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Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna ; Bílek, V. ; Haidl, J. ; Isoz, Martin ; Pivokonský, M.
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
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Modelling the Oil Lubrication System of Turbocharger
Breckl, Lukáš ; Hliník, Juraj (referee) ; Novotný, Pavel (advisor)
The diploma thesis contains a research part focused on turbocharger construction, engine lubrication system and turbocharger, basic physical properties of lubricating oils and hydrodynamics. The purpose of this thesis is to create analytical and CFD computational model of turbocharger lubrication system. Output pressures and the loss of specific energy are determined.
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Design of modular tubular heat exchanger
Marx, Sven ; Turek, Vojtěch (referee) ; Jegla, Zdeněk (advisor)
Hlavním cílem této práce je seznámit se s požadavky specifické procesní aplikace a návrhem výměníku tepla s křížovým tokem pracovních látek a zhodnotit návrh předmětného výměníku pomocí simulačního softwaru. Nejprve jsou v práci prozkoumány provozní podmínky rekuperace odpadního tepla a obecné možnosti návrhu a jsou uvedeny základní rovnice pro tepelný a hydraulický výpočet. Hlavní část práce se zaměřuje na modulární trubkový výměník tepla s křížovým tokem pracovních látek navržený pro experimentální výzkum rekuperace tepla a zanášení ze znečištěných spalin produkovaných spalováním alternativních paliv na VUT v Brně (VUT) na Ústavu procesního inženýrství (UPI). Nejprve je stručně představena situace v testovací laboratoři. Poté je popsán postup návrhu předmětného tepelného výměníku pomocí softwaru HTRI a výsledky jsou shrnuty a porovnány s cílovými požadavky. Následně je analyzována distribuce toku vody v trubkovém prostoru uvnitř jednoho ze čtyř identických modulů výměníku tepla užitím softwaru CDF pomocí tří různých simulačních přístupů. Jsou popsány dva přístupy využívající model turbulence k--SST a jeden přístup využívající model turbulence k--Realizable turbulence. Nakonec jsou diskutovány rozdíly mezi přístupy a výsledky simulací distribuce toku.
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Simulation of air valves and difusers
Bombera, Jiří ; Rubinová, Olga (referee) ; Uher, Pavel (advisor)
The aim of the diploma thesis is the simulation of air valves and difusers using CFD. The goal of this thesis is to determinate the type of air valve and diffusor, which would ventilate the room of a detached house the best – considering the speed of the airflow and the age of the air. Outcome of this work is the design of the air conditioning system for a detached house with application of the air valve and difuser which is evaluated as the ideal option for the ventilation in the room.
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Inlet recirculation of centrifugal pump
Heinz, Pavel ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
This diploma thesis deals with the phenomenon appearing in hydrodynamic pumps at the sub-optimal flow rate. This phenomenon is inlet recirculation, which is an undesirable phenomenon in the suction of the pump. This recirculation causes cavitation, pressure pulsations and may cause clogging of the suction line. The main goal of the diploma thesis is CFD simulation for the recirculation mode, identification of the flow phenomena, and designs of possible measures to suppress inlet recirculation.
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Computational analysis of fluid flow in a tumble dryer
Dohnal, Miloslav ; Juřena, Tomáš (referee) ; Hájek, Jiří (advisor)
The aim of this work is to create a computational model of radial industrial tumble dryers, to calculate and identify the amount of air that flows through the inside of the drum itself. The calculation will be performed via computational fluid dynamics (CFD). Furthermore, compile transient balance model of mentioned dryers. Perform simulation balance model and compare the results of simulations with experimental measurements. By comparing the experimental data and simulation to determine the degrees of freedom of balance model and evaluate their impact on the assembled transient model. For a better understanding of the drying process, there is constructed a system of differential equations describing heat and moisture within the material being dried on a simple model. In the section devoted to the computational analysis of fluid flow is analyzed existing geometry of the drum, which has a major impact on the flow of air inside the drum itself. Following describes how to simplify its complex geometry entering the computational fluid dynamics. Then, there is carried out a simulation of fluid flow inside the tumble dryers using MRF and Sliding Mesh models. Finally, there is an analysis of the data obtained and determined the average amount of air flowing through the drum itself. On the contrary, the aim of the work is not to create another text tool for students engaged in CFD theme.
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