短试验段内格栅湍流场风洞试验研究

为在轴向距离较短的风洞中调制出局部高湍流场，利用风洞试验的方法，对5种格栅（2种方型格栅、3种竖条格栅；3 cm × 3 cm截面铝制型材组装）后的近流场区域进行热线风速仪测量，得到格栅后近场区域的湍流参数分布及各向同性特性，依据相关湍流参数的变化规律，引入无量纲量拟合近场区域湍流强度变化规律经验公式，拟合优度为0.96。分别利用经典和现代谱估计对湍流功率谱密度进行分析，对比发现不同形式的谱估计均能准确预测近场区域湍流功率谱密度，仅在低频处存在偏差。通过改变格栅与测点距离、来流速度以及栅条结构的形式，可以改变格栅湍流场中的能量结构。

Wind tunnel experimental study of the grille-generated turbulence in the short test section

The objective of the current work is to modulate the local high turbulent field behind grilles through a wind tunnel with a short axial distance. The flow fields formed by five types of grilles (two mesh grilles and three vertical bar grilles, 3 cm × 3 cm sectional aluminum profiles assembly) were experimentally tested by the hot-wire anemometer. The turbulent parameters distribution and isotropic characteristics of the turbulent flows near behind the grilles are obtained. Besides, the fitting formulas for turbulent flows are acquired according to the changing law of parameters, and the goodness of the fitting is 0.96. Meanwhile, the classic spectrum estimation and modern spectrum estimation are adopted to analyze the turbulent power spectrum density (PSD), respectively. It is noted that different spectral estimators can accurately predict the turbulent PSD at the near-field region, and the deviations exist only at low frequencies. Besides, by adjusting the distance between the grilles and the measuring point, the wind speed, and the grille structure, the energy structure behind the grille turbulent field can be changed.