The combination of PIV and heat flux measurement in study of flow and heat transfer near a circular finned cylinder

Abstract

The flow and heat transfer of the finned cylinder are investigated by the methods of PIV, gradient heat flux measurement and thermometry. On the hollow model of a circular cylinder heated by saturated water vapor at atmospheric pressure, five annular fins of 20 mm high and of 10 mm thick are mounted. For the first model, the “acting” fin was hollow, for the second, it was solid and made of titanium alloy VT22. The remaining four fins simulated flow blockage. To visualize the flow in the intercostal space, the fin simulators were made of Perspex. Battery gradient heat flux sensors (GHFSs) with volt-watt sensitivity of 10 mV/W, were installed on the “acting” fin at different distances from the surface of the carrier cylinder. The cylinder rotated around its axis at an angle of φ = 0…180°, which made it possible to obtain the distribution of heat flux over the surface of the fin. By combining PIV diagnostics and gradient heat flux measurement, it was possible to obtain a complex 3D structure of the flow in the intercostal space and the distribution of heat flux on the surface of the fin. The values of the local heat transfer coefficients (HTCs) were also obtained. The dependence of HTC on flow mode and intercostal space is revealed. Comparison of the obtained characteristics for models with hollow and solid fins allowed us to determine in experiment fin efficiency for different intercostal spaces and free-stream velocities. The combination of all three technologies opens up new possibilities in study of flow and convective heat transfer.