The diploma thesis titled, Computational model of shock absorber, is concerned with ways to simulate individual actuators of dampening with the goal of obtaining F-v characteristics dependent on the setup of the shock absorber. The work is divided into two halves, the first one being a review of literature and the second half being practical. The review part is focused on ways of shock absorber constructions and the physical principles involved with the present forces. The practical part of the work contains a computational model of a monotube shock absorber in the Matlab programming software.

The master thesis deals with the replacement of heat exchanger surfaces during simulations in the ANSYS Fluent. The aim of this work is to find a simplified model of the heat exchanger usable for flow simulations in large process and energy units, where it is not possible to model the entire heat exchanger in detail. The calculation procedures are applied to „tube bank” heat exchanger. The master thesis is divided into three parts. First part deals with pressure losses. The "porous zone" approach is used as a replacement for the heat exchanger surface. In the second part, the heat transfer by convection and conduction through the heat exchanger is replaced by the "Heat Exchanger" module. The third part examines the influence of material properties, heat source and fixed temperatures on incident radiation. All calculations resulting from the methods are performed using a script that prepares the output data in format suitable for insertion into ANSYS Fluent. A simplification, which faithfully replaces a fully modeled heat exchanger, has been found in all three parts of the thesis.

This master’s thesis deals with the simulation of flow through the normalized orifice plate. There is described flow measurement with flowmeters, which reduces the cross-section of the pipe and causes the pressure difference before and after the flowmeter. Following is a description methods of modeling of turbulent flow and a description of software for the simulation of flow from the company Ansys. The theoretical part is followed a practical part, which is focused on determining the permanent pressure loss caused by the orifice plate and the verification of straight pipeline lengths between orifice and obstacle.

This diploma thesis deals with a design of a boiler for stillage combustion. Stoichiometric calculations and enthalpies of combustion gases have been calculated from the specified parameters. In addition, heat calculation, design of the combustion chamber dimensions and dimensioning of heat surfaces were accomplished. The boiler has an evaporator with natural circulation and a fire grate.

The present thesis deals with a design of a heating system for reconstructed family house. The heat loss was calculated according to ČSN EN 12831 Heating systems in buildings – Method for calculation of the heating load. The projected system was regulated. Hot water generation and the safety devices, such as safety valve or expansion tank, were designed. The total costs were calculated afterwards.

This master thesis has two goals: First is to design a Permit Set of Drawings for a combined building of studios, classrooms and theather hall with neccesary auxilary facilities in Brno. Building is detached, five-storey with a basement. In the basement there are garages, theather hall with with facilities and HVAC technologies. The load-bearing structure is prefabricated reinforced concrete frame with ceramic masonry envelope and partitions. Roof is designed as a flat green roof. Building should fulfil the passivhaus requirements. The second goal of the thesis is to assess and compare common metal-based air-conditioning tubing with system based on stone-wool materials called CLIMAVER. The assessment and comparison is based on experimental measurements of the systems’ pressure losses.

Highly loaded single stage gas turbines are being developed to minimize the turbine size and weight. Such highly loaded turbines often result in transonic flows, which imply a reduction in the efficiency due to the shock losses. The efficiency of a turbine is defined as the ratio between the real work extracted by the turbine rotor from the fluid and the maximum available enthalpy for a given pressure ratio. The relationship between turbine performance and design parameters is not yet fully comprehended due to the complexity of the flow field and unsteady flow field interactions. Hence, experimental and numerical studies remain necessary to understand the flow behavior at different conditions to advance the state of the art of the prediction tools. The purpose of the current research is to develop a methodology to determine the efficiency with an accuracy better than 1 % in a cooled and uncooled high pressure (HP) turbine tested in a short duration facility with a running time of about 0.4s. Such low level of uncertainty requires the accurate evaluation of a large number of quantities simultaneously, namely the mass flow of the mainstream, the coolant, and leakage flows properties, the inlet total pressure and total temperature, the stage exit total pressure, the shaft power, the mechanical losses and the heat transfer. The experimental work is carried out in a compression tube facility that allows testing the turbine at the temperature ratios, Re and Mach numbers encountered in real engines. The stage mass flow is controlled by a variable sonic throat located downstream of the stage exit. Due to the absence of any brake, the turbine power is converted into rotor acceleration. The accurate measurement of this acceleration as well as those of the inertia and the rotational speed provides the shaft power. The inertia of the whole rotating assembly was accurately determined by accelerating and decelerating the shaft with a known energy. The mass-flow is derived from the measured turbine inlet total pressure and the vane sonic throat. The turbine sonic throat was evaluated based on a zero-dimensional model of the turbine. The efficiencies of two transonic turbines are measured at design and off-design conditions. The turbine design efficiency is obtained as 91.8 %. The repeatability of the measurements for 95% confidence level varies between 0.3 % and 1.1 % of the efficiency depending on the test case. The theoretical uncertainty level of 1.2 % is mainly affected by the uncertainty of exit total pressure measurements. Additionally, the effect of vane trailing edge shock formations and their interactions with the rotor blade are analyzed based on the experimental data, the numerical tools and the loss correlations. The changes of blade and vane performances are measured at mid-span for three different pressure ratios which influence the vane and rotor shock mechanisms. Moreover, the unsteady forces on the rotor blades and the rotor disk were calculated by integration of the unsteady static pressure field on the rotor surface.

