Turbulence Intensity Measurement in the Test Section of Shiraz Wind Tunnel Using Hot Wire Anemometry

Large-scale flow field computation and wind tunnel experimental testing are both essential tools in the field of aerodynamics research and development. Despite the high cost of wind tunnel testing, it is an essential tool for validation of computational results, ensuring air vehicle flight safety. The evaluation of flow quality in test section of a wind tunnel is a crucial step for professional operation the tunnel. Although, several experiments have been carried out to measure flow uniformity and variation in Shiraz University Transonic Wind Tunnel (SUTWT), there is no information available on free turbulence intensity of this tunnel. Therefore, as a first step in examining the free turbulent flow quality in the test area of SUTWT, this study is attempted. In this research, turbulence parameters such as turbulence intensity, skewness, kurtosis, power spectrum and velocity profiles at various stations of the test section in different operational states of the tunnel examined using hot wire anemometry. The ultimate findings of the study reveal an average turbulence intensity of 0.45 and 0.51% at Mach 0.32 and 0.4, respectively. However, due to possible existence of rake vibration and acoustic noise of engines, it is expected that the actual turbulence intensities would be lower. Moreover, the measured statistical values, including skewness and kurtosis, have been appropriately validated to ensure the optimal Gaussian distribution, and a comparison between the variations of the free stream power spectrum and the decay line of the Kolmogorov energy spectrum indicates a satisfactory correlation.