Submitted by ALCIDES MARANGONI JUNIOR (amarangoni@ifma.edu.br) on 2018-05-04T22:44:01Z No. of bitstreams: 1 Dissertacao_Alcides_Marangoni_Junior_2018.pdf: 930282 bytes, checksum: 1c8e75840d460aee6513b5562a9d1de8 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-05-07T11:11:47Z (GMT) No. of bitstreams: 1 marangonijunior_a_me_jabo.pdf: 930282 bytes, checksum: 1c8e75840d460aee6513b5562a9d1de8 (MD5) / Made available in DSpace on 2018-05-07T11:11:48Z (GMT). No. of bitstreams: 1 marangonijunior_a_me_jabo.pdf: 930282 bytes, checksum: 1c8e75840d460aee6513b5562a9d1de8 (MD5) Previous issue date: 2018-04-27 / Outra / O uso de pulverizadores costais manuais no Brasil é frequente em todas as propriedades rurais. Entretanto, são escassos os trabalhos de pesquisa que avaliem as suas características de trabalho, sobretudo com o modelo de ponta de pulverização que equipa os pulverizadores de fábrica e nas condições de pressão de trabalho predominantes na utilização. Desta forma, o objetivo deste trabalho foi avaliar quanto os modelos de pontas e a pressão de trabalho influenciam na qualidade da distribuição de caldas fitossanitárias com pulverizadores costais manuais. Foram avaliadas em mesa de deposição quatro modelos de pontas de pulverização (jato plano convencional - Magnojet TP 110015; jato plano defletor - Teejet TT 110015; jatos cônicos vazios - TeeJet TXA 80015 e “chapinha” original), a 1, 2, 3 e 4 bar de pressão. As análises do perfil de distribuição dos jatos foram realizadas por simetria e o coeficiente de variação analisado pelo teste de Tukey (p<0,05). Os modelos de pontas de pulverização e pressão de trabalho influenciaram em mais de 100% os valores de uniformidade de distribuição da calda, e cerca de 50% na largura da faixa útil de tratamento fitossanitário. Dentre os modelos avaliados neste trabalho, o de jato defletor é o que apresenta o melhor conjunto de características para ser indicado a equipar os pulverizadores costais manuais para os tratamentos fitossanitários a campo. / Manual backpack sprayers are widely used in rural properties in Brazil. However, studies that assess their working characteristics, especially spray tip models and working pressure conditions, are scarce. Thus, the aim of this study was to assess how much the working pressure and spray tips influence the distribution quality of phytosanitary spray solutions in manual backpack sprayers. Four spray nozzles (standard flat-fan Magnojet TP110015, turbo flat-fan TeeJet TT110015, hollow-cone TeeJet TXA80015, and disc-core) were assessed in a patternator table at 1, 2, 3, and 4 bar. Distribution profile analyses of sprays were performed by symmetry and the coefficient of variation analyzed by the Tukey’s test (p<0.05). Spray tip models and working pressure influenced in more than 100% the distribution uniformity values of spray solution and in about 50% the useful bandwidth of the phytosanitary treatment. Among the models assessed in this study, the turbo flat-fan spray nozzle presents the best set of characteristics to be indicated for manual backpack sprayers aiming at field phytosanitary treatments.

