Development and verification of a local wind prediction model for efficient use of wind energy

《联合国气候变化框架公约京都议定书》将生效，并要求日本大幅减少二氧化碳排放。因此，风能的利用将是重要的。为了更有效地利用日本的风能，在陡峭复杂的地形上进行高精度的风预报是非常必要的。本研究基于流体动力学基本方程，建立了一种新的局地风预报模型，该模型能够准确地预报复杂地形上的分离流场。为了计算实际连续地形上的风场，提出了一种新的侧边界处理方法，以保证任意截面上的质量守恒。结果表明，改进了传统方法对风速的高估或低估，预测风速与全域风速计算结果吻合较好。在进口边界处，增加了一个与计算区域大小相同的区域，以考虑上风地形的影响。结合工程实际，提出了一种修正的残割方法(修正RCM)，该方法能够快速、稳定地求解方程，其速度是传统迭代法的20倍以上。最后，利用真实地形模型进行了大型风洞试验，研究了复杂地形下的流场特性。结果表明，该模型较好地反映了地形汇聚和水流分离引起的加速和减速现象，预报误差在10%左右。结果表明，该模型可用于实际的风能预测，对日本风能的开发具有重要的参考价值。

Kyoto Protocol to the United Nations Framework Convention on Climate Change will take effect, and Japan is demanded to considerably reduce the emission of carbon dioxide. Thus the use of wind energy will be important. For the efficient use of wind energy in Japan, wind prediction with high accuracy over steep and complex terrain is necessary.In the present study, a new local wind prediction model has been developed, which is based on the fundamental equations of fluid dynamics and can accurately predict separated flow field over complex terrain. In order to calculate wind flow over continuous real terrain, a new method for treatment of side boundary was proposed to assure the mass conservation at any cross section. It was found that the overestimation or underestimation of wind speed arising from the conventional method is improved and predicted wind speed by the present method shows good agreement with the wind speed obtained from calculation on whole domain. At an inlet boundary, a domain of same size as the computational domain was added to account for the effect of upwind terrain. For the engineering practice, a modified residual cutting method (Modified RCM) was proposed, which enables the equation to be solved quickly and stably and is as fast more than 20 times as conventional iterative methods. Finally, a large wind tunnel test with the real terrain model was carried out and characteristics of flow field over complex terrain were investigated by the model. It was noticed that the speed-up and speed-down due to convergence of terrain and flow separation was favorably demonstrated and prediction error of the present model was about ten percent. As a result, the present model can be used for the practical wind energy prediction and contributes largely to the wind energy exploitation in Japan.