The wind energy exploitation technique has been developed very quickly in recent years. The vertical axis wind turbine is a hot research domain due to several advantages: low noise, flexible for installation, ease of maintenance, great safety and credibility, etc. The aerodynamic performances of different forms of airfoils including an active deformation airfoil and a fluid-solid coupling passive airfoil with two-dimensional (2D) and three-dimensional (3D) cases have been investigated numerically in this paper. Firstly, the aerodynamic performances of the airfoils with the maximum deformation amplitudes of their cambers which are 3%, 5% and 7% of the chord length have been discussed, respectively, with the angles of attack in the range of 0° and 20°. Secondly, for the angle of attack set at 18°, the two-way fluid-solid coupling simulations with the Young’s Modulus of 1 Mpa and 2 Mpa have also been investigated. Results show that: (1) for the pseudo 3D and real 3D single active deformation airfoil cases, the lift coefficients increase as the maximum deformation amplitudes augment from 3% to 7% of the chord length at the same angle of attack. With the same maximum deformation amplitude, when the angles of attack increase from 0° to 20°, the lift coefficients which increase firstly and then decrease are bigger than that of the original NACA0012 airfoil. When the maximum deformation amplitude of the pseudo 3D airfoil reaches 5% of the chord length, a relatively good aerodynamic performance with better inhibition effect of vortex generation can be obtained. The 3D vortex distribution demonstrates that the deformable airfoil has a better vortex generation controlling effect at the middle cross-section along the spanwise direction than the non-deformable airfoil. (2) From the aspect of fluid-solid coupling, the lift increases and the drag decreases so that the lift to drag ratio has a big improvement when the Young’s Modulus is equal to 1Mpa and 2Mpa. The deformable airfoil can inhibit the generation and the shedding of the surface vortex when the fluid-solid coupling effect is considered.
Thermal radiation is dominant in oxy-fuel combustion technology. When considering the difference between conventional air combustion and burgeoning oxy-fuel combustion caused by diverse components of fuel gas, it is critical to improve the accuracy of numerical simulation for radiation
by CFD. The line-by-line model is considered as the most accurate approach to simulate thermal radiation while it will cost vast calculation resources on the other hand. This approach is applied as a benchmark for the validation of other approximate models in most cases. The corrected-K
distribution method (CK) has attracted considerable attentions in recent years. the NBCk model always has an excellent performance when the temperature gradients are small. However, when the temperature gradient gets higher, the correlation assumption breaks down and leads to non-negligible
errors. To improve the accuracy of the CK model, we introduced a new method called the multi spectral corrected-K distribution model based on the functional data analysis (FDA) in this work. The objective of this MSCK method is to group together wavenumbers according to
the spectral scaling functions defined as the ratio between spectra in different thermophysical states. Over these intervals, the correlation assumption can be considered as nearly exact. Results show that the MSCK model always achieves a better performance on calculation accuracy
while sharing the same computational cost as the traditional CK model.
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