Multi-method research of flow and heat transfer for the tube with circular fins

PIV, heat flux measurement and thermometry were combined in real time, for a comprehensive research of air flow and heat transfer at non-isothermal surface of the tube with circular fins. Gradient heat flux sensors (GHFSs) with response time of 10‒8 ... 10‒9 s fix the value of heat flux per unit area practically instantaneously. We have identified regime and geometrical effect on heat transfer supplemented with results of gradient heat flux measurement, thermometry data, and velocity fields. The experiments covered a range of Reynolds numbers of Re = 0.4...5×104. The gap of measurements (by the azimuth angle of ) of heat flux and temperature was 20°. The spaces between the fins varied within δ = 5...20 mm. According to the results of heat flux measurement and thermometry, local and then average over the surface heat transfer coefficient (HTC) for various regimes were calculated. Using a model with hollow and solid fins made it possible to evaluate experimentally the effectiveness of a circular fin.