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Processing and analysis of HS videorecords of liquid atomization for a pressure-swirl nozzle
Červenec, Adam ; Lízal, František (referee) ; Jedelský, Jan (advisor)
This bachelor thesis deals with processes of liquid atomization for a pressure-swirl nozzle. The main goal was to study liquid cone, which is gradually fragmenting on smaller parts ending in creating small droplets. It was needed to study theory of liquid flow, motion of droplets and an impact of the geometry of nozzle. When the theoretical part ended we could perform an experiment, which consists of preparing devices and creating own video records using highspeed camera Photron FASTCAM SA-Z. The camera provided us detailed view on the spray and events, for example collisions of droplets, which are the main subject of this thesis. Afterwards the video records were analyzed and we could provide results connected with studied problem.
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Injection systems of rocket engines
Vrbica, Kryštof ; Cejpek, Ondřej (referee) ; Malý, Milan (advisor)
This bachelor thesis deals with liquid propelled rocket engine injector design. The theoretical part describes the categorisation and principles of the function of a rocket injector element. The following research part provides an in-depth examination of the most often used injectors including their possible versions. This section concerns coaxial, pintle and impinging injectors. The emphasis is laid on discharge coefficient, spray behaviour and definition of the optimal injector geometry for high-quality atomization. The thesis is concluded with a design of test injectors and their experimental comparison. Coaxial and two version of impinging injector are tested with regards to spray behaviour, their discharge coefficients, Sauter mean diameter and droplet velocity. Design drafts required for production are included in this thesis.
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Injection systems of rocket engines
Vrbica, Kryštof ; Cejpek, Ondřej (referee) ; Malý, Milan (advisor)
This bachelor thesis deals with liquid propelled rocket engine injector design. The theoretical part describes the categorisation and principles of the function of a rocket injector element. The following research part provides an in-depth examination of the most often used injectors including their possible versions. This section concerns coaxial, pintle and impinging injectors. The emphasis is laid on discharge coefficient, spray behaviour and definition of the optimal injector geometry for high-quality atomization. The thesis is concluded with a design of test injectors and their experimental comparison. Coaxial and two version of impinging injector are tested with regards to spray behaviour, their discharge coefficients, Sauter mean diameter and droplet velocity. Design drafts required for production are included in this thesis.
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Internal Flow of Spill-Return Pressure-Swirl Atomizers
Malý, Milan ; Honus,, Stanislav (referee) ; Lozano, Antonio (referee) ; Jedelský, Jan (advisor)
Tlakové vířivé trysky (TVT) jsou používané v mnoha aplikacích, kde je potřebná velká plocha kapek nebo kde povrch musí být nanesen kapalinou, např. spalování, sprejové chlazení nebo nanášení barev. Parametry spreje z TVT jsou úzce spojené s jejich vnitřním prouděním. Obtokové trysky vylepšují koncepci klasických TVT přítomností otvoru, skrz který může kapalina odtékat zpět do nádrže. Díky této koncepci je možné regulovat vstřikovací množství kapaliny změnou průtoku tímto otvorem, zatímco se ve vířivé komůrce udržuje vysoký tlak, který zaručí dobrou kvalitu spreje. Obtokové trysky byly historicky málo prozkoumány a jejich vnitřní proudění nebylo studováno téměř vůbec. V této práci je popsáno vnitřní proudění několika obtokových trysek jak experimentálně, tak numericky. Tato data jsou následně korelována s měřenými vlastnostmi spreje. Výsledky ukazují, že přidání obtokového otvoru silně ovlivní vnitřní proudění i v případech, kdy obtokem neproudí žádná kapalina. V některých případech se vůbec nezformuje vzdušné jádro a tím se destabilizuje výtok z trysky, čímž vznikne nestabilní sprej. Mimoosé obtokové otvory generují a stabilizují vzdušné jádro, což pomáhá formovat kapalinovou stěnu a vysoce kvalitní sprej. Nicméně některé konfigurace změnily charakter rozpadu kapalinové stěny, což se projevilo i na kvalitě spreje. Navíc regulační schopnost a stabilita spreje závisí na vzdálenosti obtokových otvorů od osy vířivé komůrky. Na závěr byla upravena neviskózní teorie, která analyticky popisuje vnitřní proudění v TVT, tak aby byla aplikovatelná i na obtokové trysky. Pomocí tohoto přístupu byla odvozena teoretická predikce výtokového součinitele a velikosti vzdušného jádra v závislosti na obtokovém poměru (SFR). Zároveň byly pro obtokové trysky upraveny empirické korelace původně odvozené pro TVT. Tato práce přináší nový vhled k porozumění vnitřního proudění obtokových trysek a její výsledky najdou uplatnění při jejich návrhu.
