Study of strong temperature mixing in subsonic grid turbulence

• Published in: The Physics of fluids (1958) 1973-10, Vol.16 (10), p.1587-1598
• Main Authors: Lin, Shih‐Chun, Lin, Shao‐Chi
• Format: Article
• Language: English
• ISSN: 0031-9171; 2163-4998
• DOI: 10.1063/1.1694184

Strong temperature mixing in subsonic air turbulence is studied in an open‐circuit wind tunnel with a 0.5 m cross section. The specially constructed heating grid consumes up to 300 kW of electric power at a mean flow velocity of 11 m/sec. The highest mean absolute temperature 〈T〉 reaches 370°K, while the rms temperature fluctuation θ′ at midtunnel is typically 6°K. Basic statistics of the temperature field are measured and discussed. It is found, in particular, that (i) the streamwise decay of the normalized mean‐square temperature fluctuation (θ′ / ) 2 is not sensitive to the applied heating rates, suggesting that so far buoyancy contributes little to the dynamics of the turbulence; (ii) the observed decay rates are much higher than those reported by others in the literature and are consistent with the higher drag characteristics of the present grid; (iii) the temperature fluctuation spectrum, when normalized by local fluid properties and dissipation rates, retains a universal form and show an inertial‐convection subrange of limited extent; (iv) the one‐dimensional universal scalar inertial Kolmogoroff constant, β 1 , determined from such subrange has a value of 0.60±0.06.