This study aims to investigate hydraulics and the flow characteristics of drilling fluids inside annulus and to understand the mechanism of cuttings transport in horizontal and deviated wellbores. For this purpose, initially, extensive experimental studies have been conducted at Middle East Technical University, Petroleum &amp / Natural Gas Engineering Flow Loop using water and numerous drilling fluids for hole inclinations from horizontal to 60 degrees, flow velocities from 0.64 m/s to 3.05 m/s, rate of penetrations from 0.00127 to 0.0038 m/s, and pipe rotations from 0 to 120 rpm. Pressure loss within the test section and stationary and/or moving bed thickness are recorded. New friction factor charts and correlations as a function of Reynolds number and cuttings bed thickness with the presence of pipe rotation for water and drilling fluids in horizontal and deviated wellbores are developed by using experimental data. Meanwhile empirical correlations that can be used easily at the field are proposed for predicting stationary bed thickness and frictional pressure loss using dimensional analysis and the effect of the drilling parameters on hole cleaning is discussed. It has been observed that, the major variable influencing cuttings transport is fluid velocity. Moreover, pipe rotation drastically decreases the critical fluid velocity that is required to prevent the stationary cuttings bed development, especially if the pipe is making an orbital motion. A decrease in the pressure loss is observed due to the bed erosion while rotating the pipe. Cuttings transport in horizontal annulus is modeled using a CFD software for different fluid velocities, pipe rotation speeds and rate of penetrations. The CFD model is verified by using cuttings transport experiments. A mathematical model is also proposed to predict the flow characteristics of Newtonian fluids in concentric horizontal annulus with drillpipe rotation. The Navier-Stokes equations of turbulent flow are numerically solved using finite differences technique. A computer code is developed in Matlab 2007b for the proposed model. The performance of the proposed model is compared with the experimental data which were available in the literature and gathered at METU-PETE Flow Loop as well as Computational Fluids Dynamics (CFD) software. The results showed that the mechanistic model accurately predicts the frictional pressure loss and the velocity profile inside the annuli. The model&rsquo / s frictional pressure loss estimations are within an error range of &plusmn / 10%.

iv The primary objective of this study is to understand the mechanism, the hydraulics and the characteristics, of the two-phase flow in horizontal annuli. While achieving this goal, both theoretical and experimental works have been conducted extensively. The METU-PETE-CTMFL (Middle East Technical University, Petroleum and Natural Gas Engineering Department, Cuttings Transport and Multiphase Flow Laboratory) multiphase flow loop consists of 4.84 m long eccentric horizontal acrylic pipes having 0.1143m inner diameter (I.D) acrylic casing - 0.0571m outer diameter (O.D) drillpipe and 0.0932m I.D acrylic casing - 0.0488m O.D drillipipe geometric configurations. During each experiment, differential pressure loss data obtained from digital and analog pressure transmitters at a given liquid and gas flow rate were recorded. The flow patterns were identified visually. Meanwhile a mechanistic model has been developed. The flow pattern identification criteria proposed originally for twophase flow through pipes by Taitel and Dukler1 has been inherited and modified for the eccentric annular geometry. The complex geometry of eccentric annuli has been represented by a new single diameter definition, namely representative diameter dr. The representative diameter has been used while calculating the pressure losses. A computer code based on the algorithm of the proposed mechanistic model has been developed in Matlab 7.0.4. Both the flow pattern prediction and the frictional pressure loss estimation are compared with the gathered experimental data. Moreover, friction factor correlations have been developed for each flow pattern using experimental data and statistical methods. The performance of the proposed model and the friction factor correlations has been evaluated from experimental data. The mechanistic model developed in this study accurately predicts flow pattern transitions and frictional pressure losses. The model&rsquo / s pressure loss estimations are within &plusmn / 30% for two different annular flow geometries.

