This thesis deals with the experimental and numerical analysis of the water hammer phenomenon generated by the discharge of a pressurized liquid into a pipeline kept under vacuum conditions. This flow configuration induces several multiphase phenomena such as cavitation and gas desorption that cannot be ignored in the water hammer behavior.<p><p>The motivation of this research work comes from the liquid propulsion systems used in spacecrafts, which can undergo fluid hammer effects threatening the system integrity. Fluid hammer can be particularly adverse during the priming phase, which involves the fast opening of an isolation valve to fill the system with liquid propellant. Due to the initial vacuum conditions in the pipeline system, the water hammer taking place during priming may involve multiphase phenomena, such as cavitation and desorption of a non-<p>condensable gas, which may affect the pressure surges produced in the lines. Even though this flow behavior is known, only few studies model the spacecraft hardware configuration, and a proper characterization of the two-phase flow is still missing. The creation of a reliable database and the physical understanding of the water hammer behavior in propulsion systems are mandatory to improve the physical models implemented in the numerical codes used to simulate this flow configuration.<p><p>For that purpose, an experimental facility modeling a spacecraft propulsion system has been designed, in which the physical phenomena taking place during priming are generated under controlled conditions in the laboratory using inert fluids. An extended experimental campaign was performed on the installation, aiming at analyzing the effect of various working parameters on the fluid hammer behavior, such as the initial pressure in the line, liquid saturation with the pressurant gas, liquid properties and pipe configuration. The influence of the desorbed gas during water hammer occurrence is found to have a great importance on the whole process, due to the added compressibility and lower speed of sound by an increasing amount of non-condensable gas in the liquid + gas mixture. This results in lower pressure levels and faster pressure peaks attenuation, compared to fluids without desorption. The two-phase flow was characterized by means of flow visualization of the liquid front at the location where the fluid hammer is generated. The front arrival was found to be preceded by a foamy mixture of liquid, vapor and non-condensable gas, and the pressure wave reflected at the tank may induce the liquid column separation at the bottom end. While column separation takes place, the successive pressure peaks are generated by the impact of the column back against the bottom end.<p><p>The resulting experimental database is then confronted to the predictions of the 1D numerical code EcosimPro/ESPSS used to assess the propulsion system designs. Simulations are performed with the flow configuration described before, modeling the experimental facility. The comparison of the numerical results against the experimental data shows that aspects such as speed of sound computation with a dissolved gas and friction modeling need to be improved. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

This master thesis treats the modelling of a common-rail direct fuel injection system where pressure generation is decoupled from the injection process. It has been shown that the fuel pressure plays a vital role for the general performance of the engine, affecting both emissions and efficiency, and it is carefully regulated to achieve optimal performance at different operating points. In an attempt to facilitate the development of the responsible control algorithms, a simulation framework has been requested. A model describing the complete work cycle of the high-pressure fuel system is developed and implemented in a Simulink environment. It is to a large extent based on the underlying physics and constructed in a modular manner, which allows for different engine configurations to be simulated. The modelled pressure signal is compared to experimental data at different operating points with promising results in capturing the transient behaviour from a low-level perspective. Additionally, it manages to replicate some of the pressure oscillations which has been observed in the real system and it shows good response to changes in the input signals. However, there are some areas which are subject to improvement since capturing the static pressure levels over longer drive cycles has proved to be a difficult task. Overall, the developed model serves as a starting point for future development and validation of control algorithms.

