.com) on 2018-06-18T11:47:19Z No. of bitstreams: 1 Dissertação.pdf: 13607292 bytes, checksum: 4574d9cd3135ad2562a9648fd1641465 (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-06-18T12:12:00Z (GMT) No. of bitstreams: 1 moimás_gb_me_ilha.pdf: 13607292 bytes, checksum: 4574d9cd3135ad2562a9648fd1641465 (MD5) / Made available in DSpace on 2018-06-18T12:12:00Z (GMT). No. of bitstreams: 1 moimás_gb_me_ilha.pdf: 13607292 bytes, checksum: 4574d9cd3135ad2562a9648fd1641465 (MD5) Previous issue date: 2018-05-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Compressores herméticos alternativos são amplamente utilizados em sistemas de refrigeração por compressão de vapor de pequeno e médio porte. O sistema de válvulas automáticas utilizadas para controlar os processos de sucção e descarga é um componente importante deste tipo de compressor. O estudo experimental ou analítico/numérico destes processos é bastante complexo devido, principalmente, à interação fluido-estrutura entre as válvulas e o escoamento de fluido refrigerante. Uma revisão de literatura mostra que este tema ainda merece muita atenção dos pesquisadores, em particular daqueles que necessitam de dados experimentais acurados para validação de metodologias numéricas. Este é o contexto deste trabalho, cujo objetivo é descrever a dinâmica do movimento de um modelo de válvula usada neste tipo de compressor. Sensores óticos foram utilizados para medir o deslocamento instantâneo de modelos de válvulas fabricadas em aço mola SAE 1070 com 0,4 e 0,5 mm de espessura. Os testes foram realizados para escoamentos com números de Reynolds variando de 1.500 a 19.000. A descrição da dinâmica da válvula foi apresentada pela sua amplitude, frequência, pressão máxima à montante do escoamento da válvula e pelo coeficiente de restituição no impacto entre a válvula e o assento. De uma maneira geral, identificamos que a dinâmica da válvula depende significativamente de sua rigidez, do valor de força de pré-carga que está sujeita e do número de Reynolds do escoamento que incide sobre sua superfície. O impacto entre válvula e assento também altera significativamente a dinâmica do movimento. / Hermetic reciprocating compressors are widely used in small and medium size vapor compression refrigeration systems. An important component of this type of compressor is the automatic valve system used for controlling the suction and discharge processes. The experimental or analytical/numerical study of this system is complex due to the fluid-structure interaction between the valves and the refrigerant flow. A literature review suggests that this theme still deserves attention from the researchers, in particular for those who need accurate experimental data to validate numerical methodologies. We aim to describe the dynamics of a suction valve model used in this type of compressor. Optical sensors were used to measure the instantaneous displacement of a spring-steel SAE 1070 valve model with 0.4 and 0.5 mm thickness. The tests were performed for Reynolds number of the flow ranging from 1,500 to 19,000. We present the dynamic behavior of the valve by its amplitude, frequency, maximum upstream pressure of the valve, and coefficient of restitution of the impact between valve and seat. Generally, we identify that the valve dynamics depends significantly on its stiffness, precharging force and Reynolds numbers of the flow. The impact between valve and seat also significantly change the dynamics of the movement.

