A new approach for the design of diffuser-augmented hydro turbines using the blade element momentum
| Autor: | Jerson Rogério Pinheiro Vaz, Vinicius de Sousa Britto, Antonio Cesar Pinho Brasil Junior, Paulo Augusto Strobel Freitas Silva, Taygoara Felamingo de Oliveira, Déborah A. T. D. do Rio Vaz |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
0209 industrial biotechnology Maximum power principle Renewable Energy Sustainability and the Environment Turbulence business.industry 020209 energy Energy Engineering and Power Technology Thrust 02 engineering and technology Conical surface Mechanics Computational fluid dynamics Turbine Diffuser (thermodynamics) Physics::Fluid Dynamics 020901 industrial engineering & automation Fuel Technology Nuclear Energy and Engineering 0202 electrical engineering electronic engineering information engineering Mass flow rate business |
| Zdroj: | Energy Conversion and Management. 165:801-814 |
| ISSN: | 0196-8904 |
| DOI: | 10.1016/j.enconman.2018.03.093 |
| Popis: | It is known surrounding a turbine with a diffuser may significantly increase its power. This effect has attained considerable attention as it shows theoretically the possibility of achieving a power coefficient about 2 times greater than an ordinary turbine. However, the effect of the diffuser efficiency has not been implemented into blade element momentum yet. Hence, this paper presents a novel approach to design diffuser-augmented hydro turbines considering the diffuser efficiency. Based on the blade element momentum, new expressions for the axial induction factor and thrust are obtained. To assess the proposed model, a comparative evaluation of two different diffusers (flanged conical diffuser and flanged lens diffuser) is performed. A numerical modeling investigation using computational fluid dynamics is carried out based on the Reynolds Averaged Navier-Stokes formulation, using the κ - ω shear-stress transport turbulence model. Evaluations for both turbine and diffuser are performed using experimental data available in the literature. Numerical and theoretical results are compared for a shrouded turbine equipped with a 83% efficiency diffuser. The relative difference observed for the maximum power coefficient between the proposed model and an actuator disk model with diffuser is about 5.3%. For the hydro turbine with flanged conical diffuser, the mass flow rate is about 20 % higher than for a bare turbine, while for the turbine with flanged lens diffuser the increase is only 2.4 % . Also, for the flanged conical diffuser the power is increased by 53 % . Furthermore, it is observed that the proposed blade element momentum with diffuser achieved good agreement with the numerical model, providing improved results compared to other models available in the literature. |
| Databáze: | OpenAIRE |
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