Navegando por Assunto "Computacional fluid dynamics"

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Acesso aberto (Open Access)
Análise experimental e numérica da fluidização para aplicações industriais
(Universidade Federal do Pará, 2012-03) LOURENÇO, Reimar de Oliveira; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The gas-particle fluidized beds have great importance in the processing industry, due to have a good effect of mixing between the phases, and high rates of heat and mass transfer, requiring it to lower power consumption. Some typical examples of industrial applications of this equipment can be found in processes involving catalytic reactions, catalyst regeneration, or the combustion and coal of gasification. The understanding of the fluid dynamic behavior of this equipment is of fundamental importance for the fluidized bed can be adapted to new conditions. The literature reports several studies of fluidized bed, reporting varied contributions already incorporated the knowledge of the operation. The CFD (Computational Fluid Dynamics) tool has proved a good alternative for understanding the operation of this equipment. The use of multiphase granular Eulerian model together with the conservation equations of mass, energy and momentum for each of the phases present, has shown success when applied to fluidized beds. Overall, this work is to study the behavior of the fluid dynamic flow of glass beads and alumina in conventional fluidized bed type gas-solid, varying models Gidaspow, Syamlal-O’Brien and Wen-Yu, as well as Turbulence Models K-ε and RSM. More specifically, the work seeks to study the behavior of the fluid-dynamic equipment, by monitoring the most important fluid-dynamic parameters, among which we highlight the minimum fluidization velocity of the same, the pressure drop at minimum fluidization equipment, its porosity and expansion of the bed particles, also at minimum fluidization. Experimental tests were compared with numerical simulations using CFD (Computational Fluid Dynamics) tool, in which good agreement of the simulated results compared to experimental results.
Acesso aberto (Open Access)
Estudo do comportamento hidrodinâmico de medidores de vazão de gás liquefeito de petróleo utilizado a teoria do elemento de pá com efeito de grade
(Universidade Federal do Pará, 2021-04-28) PEREIRA, Tiago Miranda; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975; https://orcid.org/0000-0001-6440-4811
Turbine flowmeters are widely applied in industry to quantify transferred amounts of liquid products, even for commercial purposes, due to its high accuracy and large operational range. The development of engineering computational tools to analyze and improve performance of such meters offers to the engineer the possibility of contribution to society, increasing quality of measurements and minimizing distortions in supply chain potentially harmful to final consumers. Most turbine flowmeters have several blades, becoming the determination of lift and drag coefficients still challenge. This makes cascade effect indeed relevant, without which the performance of the turbine can be overestimated by the Blade Element Theory (BET) analysis. Hence, the present work proposes the application of BET to the analysis of hydrodynamic behavior of turbine flowmeters applied to Liquefied Petroleum Gas (LPG) measurement. The proposed model calculates the cascade effect correction due to the local solidity throughout turbine blades length, in order to accurately predict lift and drag coefficients at each blade section. Operational parameters of the studied equipment are obtained from the proposed computational model and compared to the field performance of an existent measurement system for several conditions within the operational range, revealing satisfactory coherence. For this analysis, computational fluid dynamics (CFD) techniques are employed, through the finite volume method. For validation of the CFD model, computational results are compared to in-situ data acquired during regular operation of the measurement system. Cavitation susceptibility is also evaluated through the CFD model, in order to provide indication of boundary limits inside which operational conditions are maintained within specifications. As a result, the study indicates that turbine flowmeter performance can be predicted by the proposed computational modeling strategy based on the BET analysis and field results of angular velocity and linearity can be accurately reproduced.
Acesso aberto (Open Access)
Otimização geométrica de pás de turbinas hidrocinéticas cavitantes sob efeito difusor
(Universidade Federal do Pará, 2022-11-22) PICANÇO, Hamilton Pessoa; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975; https://orcid.org/0000-0001-6440-4811; LINS, Erb Ferreira; http://lattes.cnpq.br/5272283698536321; https://orcid.org/0000-0002-6643-5889
Diffuser technology placed around hydrokinetic rotors may improve the conversion of the fluid’s kinetic energy into shaft power. However, rotor blades are susceptible to the phenomenon of cavitation, which can impact the overall power efficiency. This paper presents the development of a new optimization model applied to hydrokinetic blades shrouded by a diffuser. The proposed geometry optimization takes into account the effect of cavitation inception on the rotor blades surface. The main contribution of this work to the state-of-the-art is the development of an optimization procedure that takes into account the effects of diffuser efficiency, ηd, and thrust, CT d. The model uses the Blade Element Momentum Theory to seek optimized blade geometry in order to minimize or even avoid the occurrence of cavitation. The minimum pressure coefficient is used as a criterion to avoid cavitation inception. Also, a Computational Fluid Dynamics investigation was carried out to validate the model based on the Reynolds Averaged Navier-Stokes formulation, using the κ-ω Shear-Stress Transport turbulence and Rayleigh-Plesset models, to estimate cavitation by means of water vapor production. The methodology is applied to the design of a 10 m diameter hydrokinetic rotor, rated at 250 kW of output power at a flow velocity of 2.5 m/s. An analysis of the proposed model with and without a diffuser is carried out to evaluate the changes in the optimized geometry in terms of chord and twist angle distribution. It is found that the flow around a diffused-augmented hydrokinetic blade doubles the cavitation inception relative to the unshrouded case. Additionally, the proposed optimization model can completely remove the cavitation occurrence, making it a good alternative for the design of diffuser-augmented hydrokinetic blades free of cavitation.