Blockfields as an indicator of landscape development with a specific microclimate is presented in many scientific publications. This diploma thesis is focused on finding the relationship between the hardness of stone blocks and the intake of potential radiation, with an assessment of morphology, location and local conditions. Within the selected study areas in Northern Bohemia was recorded a total of 73 blockfields, of which 22 sites were selected for further investigation. From the results of the statistical analyses was shown the relationship between the income potential of radiation and the degree of ventilation of stone blocks. The analyses also show the relationship between the hardness of stone blocks in the blockfields and the orientation of the blockfields to the world's sides, which proved to be significant. The tests performed by the analyses of each third (high) stone seas have shown the possibility of moving rock blocks downhill.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Neste trabalho foram realizadas simulaÃÃes do transiente hidrÃulico com vÃlvula antecipadora de onda com abertura e fechamento completo e nÃo instantÃneo, como mecanismo de alÃvio para o golpe de arÃete. A vÃlvula deve situar-se prÃximo ao conjunto motor-bomba. Assim, a vÃlvula antecipadora serà aplicada ao segundo nà das adutoras consideradas, utilizando-se para o cÃlculo o software UFC6, produzido no Grupo de Estudos em HidrÃulica Computacional da Universidade Federal do CearÃ. A vÃlvula antecipadora de onda inicia sua abertura quando a pressÃo mÃnima de regulagem à excedida, logo apÃs a passagem da onda de baixa pressÃo. O fluido expulso deve ser disposto em um manancial, ou armazenado em um reservatÃrio que comporte todo esse volume. Neste trabalho, a vÃlvula antecipadora de onda à modelada utilizando a Ãgua como fluido. O fluido (Ãgua) à expulso segundo um modelo de descarga com pressÃo externa atmosfÃrica. As simulaÃÃes aqui descritas utilizam o mÃtodo das caracterÃsticas. Devido à falta de estudos nessa Ãrea, este trabalho visa contribuir para o dimensionamento de vÃlvulas antecipadora de onda e servir como base para trabalhos subsequentes. / In this work was made Hydraulic Transient simulations with anticipation valve with opening and closing complete and non-instantaneous, as a mechanism of relief for water hammer. The valve must be located near the pump. Thus in this work, the valve in advance shall be applied to the second node of the pipelines in question. The software UFC6 was used for estimates the Transient and was produced by the Study Group on Computational Fluid of UFC. Anticipation is a mechanism for relief from water hammer that starts opening when the low pressure of regulation is exceeded, after the passage of the wave of low pressure. The fluid expelled must be placed on a spring or stored in a reservoir in order to accommodate the volume of fluid to be expelled. In this work, the Anticipation Valve is modeling into the water as a fluid. It uses the method of characteristics for simulations. Due to the lack of studies in this area, this research aims to contribute to the design of anticipation valves and a basis for further work.

Waterhammer is an undesirable event, caused by sudden flow changes in a confined pipe system. When it occurs, its consequences can be very costly and even sometimes deadly. In general, it may be encountered in the penstocks of hydropower plants, water transmission lines, water networks, etc. Therefore, the operation guidelines of the hydropower plants should be defined correctly. In this thesis, waterhammer problems in pumped storage hydropower plants are investigated. Time dependent flow conditions in the penstocks are studied by the help of computer software, HAMMER. The software solves nonlinear differential equations by using method of characteristics. Firstly, hydraulic transients for various operational cases are investigated using some scenarios. Then a surge tank, protective device for waterhammer, is added to the system and for the same operational cases, hydraulic transients are studied again. Finally, the results obtained from the operation of the system with and without surge tank are compared. Wind-hydro hybrid systems are also included in the study.

