Thermal flow measurements at Gr/Re2 >> 1 by silicon anemometry

We present the first characteristics of air flow measurements in the mixed convective region with strong buoyancy effects (Gr/Re-2 >> 1), using a thermal silicon double-Wheatstone-bridge vector sensor. The Alternating Direction Method is applied to eliminate additive drift influences. The upper limit on the mixed convective region is experimentally defined to be given by Gr/Re-2 = [0.3-0.8]. Flow velocity measurements of down to 1 mm/s (Reynolds approximate to 0.3) are realized with an accuracy better than 98%.