NOVEL WALL-MOUNTED HOT-FILM SENSORS FOR THE MEASUREMENT OF THE FORCED CONVECTION FROM AN OPEN CYLINDRICAL CAVITY

Kurzfassung

We investigated the forced convective heat loss from a model of a multi-MW cavity receiver of a concentrated solar power (CSP) tower system in a high-pressure wind tunnel. For the tests, arrays of a novel ringlike design of hot-film sensors were placed on the inside wall of the open cylindrical cavity. A constant temperature anemometry (CTA) system controlled these sensors and returned a signal as a function of the instantaneous total heat loss in each sensor. This heat loss was interpolated and averaged to form an integral heat loss value for each given set of wind speed and wind direction. The experiments covered a Reynolds number range of between 2*10^6 and 8*10^6, based on the external flow field. During the 10 days of testing, the ringlike hot-film sensors worked reliably and proved to deliver significant and reproducible results. The maximum forced convective heat loss for the tested geometry occurs at an incident angle of 70°, at all tested Reynolds numbers.