Submitted by Franciane Falcão (francifalcao@gmail.com) on 2017-09-05T21:54:06Z No. of bitstreams: 1 PPGDesign_UNESP-FAAC_Tese_FranFalcao_FINAL.pdf: 39549375 bytes, checksum: 22f12a9192fb70de587874aa2242701e (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-09-06T16:43:08Z (GMT) No. of bitstreams: 1 falcao_fs_dr_bauru.pdf: 39549375 bytes, checksum: 22f12a9192fb70de587874aa2242701e (MD5) / Made available in DSpace on 2017-09-06T16:43:08Z (GMT). No. of bitstreams: 1 falcao_fs_dr_bauru.pdf: 39549375 bytes, checksum: 22f12a9192fb70de587874aa2242701e (MD5) Previous issue date: 2015-05-29 / Fundação de Amparo à Pesquisa do Estado do Amazonas (FAPEAM) / Pesquisas na área do design ergonômico têm delineado parâmetros para o desenvolvimento de diversos produtos, por meio do estudo da relação de aspectos formais de produtos e a percepção ou solicitações físicas humanas. Entretanto, estudos da correlação de aspectos formais da superfície de contato (texturas das interfaces) com a percepção humana no uso de ferramentas manuais apresentam-se ainda incipientes. Este estudo teve por objetivo avaliar a relação de três características formais de textura (disposição, densidade gráfica, profundidade) com a percepção de desconforto e agradabilidade, visando compreender o dimensionamento sensorial tátil em ferramentas manuais. Para tanto, foi aplicado a fase de avaliação do método SEQUAM, com uso de 8 mock-ups de martelos unha com distintas configurações de texturas aplicadas aos seus cabos. As simulações de uso foram realizadas com profissionais de marcenaria (PM) e usuários domésticos (UD). Os resultados desta abordagem experimental demonstraram que as características de disposição, densidade gráfica e profundidade interferem na percepção do usuário; e que entre estas três características a densidade gráfica das ranhuras apresentou um número maior de aspectos perceptíveis com diferenças significativas (p<0,05) entre os mock-ups. Outro dado expressivo foi a diferença de percepção entre os grupos de sujeitos PM e UD. Estes resultados caracterizam as texturas das superfícies de contato de ferramentas manuais como elementos formais associados a certas percepções obtidas no uso do produto; e aponta possíveis contribuições de estudos sobre dimensionamento sensorial tátil para o design ergonômico de ferramentas manuais. / Researches in the area of ergonomic design have outlined parameters for the development of several products, through the study of the relationship of formal aspects of products and the perception or human physical requests. However, studies of the correlation of formal aspects of the contact surface (interfaces textures) with human perception in the use of hand tools are still incipient. The aim of this study was to evaluate the relationship of three formal characteristics of texture (layout, graphic density, depth) with the perception of discomfort and pleasantness, in order to understand the tactile sensorial dimensioning in hand tools. Therefore, the evaluation phase of the method SEQUAM, with use of 8 mock-ups of nail hammers with distinct texture configurations applied to their cables. The use simulations were performed with carpentry professionals and home users. The results of this experimental approach demonstrated that the characteristics of layout, graphic density and depth interfere in the perception of the user; and that among these three characteristics the graphical density of the grooves presented a greater number of perceptible aspects with significant differences (p <0.05) between the mock-ups. Another expressive data was the difference of perception between the groups of subjects, carpentry professionals and home users. These results characterize the textures of contact surfaces of hand tools as formal elements associated with certain perceptions obtained in the use of the product; and points out possible contributions of studies on tactile sensorial dimensioning for the ergonomic design of hand tools. / FAPEAM: 2800/2011

TICHÝ Pavel: Production of a holder body by solid forming. A Graduation Thesis of Master´s Studies, the 5th Year of Study, the School-year 2008/2009, FSI VUT Brno, Department of Machining, May 2009, Pages No. 80, Appendixes No. 9. The Graduation Thesis, elaborated in the framework of engineering studies, presents the technology of a body holder production carried out by solid forming. The material of the forged piece is steel Ck55 (12 060), the semi-finished product is of the 65 and its length is 12m. A yearly production is 122 000 pieces. Based on the studies of possible production technologies, the technology of production by die forging has been chosen, while a drop forging technology on a hammer HO630 and product-trim on a trimming press S160 have been used. For this option, the required technological calculations, the design of the die, the specification of production machines, which are necessary for forging process realization, have been carried out. An inspection of the propose forging by a private forge and a change in the geometry of the die have been carried out. A part of the study is a simulation forming process which is made in the software QFORM.