En Tunisie, comme dans plusieurs pays méditerranéens, la céréaliculture est une activité très consommatrice de pesticides, (63% de la consommation totale de l'agriculture tunisienne). Par conséquent, il est nécessaire d'étudier le devenir des pesticides appliqués afin de réduire les quantités perdues dans l'environnement tout en maintenant un niveau acceptable de l'efficacité des traitements. Plusieurs études ont montré qu'après leur éjection par la buse, les gouttes sont plus ou moins soumises aux phénomènes de dérive et de perte au sol pendant l'application. La partie principale de ce travail est basée sur le développement et la validation d'un modèle capable de calculer les dépôts, la volatilisation, (évaporation et pertes vers l'air) sous le vent, en grandes cultures. Le modèle DriftL a été alors construit sous le logiciel SciLab, version 5.03. Il a été calé à partir de mesures réalisées sous des conditions contrôlées en soufflerie et a bénéficié d'une validation expérimentale. Une deuxième partie a étudié expérimentalement les pertes directes au sol et la rétention sur les plantes en conditions de laboratoire. Comme le travail mené en soufflerie, elle a permis de mettre en évidence une relation entre la granulométrie de la pulvérisation, la hauteur des buses, les variables microclimatiques et les dépôts mesurés dans les compartiments air, sol et plante. Pour effectuer les mesures, une démarche expérimentale a été mise en place afin de choisir la méthode de travail. Après de nombreux tests, un collecteur a été sélectionné pour chaque compartiment. Une rampe mobile a été également fabriquée pour jouer le rôle du pulvérisateur dans les conditions de laboratoire. Les mesures effectuées au champ ont permis de valider des calculs de DriftL et des résultats obtenus au laboratoire / In Tunisia, as in many Mediterranean countries, cereal is a very very pesticides intensive crop (63% of overall Tunisian agriculture consumption). Consequently, it is necessary to study the fate of applied pesticides to reduce the losses to the environment and maintain an acceptable effectiveness of treatments. Several studies have shown that after their ejection from the nozzle, drops are subject to drift and ground loss during application.The main part of this work is based on the development and validation of a model to calculate drift in field crops. Thus was developed our model, DriftL, under Scilab software, version 5.03. It has been stalled from controlled conditions measurements in a wind tunnel and received experimental validation. A second part studied experimentally the direct soil losses and plants retention under laboratory conditions. As well as the wind tunnel results, it has showed a relationship between the size of the drops VMD, the microclimatic variables and deposits in the concerned compartments.To measure deposits, an experimental approach has been established in order to choose the work method. After numerous tests, one collector was selected for each compartment. A device was also built to replace the sprayer in laboratory conditions. The field measurements were used to discuss DriftL calculations and laboratory results.

Biogas is a renewable gaseous fuel with low calorific value and a low burning velocity. This burning characteristic makes stabilizing biogas flame difficult especially in high flow velocity applications, and hence presenting a real challenge for power generation systems. This thesis presents an experimental investigation of the effect of burner geometry (i.e., fuel nozzle geometry and swirl strength of the co-airflow) on the stability limits of a turbulent non-premixed biogas surrogate flame. Three different co-airflow swirl strengths (S = 0, 0.31, 0.79) were implemented using swirl generators with vane angle of 0º, 25º and 50º, respectively. Six different fuel nozzle geometries were used in order to study the effect of fuel jet centerline velocity on the stability limits of a low swirling (i.e., 25º) non-premixed biogas flame. Moreover, the biogas surrogate fuel composition was kept constant (60% CH4 and 40% CO2 by volume) using a mixture of pure methane and carbon dioxide gases. The results of the effect of co-airflow swirl strength on the stability limits of biogas flame revealed that the swirl plays an important role on both the flame mode and its stability limits for both attached and lifted flames. The experimental results revealed that at low swirl strength the attached flame lifts off and stabilizes at a distance above the burner, while at high swirl strength the flame remains attached but shortens and burns blue. Overall, the high swirl attached flame was found to stabilize over a wider range of flow conditions in comparison to the attached and lifted flame produced by low swirl. Importantly, the central fuel jet characteristics (induced by varying the fuel nozzle geometry) were found to drastically influence the upper and lower blowout limits of the low swirl biogas lifted flame, while multi-hole fuel nozzle geometry was found to significantly enhance the stability ranges. 2D PIV data was used to explain the stability limits and the experimental flame results were used to propose semi-empirical correlations capable of describing the turbulent biogas blowout stability limits. / October 2016