Les instabilités thermo-acoustiques se rencontrent fréquemment au sein des chambres de combustion de toute taille, de la petite chaudière au moteur de fusée. Ces instabilités sont causées par le couplage entre ondes acoustiques et dégagement de chaleur instationnaire. En effet, le passage d'une onde acoustique au travers d'une flamme va moduler son dégagement de chaleur qui, en retour, va générer de nouvelles ondes acoustiques. Lorsqu'une chambre de combustion entre en instabilité, d'importantes variations de pression sont observées ; ces fluctuations peuvent user prématurément le système ou altérer ses performances. L'étude des instabilités thermo-acoustiques a pour but d'améliorer notre compréhension de ces phénomènes complexes afin de les prévenir. L'objectif de ce travail est d'obtenir et d'intégrer au sein de modèles réduits des descriptions précises de la dissipation acoustique – effet stabilisant - et d'interaction flamme/acoustique – effet déstabilisant. Cette étude se décompose en trois axes : La première partie développe le concept de « modèle acoustique réduit » qui permet de prédire les modes acoustiques d'une chambre de combustion. Pour cela, sont prises en compte les dissipations inhérentes à certaines pièces(diaphragmes, injecteurs, ...) ainsi que le couplage flamme/acoustique. Une fois le modèle établi, il convient d'en chercher les solutions à l'aide d'un solveur numérique spécialement conçu pour cette tâche. Dans une deuxième partie, un banc expérimental est utilisé pour caractériser le lien entre perte de charge et dissipation acoustique. Il est montré de manière théorique et expérimentale que la connaissance des pertes de charge au travers d'un élément permet de prédire son comportement acoustique à basse fréquence. La dernière partie concerne le couplage flamme/acoustique et plus spécifiquement l'influence de la température de l'accroche-flamme :une flamme pauvre pré-mélangée air/méthane est stabilisée sur un cylindre dont la température peut être contrôlée. Ainsi, il est montré que l'influence de la température du cylindre sur la flamme – position d'équilibre, dynamique et stabilité - est remarquable. / From small scale energy systems such as domestic boilers up to rocket motors, combustion chambers are often prone to combustion instabilities. These instabilities stem from the coupling of unsteady heat release rate and acoustic waves. This coupling is two sided: flame front perturbations generate acoustic waves while acoustic waves impinging on flame holders can disturb flames attached on them. Important pressure and velocity oscillations can be reached during unstable regimes, that can alter its efficiency or even damage the entire combustion chamber. One major challenge is to understand, predict, and prevent from these combustion instabilities. The objectives of this thesis are twofold: (1) take into account acoustic dissipation and (2)analyze flame/acoustic coupling to obtain Reduced Order Model (ROM) for combustion instabilities. This work is divided into three parts. First, the concept of ROM that gives the acoustic modes of a combustion chamber is introduced. This modeling strategy is based on the acoustic network theory and may take into account flame/acoustic coupling as well as acoustic dissipation. An efficient numerical algorithm dedicated to solve ROMs was designed on purpose and validated on several academical configurations. Second, an experimental rig was commissioned to study mean and acoustic pressure losses across a diaphragm and two swirl injectors. Results show that these two phenomena are linked and can be simply incorporated into ROMs. Finally, flame/acoustic coupling is investigated by using both direct numerical simulations and experiments: a lean premixed V-shaped laminar flame is anchored on a cylindrical bluff-body and we show that its temperature greatly influences the flame mean shape as well as its dynamics.