Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Engineering Transactions

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

2D numerical analysis of an H-Darrieus hydrokinetic turbine with passive improvement mechanisms

Guevara-Munoz Angie Judith, Hincapie-Zuluaga Diego Andres, Rodriguez-Cabal Miguel Angel, Sierra-Del-Rio Jorge Andres, Colmenares-Quintero Ramón Fernando, Torres-Lopez Edwar

Engineering Transactions

2023

Vol. 71, iss. 4

553--569

H-Darrieus hydrokinetic turbines are an alternative for small hydroelectric plants. These turbines are considered to have a low environmental impact as they do not require reservoirs. However, they have limited self-starting capacity, which limits their use. Nevertheless, the configuration of passive mechanisms in the H-Darrieus turbines affects their performance, as they tend to increase the flow velocity. This study is part of a project with the aim to design and build a turbine to generate energy in the Colombian river scenario in non-interconnected zones. The objective of this study is to analyze the performance through numerical simulations of four H-Darrieus rotors to be configured with passive improvement mechanisms. The study was conducted using ANSYSr Fluent software, employing transient, two-dimensional models under constant operating conditions. Overlapping meshes were used for the stationary and rotating domain configuration. The results show that increased solidity leads to decreased tip speed ranges and increased maximum rotor power. Improvement in the self-starting capability was found with passive mechanisms employing a diffuser geometry. Among the tested configurations, the rotor configured with a Venturi-shaped mechanism achieved a remarkable 660% improvement in the power coefficient compared to configurations without such mechanisms.

A computational analysis of different geometric ratios at the input of a secondary fluid that affects the efficiency of a subsonic air-air ejector

Hincapie-Montoya Jhon Fredy, Sierra-Del-Rio Jorge Andres, Torres-Lopez Edwar, Hincapie-Zuluaga Diego Andres

Engineering Transactions

2021

Vol. 69, iss. 3

257--269

For this study, the computational fluid dynamics (CFD) technique was used to investigate the combined effects of different geometric parameter relationships; inclination angle variation of the secondary fluid inlet, different lengths of the mixing chamber, and different separation values between the nozzle outlet and the input of the mixing chamber, in an air-air ejector used in a subsonic regime. As a working fluid, the air was used as an ideal gas and its viscosity was expressed as a constant both in the primary and secondary fluids. The renormalization group (RNG) κ−ε turbulence model was used to predict more accurately the way the pressure recovers along the ejector and suitability/applicability to for recirculation flows. It was found in the numerical results that there is an optimal value of the inclination angle for the secondary fluid inlet, the length of the mixing chamber and the separation between the nozzle outlet and the mixing chamber inlet, where the ejector obtains its maximum mass flow ratio. In addition, it was found that the efficiency of the air-air ejector is related to the inclination angle of the secondary fluid inlet.