基于谐波合成法的大涡模拟脉动风场生成方法研究

为准确模拟大涡模拟入口处的脉动信息,在充分考虑脉动风场的功率谱、相关性、风剖面等参数前提下,运用谐波合成方法生成了满足目标风场湍流特性的随机序列数,通过对FLUENT软件平台进行二次开发,将生成的随机序列数赋给大涡模拟的入口边界,从而实现了大涡模拟的脉动输入.基于风洞试验数据,分别建立了两种模拟脉动风场的数值模型,一为没有任何障碍物的空风洞,运用谐波合成方法生成的随机序列数作为入口边界来生成脉动信息;二为与真实风洞一致的尖劈粗糙元风洞,采用平均风作为入口边界,利用尖劈粗糙元对风场的扰动来产生脉动信息.通过对比两种数值模型发现:基于谐波合成方法生成的脉动风场可作为大涡模拟的入口边界,可为大涡模拟脉动入口研究提供参考.

Research on Generating Method of Fluctuating Wind Field of LES Based on WAWS

In order to accurately simulate the inlet boundary conditions of turbulence information of Large Eddy Simulation (LES), the fluctuating time-history data satisfying the target wind field were simulated with the weighted amplitude wave superposition (WAWS) considering the integral scale, power spectrum, turbulence intensity and wind velocity profile. The fluctuating time-history data were given to the inlet boundary of LES by the secondary development of the commercial software FLUENT. Consequently, the fluctuating information of the Large Eddy Simulation was obtained. The two numerical models were established on the basis of the experiment data in the wind tunnel. The first was the flow field without any obstacles in which the fluctuating time-history data simulated by WAWS method were the inlet boundary condition. The second was the flow field with spires and roughness element model in accordance with those in the wind tunnel, in which the mean wind velocity was given to the inlet boundary and the wind turbulences were generated by the spires and roughness elements. The results show that fluctuating wind field based on the WAWS method can be the inlet boundary for the LES and provides a reference for the investigation of the inlet boundary conditions of LES.