Vibration compaction is the most effective way of compacting coarse-grained materials. The effects of vibration frequency and amplitude on the compaction density of different backfill materials (No. 4 natural sand, No. 24 stone sand and No. 5, No. 8, No. 43 aggregates), were studied in this research. The test materials were characterized based on the particle sizes and morphology parameters using digital image analysis technique. Small-scale laboratory compaction tests were carried out with variable frequency and amplitude of vibrations using vibratory hammer and vibratory table. The results show an increase in density with the increase in amplitude and frequency of vibration. However, the increase in density with the increase in amplitude of vibration is more pronounced for the coarse aggregates than for the sands. A comparison of the maximum dry densities of different test materials shows that the dry densities obtained after compaction using the vibratory hammer are greater than those obtained after compaction using the vibratory table at the highest amplitude and frequency of vibration available in both equipment. Large-scale vibratory roller compaction tests were performed in the field for No. 30 backfill soil to observe the effect of vibration frequency and number of passes on the compaction density. Accelerometer sensors were attached to the roller drum (Caterpillar, model CS56B) to measure the frequency of vibration for the two different vibration settings available to the roller. For this roller and soil tested, the results show that the higher vibration setting is more effective. Direct shear tests and direct interface shear tests were performed to study the impact of particle characteristics of the coarse-grained backfill materials on interface shear resistance. A unique relationship was found between the normalized surface roughness and the ratio of critical-state interface friction angle between sand-gravel mixture with steel to the internal critical-state friction angle of the sand-gravel mixture.

Elevation, longitudinal profile, and Schmidt hammer data indicate that strath terraces (specifically the lower elevation terraces) mapped in the Fremont River drainage of Capitol Reef National Park are correlative to the terraces of the smaller Pleasant Creek drainage located approximately ten miles to the south. This correlation suggests that drainage development in this area of the Colorado Plateau was strongly dependent upon a regional-scale forcing mechanism (e.g. climate) rather than strictly independent basin-scale processes. Elevations of mapped strath terraces and their associated black volcanic boulder deposits were calculated from geologic maps, Digital Elevation Models (DEM), and Digital Orthophoto Quadrangles of the Fruita and Golden Throne Quadrangles, Wayne and Garfield Counties, Utah. Terraces in both drainages were placed into twenty foot elevation bins and then gathered into larger terrace levels based upon population breaks and the degree of weathering as seen from Schmidt hammer hardness data. Comparison of the two datasets indicate that the two lowest terrace levels of the Fremont River compare well with the two terrace levels of Pleasant Creek both in elevation above the present stream bed and in Schmidt hammer hardness measurements. Our data demonstrate that the Fremont River drainage is likely much older than the smaller Pleasant Creek drainage. Further, correlative terrace data strongly suggests that glacial-interglacial climate forcing played a dominant role in the landscape evolution of both drainages and by inference, the broader Colorado Plateau. Terrace elevation data were compared with recently published cosmogenic ages for several terrace deposits located within the Fremont River drainage. This comparison provides compelling evidence that highest concentrations of preserved terraces may be time correlative with discrete isotopic stages associated with glacial maximum and/or deglacial conditions. Finally, our data also demonstrate that in this area of the Colorado Plateau incision rates are on the order of ~60 to 85 cm/ka, which is on the high end of reported rates from other researchers.

Top hammer drilling uses a percussive force at the top combined with a rotational energy that transmits through a rod to a drill bit that crushes rock. It is a drilling method that is preliminary used in mining, construction and operations under ground. Fatigue strength plays an important role in the drill rods life span. A top hammer drill rod has a through hole in the center called a flush hole used to flush up the drilling cuttings. The flush hole is a weak spot in the rod. In this preliminary study the purpose was to investigate if, and how, the surface in the flush hole affects the fatigue strength in rock drill rods. Four test methods; Refined inner surface, lathed core, without lubricant and sealed hollow bar. With three samples of each method that affected the surface of the flush hole, were used in the manufacturing of the rods and compared to references. Different tests were applied to measure the quality of the flush hole and of the rods. The material used were fatigue tested under a pulsating pull-pull condition with flushing water. Finally, the fracture surfaces were studied. The fatigue test showed that refined inner surface had supreme fatigue strength, the other methods exhibit approximately 10% more cycles than the references. In conclusion the inner surface affects the fatigue strength. The parameter with the most distinct correlation to the fatigue test was surface roughness. Other parameters that seems to affect were oxidation, hardness and scratches. To obtain statistical certainty more samples are needed.