Experimental setup for low Reynolds number calibration of thermal anemometers

The heat transfer from an electrically heated fine wire of finite length to the surrounding fluid can be decomposed into free and forced convection, c onduction, and radiation. When measuring very lour flow velocities (Re < Gr (1/3)) the influence of free as compared to forced convection has a signifi cant influence on the measured signal. The envisaged experimental setup sho uld clarify the influence of free convection on the three-dimensional heat transfer of cylinders with different aspect ratios and wire temperatures. T o that end measurements must be done under Ig in the earth laboratory and a lso under microgravity (mu g) conditions. Comparison of both measurements, under otherwise identical conditions, allows to distinguish between free co nvective heat transfer and contributions due to conduction and other effect s.