Numerical Study of Von Kármán Vortex Streets Inside Heat Exchangers

This study highlights the occurrence of vortex shedding for flow around a bluff cylindrical object for Reynold’s number between 500 and 1400. Using a heat exchanger model with a single tube, the vortex shedding in the wake of the cylindrical tube is numerically studied for various Reynold’s number. The shedding frequency is also determined and the Strouhal number, St, computed. The values of Strouhal numbers obtained are found to compare with those found in literature. The presence of lift and drag forces, which occurs as a result of the vortex shedding are also observed. These can lead to catastrophic vibrations in the tubes when the vortex shedding frequency resonates with the natural frequency of the tubes. The effects of variation of fluid properties due to temperature on vortex shedding and shear stress are also studied. Finally, a characteristic tube bank is used to study the damping effects created by adjacent tubes in a typical heat exchanger tube array.