An aerodynamic analysis of a novel small wind turbine based on impulse turbine principles

This document is the Accepted Manuscript of the following article: Pei Ying, Yong Kang Chen, and Yi Geng Xu, ‘An aerodynamic analysis of a novel small wind turbine based on impulse turbine principles’, Renewable Energy, Vol. 75: 37-43, March 2015, DOI: https://doi.org/10.1016/j.renene.2014.09.035, made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License CC BY NC-ND 4.0 http://creativecommons.org/licenses/by-nc-nd/4.0/The paper presents both a numerical and an experimental approach to study the air flow characteristics of a novel small wind turbine and to predict its performance. The turbine model was generated based on impulse turbine principles in order to be employed in an omni-flow wind energy system in urban areas. The results have shown that the maximum flow velocity behind the stator can be increased by 20% because of a nozzle cascade from the stator geometry. It was also observed that a wind turbine with a 0.3 m rotor diameter achieved the maximum power coefficient of 0.17 at the tip speed ratio of 0.6 under the wind velocity of 8.2 m/s. It was also found that the power coefficient was linked to the hub-to-tip ratio and reached its maximum value when the hub-to-tip ratio was 0.45. It is evident that this new wind turbine has the potential for low working noise and good starting feature compared with a conventional horizontal axis wind turbine.Peer reviewedFinal Accepted Versio

Numerical simulation of combined mixing and separating flow in channel filled with porous media

Various flow bifurcations are investigated for two dimensional combined mixing and separating geometry. These consist of two reversed channel flows interacting through a gap in the common separating wall filled with porous media of Newtonian fluids and other with unidirectional fluid flows. The Steady solutions are obtained through an unsteady finite element approach that employs a Taylor-Galerkin/pressure-correction scheme. The influence of increasing inertia on flow rates are all studied. Close agreement is attained with numerical data in the porous channels for Newtonian fluids.Peer reviewedSubmitted Versio

On the turbulent flow models in modelling of omni-flow wind turbine

Yong Chen, Pei Ying, Yigeng Xu, Yuan Tian, 'On the turbulent flow models in modelling of omni-flow wind turbine', paper presented at The International Conference on Next Generation Wind Energy (ICNGWE2014), the Universidad Europa de Madrid, Madrid, Spain, 7th-10th October 2014.The computational fluid dynamics (CFD) has a wide application in the wind energy industry. In CFD simulations, a turbulence model plays a significantly important role in accuracy and resource cost. In this paper, a novel wind turbine, omni-flow wind turbine, was investigated with different turbulence models. Four turbulence models, standard k-ε, realizable k-ε, standard k-ω and SST k-ω models, were employed for this wind turbine in order to assess the best numerical configuration. The performance of these four turbulence models was validated with wind tunnel tests. It is evident that the realizable k-ε turbulence model is most suitable to simulate this novel wind turbine

The Large Deviation Principle and Steady-state Fluctuation Theorem for the Entropy Production Rate of a Stochastic Process in Magnetic Fields

Fluctuation theorem is one of the major achievements in the field of nonequilibrium statistical mechanics during the past two decades. Steady-state fluctuation theorem of sample entropy production rate in terms of large deviation principle for diffusion processes have not been rigorously proved yet due to technical difficulties. Here we give a proof for the steady-state fluctuation theorem of a diffusion process in magnetic fields, with explicit expressions of the free energy function and rate function. The proof is based on the Karhunen-Lo\'{e}ve expansion of complex-valued Ornstein-Uhlenbeck process