Homogeneous Turbulence Generation by Non-Linear Interferences between Disturbances in a Low Wavenumber Range (Characteristics of Turbulence by a Random-Phase Mode)

Hiroshi IKEDA, Shigehira OZONO
2013 Transactions of the Japan Society of Mechanical Engineers Series B  
We attempted to generate homogeneous turbulence of high intensity and large scale using a multi-fan wind tunnel. Input signals composed of multiple sinusoidal waves of constant amplitude were fed to each fan with quasi-random phases ("random-phase method"). This method produced approximately homogeneous and isotropic turbulence within a short distance. Although a pulsating component survived for the random-phase method using a single sinusoidal wave, it disappeared when multiple sinusoidal
more » ... were applied. The initially provided rectangular spectrum rapidly changed its form as turbulence convected downstream, and asymptoted to a well-known broader spectrum with a few decades of inertial subrange of slope close to -5/3. The traditional method of generating approximately isotropic turbulence is by means of a grid, for which turbulence Reynolds number Re λ is low, typically in the range 50 to 150. The present method achieved a turbulence-Reynolds number of 753 for the largest amplitude of the input signals. The turbulence characteristics were compared with those of previous studies using active tubulence generation, such as a Makita-style active grid.
doi:10.1299/kikaib.79.555 fatcat:63hp44nxyfhr3ktn5wqzyob344