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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Stanovení pracovního rozsahu a účinnosti vodního trkače / Determination of the working range and efficiency of the water hammer pump

Růžička, Jakub January 2019 (has links)
This thesis focuses on setting the range and efficiency of a water ram pump through experimental measurements in a laboratory. The measurements were carried out on three different constructions of water ram pump, each of the designed and assembled by the author of this thesis himself, to find out whether the weight on the pulsating valve has an influence on the water ram pump efficiency. Further on this thesis aims at the comparison of up to now methods of water transport arrangement used at a summer camp and the usage of the water ram pump and its advantages. The principal of water ram pump originates in hydraulic impact that is being precisely described in a great detail as well. On of the chapters even includes the placement manual for the water ram pump and its overall assembly and connexion. Because the presence of floating debris is inevitable, this thesis also deals with the possibility to solve the incoming water impurities by adding an inflow gating to prevent such problem. This inflow gating has only been designed in a Flow 3D programme to introduce the idea and functions.
12

Studie pístového čerpadla s inversním kuličkovým šroubem a zatopeným motorem / Study of plunger pump with inverse ball screw and submersed motor

Švestka, Jiří January 2012 (has links)
This thesis is focused on study of piston pump with ball screw and submersed motor. Theoretic part is about study using pump and ball screw. Equations for description of pump, motor and ball screw are in computation part. And in last part is construction of pump and valve. Valve is computed in CFD.
13

Thermal and Fluidic Characterization of Tesla Valve Via Computational Fluid Dynamics

Porwal, Piyush 07 May 2016 (has links)
Tesla valve applications for passive flow enhancement in micro fluidic applications are promising, because of its design of no-moving-parts. The effectiveness of the valve (measured via its pressure and thermal diodicity) can be increased by creating a multi-staged Tesla valve. Present study investigates the effect of varying Reynolds number (25-200) on flow rectification and thermal enhancement capability of a Tesla valve. Gamboa Morris Forster (GMF) design with a cross-section of 1mm2 and constant valve-to-valve distance (1mm) was utilized for this research. An arbitrary fluid with constant properties at a reference temperature was used as the working fluid. Periodicity in flow and thermal distribution are noticed in the latter part of MSTV. Average friction factor and pressure diodicity decreased with increasing Reynolds number whereas average Nusselt number and thermal diodicity increased. Correlations for friction factor, pressure diodicity, Nusselt number, and thermal diodicity were derived by fitting a non-linear curve fit model.
14

Dynamická charakteristika zpětné armatury / The dynamic characteristics of check valve

Pavlík, Václav January 2016 (has links)
This master´s thesis provides an overview of all designs of check valves, their usage and typical features. Main purpose of this work is to clear up the phenomenon of check valve slam and the other problems that occur during transients. The check valve slam was measured at the test rig in the hydraulic laboratory. For unsteady flow evaluation after pump shut down was used Gibson method. The dynamic characteristic was possible to create by results from this method. It was achieved without impact of the speed of sound in the fluid. This work also contains 2D transient CFD calculations, which was used for evaluation of the hydrodynamic torque acting on the hinge pin. This approach provides an option to calculate wide range of cases at the expense of not entirely exact geometry. The main contribution of the theoretical study at the beginning of this thesis is its entireness. It might give an important clue when right valve is selecting. For good choice of valve might be helpful to use dynamic characteristics in this thesis presented. Mentioned characteristics were created by new way and its background is in measurements and simplified CFD calculations.
15

Měření dynamických charakteristik zpětných armatur / Measurement of dynamic characteristic of check valves

Novák, Jan January 2017 (has links)
Master thesis presents overview of existing types of check valves, their features, uses and issue called "cracking". Experimental part of this thesis focuses on the lift and swing check valves. Results of the measurement are evaluated from non-stationary flow point of view by developing and analyzing static and dynamic characteristics. This thesis takes into account losses and dynamic effects as main viewpoints. Two methods for measuring non-stationary velocities are used. Direct method called Gibson and indirect method laser doppler anemometry. Goal of the master thesis is to increase understanding of the check valves and their applicability.
16

Stanovení dynamických vlastností zpětného ventilu / Determination of check valve dynamic properties

Dolníček, Petr January 2017 (has links)
One of the objectives of the master´s thesis is to summarize types of most used check valves and their constructions. These check valves have specific static and dynamic properties. One of dynamic properties is vibration of closing member of lift check valve. Due to these vibrations, the added effects of fluid may result. This thesis deals with explanation and computation of these added effects.
17

