Experimental Investigation of Isotropic Flow Generated by Grid in Subsonic Wind Tunnel and Measurement of Characteristics of Turbulent Flow

In this research, the turbulent isotropic flow has been experimentally investigated. Hence, two different grids are made and a contraction channel is installed behind it inside the subsonic wind tunnel to generate anisotropic turbulence flow. The grids with mesh sizes of 2/54 cm and 5/08 cm were cut on the wood with an obstruction ratio of 0/34 and 0/17, respectively. One-dimensional hot wire was used to determine the perturbation velocities in the direction of flow, and an approximation was used to determine the components of other directions. At speeds of 5 m/s and 10 m/s, experiments were performed for each of the grids, which range from a Reynolds number of 8500 to about 33000. To determine the onset of the isotropic location, methods of velocity skewness, kurtosis, turbulence intensity, dissipation rate, and longitudinal scales such as Kolmogorov and Taylor lengths were used. For skewness and kurtosis, the numbers show 0 and 3, respectively, which indicate the isotropic flow. Results showed that with increasing the velocity, the isotropy of the flow was delayed. Also, in a grid with a lower obstruction ratio, the intensity of turbulence will be less near the grid, but as it moves away from the grid, the intensity of turbulence will increase. of by in and [1] Decay of turbulence generated by a square-fractal-element grid. [2] Role of rigid boundary on the decay of turbulence generated by passive-grid for free surface flow. [3] Turbulent flow [4] The use of a contraction to improve the isotropy of grid-generated turbulence. [5] Statistical theory of turbulenc. [6] Experimental investigation and analysis of the velocity variations in turbulent flow. [7] Small axisymmetric contraction of grid turbulence. [8] Decay of vorticity in isotropic turbulence. [9] The decay power law in grid-generated turbulence. [10] Turbulent Flows. [11] Scalings and decay of fractal-generated turbulence. [12] Large scale homogeneous turbulence and interactions with a flat-plate cascade. [13] Turbulence without richardson – kolmogorov cascade. [14] Intermittency and Reynolds number. [15] The spatial origin of− 5/3 spectra in grid -generated turbulence.