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Testing of a transparent model of a pressure-swirl nozzle
Sapík, Marcel ; Pech, Ondřej (referee) ; Jedelský, Jan (advisor)
The aim of the thesis is to put a transparent scaled PMMA model of the pressure swirl nozzle into operation, which includes, the selection of working fluids and the preparation of a test set to allow measurements using optical methods (LDA, PDA, PIV, high-speed visualization). The theoretical part describes the basic theory of atomization, optical measurement methods and deals with the problems of optical transition in optically complex systems. It also includes an extensive search for transparent liquids and materials of enlarged models that have been used in experiments, which often aim to match light refractive indices between these materials. In the practical part, attention is paid to the preparation of the test set and tests of chemical effects of several selected liquids on PMMA material are conducted, including a summary of experience with their use, as there was a permanent damage to the material. Several LDA measurements followed, using kerosene, p-cymene, 1-bromonaphthalene and water, evaluated the effect of the refractive index difference on the results. It turned out that no observable influence occurred if the refractive index difference between the nozzle material and the liquid was small. In addition, a visualization of internal flow through a high-speed camera was made. The practical part closes the static pressure measurement in the nozzle chamber, where the pressure ratio was measured on the walls of the chamber as well as on its axis. The measurement confirmed that the pressure on the chamber walls is constant and varies with the distance from the chamber axis.
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Experimental Analysis of the Liquid Breakup Process of an Effervescent Atomizer
Zaremba, Matouš ; Hyhlík, Tomáš (referee) ; Hájek, Jiří (referee) ; Jedelský, Jan (advisor)
The thesis deals with experimental research of mechanism of liquid breakup at twin-fluid atomizers. Four different atomizers were examined at the beginning of the research. Two of them were of standard design (Y-jet and effervescent nozzles), and the rest two atomizers were developed as a part of the thesis (so called CFT and inversed effervescent atomizers). Results show that only the inversed effervescent atomizer was capable of generating stable spray under examined conditions due to the specific breakup mechanism. This mechanism is similar to what was observed in effervescent atomizers. However, the mixing process inside the inversed effervescent atomizer is very different. The specific breakup mechanism was then defined as the main scope of the thesis. It was investigated by the high-speed imaging. The images were then processed by proper orthogonal decomposition and by fast Fourier transformation. Spray spatial development was examined using phase Doppler anemometer. The data was analyzed to describe the dynamics of the spray. A detailed description of the breakup mechanism is made from the combination of the experimental and post-processing techniques. The thesis brings new insight into the understanding of the liquid breakup mechanism and shows a potential for a further development of the inversed effervescent atomizer.
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Processing and analysis of HS videorecords of liquid atomization for a pressure-swirl nozzle
Červenec, Adam ; Lízal, František (referee) ; Jedelský, Jan (advisor)
This bachelor thesis deals with processes of liquid atomization for a pressure-swirl nozzle. The main goal was to study liquid cone, which is gradually fragmenting on smaller parts ending in creating small droplets. It was needed to study theory of liquid flow, motion of droplets and an impact of the geometry of nozzle. When the theoretical part ended we could perform an experiment, which consists of preparing devices and creating own video records using highspeed camera Photron FASTCAM SA-Z. The camera provided us detailed view on the spray and events, for example collisions of droplets, which are the main subject of this thesis. Afterwards the video records were analyzed and we could provide results connected with studied problem.
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Experimental study of spray characteristics and functionality of small pressure-swirl atomizers
Malý, Milan ; Lízal, František (referee) ; Jedelský, Jan (advisor)
Diplomová práce se zabývá experimentální studií vlastností spreje z několika malých tlakových vířivých trysek používaných ve spalovacích komorách proudových motorů. Po desetiletí byla snaha zlepšit jejich rozprašovací charakteristiky a stále jsou možnosti, které nebyly téměř prozkoumány. Výzkum byl proveden za použití různých geometrií jednotlivých dílů trysky za účelem zjištění jejich vlivu na sprej. Byl použit různý počet vstupních portů (2, 3 a 4), různé vířivé komůrky (kulová, kuželová, konvexní, nízká kuželová) a rozdílné návrhy obtokového otvoru (osové, mimosové). Důraz byl kladen na posouzení stability spreje, kde pulzující sprej negativně ovlivňuje provozní charakteristiky spalovací komory. Vlastnosti spreje byly proměřeny fázovým dopplerovským analyzátorem, cirkulární homogenita byla hodnocena mechanickým paternátorem a rozpad kapaliny byl vizualizován pomocí jednoduchého laserového stínografu.
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Design and construction of transparent nozzle for visualization and measurement of the internal flow
Sapík, Marcel ; Fojtlín, Miloš (referee) ; Jedelský, Jan (advisor)
This thesis deals with design and construction of transparent nozzle for research of internal flow of liquids. The objective was to design potential construction of the nozzle and make a manufacturing drawing. The theoretical part deals with basics of atomization including properties of liquids and describes basic optical methods for internal flow in a nozzle. In the research part of this thesis, a number of construction solutions has been picked to serve as an inspiration for the final shape of the nozzle. Its construction is elaborated in the last part along with a description of the process, a manufacturing drawing, and a visual documentation with a 3D model.
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Estimation of spray cone angle from atomization nozzles using image based methods
Štafa, Ondřej ; Pech, Ondřej (referee) ; Jedelský, Jan (advisor)
The aim of the bachelor thesis is to estimate spray cone angle. The theoretical part deals with basic principles of atomization, spray structure and spray processing methods including image based methods. The experimental part describes steps of spray cone angle estimation in several specially designed softwares. Advantages and disadvantages of these programmes were evaluated with great emphasis on functionality. Results contain data of spray cone angle values depending on distance between atomization nozzle and spray stream level.
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