Purpose of this thesis is to check influence of turbulent model used for simulation of flow close to primary elementi inserted into piping. The goal is to check if results computed by these models are equal and how precise is their prediction.

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An advanced laser-Doppler velocimeter is designed to acquire fully-resolved turbulence structural measurements in high Reynolds number two- and three-dimensional turbulent boundary layers. The new instrument combines, for the first time, new techniques allowing for the direct measurement of particle acceleration and sub-measurement-volume-scale position resolution so that second-order 3D particle trajectories may be measured at high repetitions. Using these measurements, several terms in the Reynolds stress transport equations may be directly estimated, giving new data for modeling and understanding the processes leading to the transport of turbulence in boundary layer flows. Due to the unique performance of the probe, many aspects of LDV instrumentation development were addressed. The LDV configuration was optimized for lowest uncertainties by considering the demanding applications of particle position and acceleration measurements. Low noise light detection and signal conditioning was specified for the three electronic channels. A high-throughput data acquisition system allows for exceptional burst rate acquisition. Signal detection and processing algorithms have been implemented which draw from previous techniques but also address distinctive problems with the current system. In short, the instrument was designed to advance the state-of-the-art in LDV systems. Measurements presented include turbulence dissipation rate and fluctuating velocity-pressure gradient correlations that have been measured in 2D and 3D turbulent boundary layers using the unique capabilities of the CompLDV--many of these measurements are the first of their kind ever acquired in high Reynolds number turbulent flows. The flat-plate turbulent boundary layer is studied at several momentum thickness Reynolds numbers up to 7500 to examine Reynolds numbers effects on terms such as the velocity-pressure gradient correlation and the dissipation rate in the Reynolds transport equations. Measurements are also presented in a pressure-driven three-dimensional turbulent boundary layer created upstream from a wing-body junction. The current results complement the extensive data from previous studies and provide even richer depth of knowledge on the most-completely-documented 3D boundary layer flow in existence. Further measurements include the wakes of three circular-cylinder protuberances submerged in a constant pressure turbulent boundary layer. / Ph. D.

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Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-23T01:44:32Z No. of bitstreams: 1 GUSTAVO GOMES SAMPAIO CURSINO - TESE PPGEQ 2016.pdf: 5939681 bytes, checksum: 518baf4150ea2fb7085706252276b9fa (MD5) / Made available in DSpace on 2018-03-23T01:44:32Z (GMT). No. of bitstreams: 1 GUSTAVO GOMES SAMPAIO CURSINO - TESE PPGEQ 2016.pdf: 5939681 bytes, checksum: 518baf4150ea2fb7085706252276b9fa (MD5) Previous issue date: 2016-04-18 / Este trabalho teve o propósito de determinar o comportamento dos gases na seção de radiação de um combustor de ar que pertence a uma planta industrial. O corpo metálico do equipamento rompeu em seu primeiro ano de operação, devido a um problema conceitual em sua geometria. A fluidodinâmica computacional (CFD), por meio do método dos volumes finitos, foi utilizada para desenvolver um modelo tridimensional que pudesse reproduzir o perfil de temperatura e o comportamento do fluxo do ar de combustão no equipamento. Na simulação, através do uso do software ANSYS CFX, foram utilizados: (i) o modelo de turbulência Reynolds Stress Model (RSM); (ii) as malhas hexaédrica, tetraédrica e prismática; (iii) o modelo de radiação P-1; e (iv) o modelo de combustão Eddy Dissipation Concept (EDC). Como resultado, foram apresentadas quatro possíveis mudanças na geometria do combustor de ar que, caso adotadas, eliminariam os riscos de novas falhas e garantiriam a continuidade operacional da unidade de processo. / This paper has the objective to describe the behavior of the flow and temperature of the flue gas in the radiation section of the vessel used to preheat air in a combustor. The equipment failed in its first operational year, due to a conceptual problem in its geometry. The CFD code based on finite volume method was applied to simulate the physical model of combustor using the ANSYS CFX software, reproducing the main features of the preheater. The simulation had considered: (i) Reynolds Stress Model (RSM) as turbulence model, (ii) The meshes applied were the hexahedral, tetrahedral and prismatic, (iii) P-1 was used as the radiation model and (iv) Eddy Dissipation Concept (EDC) as combustion model. Through the simulation was possible to propose four different kind of combustor geometry modification, that the application of anyone of them would eliminate the risk of new failures, ensuring the unit production availability.