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Case Studies: Simulation on Characteristics of Wind Turbine Wake Effect in a Lake-Side Wind Farm with WRF-Fitch
WANG Shu, LIU Shuhua, CHEN Jianzhou, HU Ju, FENG Shuanglei, MA Yulong, MIAO Yucong
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (3): 605-615.   DOI: 10.13209/j.0479-8023.2017.187
Abstract1304)   HTML16)    PDF(pc) (1495KB)(412)       Save

Meso-scale meteorological numerical model WRF (Weather Research and Forecast) and the Fitch Wake model are adopted to reveal the intension and patch range of TWE (turbine wake effect) in various atmospheric stability, as well as the impact of different turbine configuration on utilization efficiency of wind energy. Case studies are conducted over Poyang Lake region. The results are as followed. Horizontally, the patch range of a single wind turbine’s TWE can reach 4 to 10 km downward, with a reduction in wind speed ranging from −0.2 to −1.2 m/s under different atmospheric instability. The reduction in wind speed is more severe with more turbines on the stream track. Among the five cases with different turbine location configuration, the wind speed reducing effect in square case (intensively distributed) is much more apparent than others, while the wind speed in TWE patch tends to recover quickly in hollow diamond case (sparsely distributed). Compared with unstable atmospheric stratification, the TWE under stable atmospheric stratification has a longer patch range, because the turbulent exchange of momentum is intenser in unstable stratification than that in stable stratification. Vertically, the QKE (twice of turbulent kinetic energy) at the wind turbine spot peaks in the core. QKE increases to its maximum value of 19 m2/s2 and then decreases to around zero. The maximum QKE appears at the level of about 90 m above ground level, while the vertical impact of TWE can be traced to a height of 1.1 km.

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Modified CISK-Rossby Waves and Low-Frequency Oscillations
CHEN Jianzhou,ZHAO Qiang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract747)      PDF(pc) (571KB)(362)       Save
A baroclinic semi-geostrophic model with the full, three-dimensional Coriolis acceleration and CISK mechanism is established, f ′ and the non-dimensional parameter η are introduced to represent the nontraditional Coriolis terms and CISK heating, respectively. The modified CISK-Rossby wave solutions of the model are obtained. Dynamics analyses and numerical calculations further confirm that the modified CISK-Rossby waves are very important physical processes in leading to the low-frequency oscillations (LFO) in the tropics.
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