Påldrivning: Jämförelse mellan luft- och vattendriven borrning : En utredning av jämförelser avseende slitage, logistik och driftkostnader

Bengtsson, Andreas, Bodin, Pierre January 2022 (has links)
Skanska Grundläggning in Region Special wishes to gain an increased understanding of the extent to which it differs in the wear of percussion hammers and pilot drill crowns, depending on which driving medium is used in down-the-hole drilling, as well as logistical and economic aspects depending on the chosen method. Down-the-hole drilling means that the hammer works down in the borehole and forms one of the components at the far end of the drill string together with a drill bit. The blow of the hammer is created by air or water at high pressure. The piling method that is examined is drilled steel pipe piles, which means that a steel pipe pile is driven into the ground in step with the hammer and the drill bit's advancement. Once the desired depth has been reached, the drill string with the drill bit is pulled out of the casing and then the steel pipe pile is filled with concrete. The study aims to examine the products' lifespans and repair intervals from several different perspectives and set them against reality, as well as what the different methods have for differences regarding logistics and establishment. This is to create a basis for future decisions on the most suitable method of down-the-hole drilling. The beginning of the study consisted of qualitative preliminary interviews to identify and create a problem formulation that was dealt with via a literature study, five semi-structured interviews, eleven questionnaires, internal data from drilling protocols and purchasing. The result shows that there is some difference in wear in the hammer depending on whether it is an air or water powered system, the wear appears in different places and can have an impact on the life of the hammer. The wear that occurs most frequently on drill bit is grinding on the buttons. Geotechnical differences for various projects are a significant factor in the service life of the equipment. An air hammer requires that the air constantly being mixed with lubricating oil and that an air compressor consumes more diesel compared to a high-pressure pump for the equivalent water hammer. The handling of water that is flushed out of the borehole is considered a concern. To reduce wear on water hammers and thus fewer replacements and more repairs, a drill bit intended for water powered down-the-hole hammer should be used. DTH-drilling with an air hammer is considered an industry standard and a certain skepticism towards a water powered system may indicate inexperience. / Skanska Grundläggning inom Region Special önskar att få en ökad förståelse hur vida det skiljer sig vid slitage av hammare och pilotborrkrona beroende på vilket drivande medium som nyttjas vid sänkhammarborrning, samt logistiska och ekonomiska aspekter beroende på vald metod. Sänkhammarborrning innebär att hammaren arbetar nere i borrhålet och utgör en av komponenterna längst ut på borrsträngen tillsammans med en borrkrona. Hammarens slag skapas av luft eller vatten i högt tryck. Pålningsmetoden som undersöks är borrade stålrörspålar, det betyder att ett foderrör drivs ned i marken i takt med hammaren och borrkronans framfart. Väl när önskat djup uppnåtts lyfts borrsträngen med hammaren och piloten upp ur foderröret för att sedan fyllas upp med betong. Studien syftar till att undersöka produkternas livslängder och reparationsintervall från flera olika perspektiv och ställa dem emot verkligheten, samt vad dem olika metoderna har för olikheter kring logistik och etablering. Detta är för att skapa underlag för framtida beslut om mest lämplig metod av sänkhammarborrning. Studiens begynnelse bestod av kvalitativa förintervjuer för att identifiera och skapa en problemformulering som avhandlades via en litteraturstudie, fem semistrukturerade intervjuer, elva frågeformulär, interna data från borrningsprotokoll och inköp. Resultatet visar att det förekommer viss skillnad i slitage i hammaren beroende på om det är en luft- eller vattenanläggning, slitaget visar sig på olika ställen och kan ha betydelse för hammarens livslängd. Det slitage som uppträder mest frekvent på piloter är nedslipning av stift. Geotekniska egenskaper för olika projekt utgör en betydande faktor för utrustningens livslängd. En lufthammare är i behov av att luften konstant beblandas smörjolja och att en luftkompressor förbrukar mer diesel jämfört med en högtryckspump för motsvarande vattenhammare. Efterhanteringen av vatten som spolas upp anses vara ett bekymmer. För att minska slitage på vattenhammare och därmed färre byten och mer reparationer bör en pilotborrkrona avsedd för vattendriven sänkhammarborrning nyttjas. Sänkhammarborrning med lufthammare anses som branschstandard och en viss skepticism mot en vattendriven anläggning kan tyda på oerfarenhet.

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