Experimental and numerical studies of intensified turbulent heat transfer in round pipes with curved wing vortex generators

摘要

Turbulent airflow and heat transfer characteristics in round pipes with curved wing vortex generators (CWVGs) were numerically and experimentally evaluated for Reynolds number (Re) between 5896 and 20,283. The CVWGs were streamlined and placed in the near-wall regions to reduce the flow blockage. Numerical results showed that counter-rotating vortex pairs were induced at the trailing edge of CWVGs, and these vortices presented a more lasting effect on the downstream flow field with the larger width ratio (WR) or smaller pitch ratio (PR), resulting in the thinning thermal boundary layer and improved fluid mixing. With the increasing WR, the friction factor and Nusselt number were intensified by 195%-604% and 50%-110% over the smooth tube, respectively; the thermal enhancement factor (TEF) increased firstly with WR and reached a peak at WR = 0.20 for Re = 6023, while at WR = 0.15 for other Re. With a reduction in PR, the TEF value reached a peak at PR - 1.0, and the maximum TEF of 1.27 was achieved at Re = 5962, WR = 0.20, and PR = 1.0. Also, correlations for Nusselt number and friction factor were derived according to the experimental data for industrial applications.