The present thesis focuses on the interaction between refractory and liquid steel. The aim of this work is to understand the interaction behavior between refractory and liquid steel regarding steel cleanliness. The effect of different refractories on different inclusions in Al-killed steel was studied in a furnace. The sintering mechanism of filler sand were also investigated in laboratory. In the industrial trials, the attachments of different oxides on the walls of submerged entry nozzle (SEN) were discussed in the cases of high strength low alloy steel (HSLA) and ultra-low carbon steel (ULC). It is found that the effect of alumina and spinel refractory on all the three types of inclusions is very little, while MgO refractory influences the inclusions depending on the activity of dissolved oxygen in liquid steel. At low oxygen level, alumina inclusions could transform into spinel inclusions with the help of MgO refractory, while the effect on spinel and calcium aluminate inclusions is not evident. On the other hand, when the activity of dissolved oxygen is high enough, the evolution of spinel inclusions from alumina inclusions could not be seen. The reaction between chromite and silica grains leading to liquid formation is the main mechanism for the sintering of filler sand. The factors viz. steel composition, silica size and content, operation temperature and process holding time have a strong influence on the sintering of the filler sand. Smaller size and higher content of silica in sand, steel grades containing higher Mn and Al contents, higher temperature and longer holding time would result in serious sintering. The choice of the sand needs to take those factors into account. The results show that solid alumina particles are always agglomerated on the inner wall of SEN in the case of ULC steel. The top slag with high FeO and MnO contents is considered as the main reason of this kind of attachments. The removal of slag might be a good method to avoid the attachments. In the case of HSLA steel, liquid calcium aluminate inclusions could attach on the inner wall of SEN as well. The smoothness of the inner wall of the SEN holds the key of liquid attachments. In addition, the attachment situation on the outer wall of SEN depends on the operations. The oxygen entrainment through the mold powder would result in the formation of plate-like alumina attachments. The control of reoxidation due to oxygen entrainment would help to avoid this situation. / <p>QC 20160816</p>

Abrasive blasting process optimization is aimed at establishing relationships between applied feed rates and resulting productivity and consumption rates. It is clear that the high costs of disposal of the multimedia wastes generated by the dry abrasive blasting processes are of increasing concern in the future of shipbuilding industry. In such circumstances essential care has to be given to all components of the process to enhance productivity and decrease consumption rates. This study discusses most of the process components and their respective effects on blasting productivity and consumption rates briefly and concentrates on two important process parameters, nozzle pressure and abrasive feed rate. Feed rate is a vital process parameter that contributes to the productivity and consumption rates of the process. Subsequently feed rates also can significantly impact the costs bore by Shipbuilding Industry in the form of disposal and environmental costs. Most commonly used abrasives were identified through a rigorous survey and were opted to be used in this study. The approach adopted to develop the relationships consists of a mass balance equation between the expended abrasives and disposed wastes to clean a predetermined area of a plate. The obtained data was further analysed to develop productivity rates and consumption rates for each sample runs. The data was then evaluated to formulate relationships that would enable the derivation of optimum feed rates for desirable productivity and reduced waste generation.

Progress in conventional rocket engine technologies, based on constant pressure combustion, has plateaued in the past few decades. Rotating detonation engines (RDEs) are of particular interest to the rocket propulsion community as pressure gain combustion may provide improvements to specific impulse relevant to booster applications. Despite recent significant investment in RDE technologies, little research has been conducted to date into the effect of nozzle design on rocket application RDEs. Proper nozzle design is critical to capturing the thrust potential of the transient pressure ratios produced by the thrust chamber. A computational fluid dynamics study was conducted based on hotfire conditions tested in the Purdue V1.3 RDE campaign. Three geometries were investigated: nozzleless/blunt body, internal-external expansion (IE-) aerospike, and flared aerospike. The computational study found the RDE's dynamic exhaust plume enhances the ejection physics beyond that of a typical high pressure device. For the nozzleless geometry, the base pressure was drawn down below constant pressure estimates, increasing the base drag on the engine. For the aerospike geometries, the occurrance of flow separation on the plug was delayed, which has ramifications on nozzle design for operation at a range of pressure altitudes. The flared aerospike design, which has the ability to achieve much higher area ratios, was shown to have potential performance benefits over the limited IE-aerospike geometry. A new test campaign with the Purdue RDE V1.4 was designed with instrumentation to capture static pressures on the nozzleless and aerospike surfaces. These results were used to validate the results from the computational study. The computational and experimental studies were used to identify new flow physics associated with a rocket RDE important to future nozzle design work. Future computational work is necessary to explore the effect of different parameters on the nozzle performance. More testing, including with an altitude simulation chamber, would help quantify the possible benefit of new aerospike nozzle designs, including the flared aerospike geometry.