A Left Ventricular Assist Device (LVAD) is a mechanical pump that helps patients with heart failure conditions. This rotary pump works in parallel to the ailing heart and provides an alternative path for blood flow from the weak left ventricle to the aorta. The LVAD is controlled by the power supplied to the pump motor. An increase in the pump motor power increases the pump speed and the pump flow. The LVAD is typically controlled at a fixed setting of pump power. This basically means that the controller does not react to any change in the activity level of the patient. An important engineering challenge is to develop an LVAD feedback controller that can automatically adjusts its pump motor power so that the resulting pump flow matches the physiological demand of the patient. To this end, the development of a mathematical model that can be used to accurately simulate the interaction between the cardiovascular system of the patient and the LVAD is essential for the controller design. The use of such a dynamic model helps engineers and physicians in testing their theories, assessing the effectiveness of prescribed treatments, and understanding in depth the characteristics of this coupled bio-mechanical system. The first contribution of this dissertation is the development of a pump power-based model for the cardiovascular-LVAD system. Previously, the mathematical models in the literature assume availability of the pump speed as an independent control variable. In reality, however, the device is controlled by pump motor power which, in turn, produces the rotational pump speed. The nonlinear relationship between the supplied power and the speed is derived, and interesting observations about the pump speed signal are documented. The second contribution is the development of a feedback controller for patients using an LVAD as either a destination therapy or a bridge to transplant device. The main objective of designing this controller is to provide a physiological demand of the patient equivalent of that of a healthy individual. Since the device is implanted for a long period of time, this objective is chosen to allow the patient to live a life as close to normal as possible. The third contribution is an analysis of the aortic valve dynamics under the support of an LVAD. The aortic valve may experiences a permanent closure when the LVAD pump power is increased too much. The permanent closure of the aortic valve can be very harmful to the patients using the device as a bridge to recovery treatments. The analysis illustrates the various changes in the hemodynamic variables of the patient as a result of aortic valve closing. The results establish the relationship between the activity level and the heart failure severity with respect to the duration of the aortic valve opening.

Damper performance is most commonly characterized by the damper’s forcevelocity behaviour. Different damper layouts and valving methods for creating oil flow constrictions bring different physical properties, outside of this conventional measure. The objective of this report is to find which parameters outside of the conventional force/velocity measure can be used to add better comfort and/or control to road- or track-going vehicles. To fulfil the objectives, vehicle comfort and control needed to be defined. Following this, an extensive parameter study was performed, using a full vehicle model in the software CarSim in combination with an Öhlins-written damper model in MATLAB, which was run through a Simulink model connecting the two. The study was performed for two vehicles: a BMWM4 GT4 and a VW ID.3, with five parameters proposed by Öhlins, varied in compression and rebound (giving a total of 10 parameters). Further on, some results were evaluated based on recorded data from a track test with the BMW, where the conclusions from the parameter study were evaluated through physical changes to the dampers. The parameter study showed that parameters P1-2, P9-10, and P5-6 has significant effect, in that order of magnitude. P1-2 and P9-10 all affect comfort and control, whilst P5-6 has minimal effect on control but a larger effect on comfort. The others, P3-4 and P7-8 have minimal effect on almost all metrics used in this study, with merely a few exceptions. In future studies, an analysis of data in time series format could be done. Moreover, a well prepared verification of the parameter study results could also be done. / Dämparprestanda beskrivs oftast av kraft-hastighetsbeteende. Olika ventillayouter och ventilmetoder för att skapa oljeflödesförträngningar ger olika fysikaliska egenskaper, utanför detta konventionella mått. Syftet med denna rapport är att ta reda på vilka parametrar utanför det konventionella kraft/hastighets-måttet som kan användas för att uppnå bättre komfort och/eller kontroll för väg- eller tävlingsbilar. För att uppfylla målen behövde fordonskomfort och kontroll definieras. Efter detta genomfördes en omfattande parameterstudie med en helbils-modell i mjukvaran CarSim i kombination med en Öhlins-utvecklad dämpar-modell i MATLAB, som utvärderades med hjälp av en Simulink-modell vilken sammankopplar de två. Studien utfördes för två fordon: en BMW M4 GT4och en VW ID.3, med fem parametrar föreslagna av Öhlins varierande i kompression och retur (som ger totalt 10 parametrar). Fortsatt utvärderades några resultat baserat på inspelad data från ett bantest med BMW:n, där slutsatserna testades genom fysiska förändringar av dämparna. Simuleringsresulten visade att parameter P1-2, P9-10 och P5-6 har tydligeffekt, i den storleksordningen. P1-2 och P9-10 påverkar både komfort och kontroll, medan P5-6 har minimal effekt på kontroll, men större effekt påkomfort. De andra, P3-4 och P7-8 har minimal effekt på nästan alla mätvärden som används i denna studie, med bara några få undantag. I framtida studier kan en analys av data i tidsserie-format utföras, samt en väl förberedd verifiering av resultaten från parameterstudien.