基于时域积分的水平轴风力机风轮噪声预测理论及应用

给出了考虑水平轴风力机风轮厚度噪声与负荷噪声的延迟时形式的时域积分解及其噪声预测理论。基于Ffowcs Willians-Hawkings声学方程，减少了偏导数项的求解，提高了计算速度，避免了声学计算中的奇异性问题。对小型水平轴风力机FD2-300在3个方向的辐射噪声进行了预测，得到了声场各种源成分的噪声的分布与指向性规律。计算结果表明：在风轮的旋转平面，具有最大的总噪声级的指向性，负荷噪声在旋转平面以及风力机下游起着主导作用。对于600kW大型水平轴风力机进行了局部区域的噪声现场测量，并且与预测值进行了对比。结果表明：模型的预测结果与测试数据比较符合，且变化趋势一致，在整个测量区域，预测值比测量值低，这是由于计算模型只考虑到风力机叶片的负荷噪声与厚度噪声，对于实际运行的风力机来说，其辐射的总噪声除了与叶片的负荷、厚度有关，还与非定常来流、叶片本身的非定常性和气流粘性有关。若以该文建立的模型进一步考虑风力机的非定常性和粘性效应，将提高其预测准确性，在风力机整体优化设计以及噪声控制方面提供理论指导。

PREDICTION OF HORIZONTAL AXIS WIND TURBINE BLADE NOISE GENERATION AND ITS APPLICATION BASED ON INTEGRAL SOLUTION IN TIME DOMAIN

The integral solution in time domain and noise prediction theory are developed using Ffowcs Willaims Hawkings acoustic equation. The singularity problem is resolved and fast convergence is reached because few partial terms are involved in the system. The calculation of thickness and load noise level and overall sound pressure level is conducted at three directions for small scale HAWT FD2 300 to produce the results about the sound pressure level (SPL) for different noise sources and their directivities. It is demonstrated that the overall SPL approaches to maximum value at HAWT blade rotating plane where strong sound directivity is also identified, the load noise becomes dominant at both rotating plane and downstream of HAWT blade. The measurement of noise radiation for a 600 kW large scale horizontal axis wind turbine was performed downstream along axis. It is shown that the predicted data agrees well with the measurement. It is expected that the prediction accuracy will be promoted, provided that the unsteadiness and viscosity included in the further study.