A condição ótima de funcionamento de uma tubeira em um motor foguete com escoamento isentrópico, implica que a velocidade na garganta (seção de menor área) seja equivalente à velocidade do som local, condição de Mach 1 e bocal engasgado. Pode-se alcançar essa condição reduzindo a área da seção do escoamento até a área crítica, velocidade sônica. Após a garganta acontece a expansão e se alcança velocidades supersônicas no divergente. Para manter a condição de Mach 1 na garganta em motores foguetes, trabalha-se com pressões superiores à necessária para se engasgar o bocal. Isto ocorre porque tenta-se compensar instabilidades ou variações de volumes produzidos na combustão ou queima. Usando uma pressão de trabalho maior, impõe-se que a condição de Mach 1 fique mantida durante toda a queima do combustível, isso implica em usar tubos mais resistentes à pressão e maior massa do tubo-motor. Observou-se experimentalmente que em algumas situações construtivas se podem modificar a pressão e temperatura necessárias para engasgar o bocal aumentando o comprimento da garganta. O comprimento do estrangulamento pode estabelecer uma condição para formação e evolução da camada limite e esta condição restringir a área nominal, modificando o regime do escoamento. Um equipamento especialmente desenvolvido para esse ensaio compara resultados de cinco modelos de motores, divididos em dois grupos, cada grupo com áreas de entrada, garganta e saída iguais, porém com comprimentos diferentes de garganta. Em análise experimental, observou-se que a pressão de trabalho e a temperatura são influenciadas pelo comprimento da garganta, interferindo na relação entre as pressões internas e de garganta e apresentando condições de engasgamento mensuráveis. Essas medidas foram conduzidas no presente estudo de doutorado. / The optimum operational condition of a rocket motor nozzle with isentropic flow implies that the velocity at the throat (the section with smallest area) is equivalent to the speed of the local sound. This speed is also called Mach 1 and it is said that at this condition the nozzle is choking. One can achieve this condition by reducing the cross-sectional area of the flow to the critical area resulting in a sonic speed. Beyond the nozzle throat, in the divergent section of the motor, flow expansion occurs and reaches supersonic speeds. To maintain the condition of Mach 1 at the throat, higher pressures than the one necessary to choke the nozzle are applied. This practice is done in order to compensate for jitter or variations of volumes produced in the combustion process. Using a higher operating pressure guarantees that a Mach 1 speed is maintained throughout the combustion process. Consequently, due to this higher operating pressure, more resistant tubes are needed to withstand this higher pressure and an increase in the motor weight is inevitable. It was observed experimentally that some constructional modifications of the motor can alter the pressure and temperature required for choking. This was noted with increasing the bottleneck length of the nozzle throat which was able to establish a condition for the formation and evolution of the boundary layer, restricting the nominal area and thus modifying the flow regime. In this study, the results of five engine models are compared using a specially designed equipment. The rockets were divided into two groups, each with equal inlet, throat, and exit areas, but having different throat lengths. In experimental analysis, it was observed that the working pressure and temperature are influenced by the length of the throat, interfering in the relationship between the internal pressures and throat presenting measurable choking conditions which were conducted in this doctorate thesis study.

The numerical simulation and modeling of plasma detachment from a magnetic nozzle is presented. The detachment problem is of key importance to the plasma-based propulsion concepts that employ a guiding magnetic field to control plasma flow and motivated by the needs of the VASIMR (Variable Specific Impulse Magnetoplasma Rocket) project. The detachment of the plasma exhaust is required to produce directed thrust. In the present scenario plasma can stretch the magnetic field lines to infinity, similar to the solar wind. In order to extend the magnetic nozzle model beyond the limitations of analytic theory, a numerical code is developed to simulate steady-state kinetic plasma flows and to evaluate nozzle efficiency. The direct solution of a steady-state problem, as opposed to an initial value problem, eliminates the need to deal with transient phenomena that are of secondary importance for continuously operated plasma thrusters. The new simulation code is verified against the analytic results and then used to model the plasma behaviour for the conditions of the Detachment Demonstration Experiment (DDEX) at the NASA Marshall Propulsion Research Center, Huntsville, Alabama. / text

Electrospray ionization (ESI) has been an invaluable technique to mass spectrometry (MS) especially for analyzing large bio-molecules with unparalleled sensitivity, robustness, and simplicity. Great effort in the development of ESI technique has been devoted in the emitter design, as its shape and geometry have proved pivotal to the electrospray performance and further MS detection. Intrinsic problems for the traditional single-hole emitters including clogging and low throughput limit the applicability of the technique. To address this issue, the current project is focused on developing multiple electrospray (MES) emitters for improved ESI-MS analysis. In this thesis, joint work of both computational fluid dynamic (CFD) simulations for electrospray and offline electrospray experiments for spray current measurement were performed. Numerical simulations were used to test the effect of various emitter designs on electrospray performance and the laboratory results serve as a guide and validation. The CFD code was based on Taylor-Melcher leaky dielectric model (LDM) and the transient electrospray process was successfully simulated. The method was first validated via a 750 μm inner diameter (i.d.) emitter and further applied to a 20 μm i.d. model. Different stages of the electrospray process were visually demonstrated and the quantitative investigations for the change of spray current under various applied electric fields and flow rates share good agreement with previous simulations and measurements. Based on the single-aperture prototype, MES simulations were performed with 2-hole and 3-hole emitters. Simulation predictions compared favorably with the experimental results. Evidence from this work has proved that CFD simulation can be used as an effective numerical tool to test emitter designs for MES. The benchmarking result on the successful simulation of a microscale emitter electrospray achieved in this work is believed to be the smallest scale of the dynamic simulation for electrospray published to date. / Thesis (Master, Chemistry) -- Queen's University, 2011-12-23 13:36:08.754

The welding of austenite stainless steel often results in large amount of welding distortion due to its high thermal expansion coefficient and low thermal conductivity. This has created great difficulty in the dimensional control of the welded stainless steel structure, ending up with high manufacturing cost. Researches on the welding distortion of stainless steels were very limited, especially for large weld structures with complex component shapes. The studies of this thesis were initiated with focus on the stainless steel nozzle-to-shell-can weld structures, a very typical structural configuration for pressure vessels used in petrochemical and nuclear power generation industries. Both the experimental and the FEA (finite element analysis), i.e. computational simulation, approaches were taken in the studies which addressed the influences of the welding fixture, the welding sequence, and the welding process on the distortion caused by stainless steel nozzle-to-shell welding. The investigations employed single and multi-nozzle weld test models (called mockups in the thesis) or FEA models. Manual GTAW (gas tungsten arc welding) and SMAW (shielded metal arc welding) processes were selected to represent the most common practice for stainless steel nozzle welding. The FEA simulations were conducted with ABAQUS program using sequentially coupled transient analysis method with lumped weld passes to achieve high computing efficiency. The investigations on the effect of the welding fixture concluded that the contour fixtures introduced in the thesis be effective for reducing the welding distortion for both the single and the multi-nozzle welding. The contour fixtures tend to localize the welding distortion, hence yield less impact on the global distortion of the whole weld structure. The rib-bar fixture, a more common fixture type for multi-nozzle welding, was found resulting in a big jump in the shell plate distortion when the fixture was removed. The studies on the influence of the welding sequence revealed that a progressive approach was more favorable for distortion control under the given nozzle-to-shell weld structure configurations. The best sequence suggested is to start welding at one nozzle, firstly on shell OD (outside diameter) side then on ID (inside diameter) side, then proceed to next neighboring nozzle. The effect of the welding direction of each weld pass was found affecting only the nozzle angular distortion. The experimental data showed that the manual GTAW process developed much higher shell plate distortion than the SMAW process. The reason would be that a higher percentage of the welding heat had been consumed on the base metal. The influence of the weld bead size didn???t appear to be significant. In the FEA study on the effect of the size of the lumped weld pass, the increase in weld bead size even resulted in a decrease in weld distortion. From the FEA simulation point of view, using large lumped pass would be a highly efficient choice without compromising too much in the precision of the distortion prediction. The FEA study confirmed that a decrease in cooling time after welding would result in more welding distortion. The large scale multi-nozzle mockup with rib-bar fixture demonstrated a maximum out-of-plane shell distortion of 16.4mm after the welding of 10 nozzles with GTAW+SMAW process, which suggests that additional measures should be developed to further control the welding distortion.