EFFECTS OF CORNER RADII ON VORTEX-INDUCED VIBRATION WITH FORCED CONVECTION HEAT TRANSFER FROM ANGLED TANDEM-CYLINDER AT LOW RE

Flow-induced vibration (FIV) of the modified tandem-cylinder with a change in corner radii has been investigated in a laminar flow regime with Re=150 and Pr=0.7. The corner radius (r: corner radii, R: cylinder characteristic length) r*=0,0.5,0.75 and 1 are used at a constant angle of attack of 45 degrees. The cylinders are allowed to vibrate in transverse direction while restricted in axial direction with spacing ratio L / D = 4. Computation is carried out with a fixed mass ratio m* = 10 and varying reduced velocity Ur = 2 similar to 10. Constant heating is provided by keeping boundary at a constant temperature. The two-dimensional incompressible Navier-Stokes equations and energy equation are coupled together. Navier-Stokes equations are used with FIV equation of elastically supported cylinder to have flow solutions. Lock-in phenomenon for most of the configuration is occurring at Ur = 6 where vibrational amplitude for most of the configuration is peaked. At Ur =6 for square cylinder, pseudo '2P' can be observed in the wake of r*=0. Vortices at Ur =6 are not merged properly to form a definite type of vortex shedding, although in further downstream weak 2S vortex shedding can be observed. Heating of cylinder is affected by various parameters such as corner radii and spacing ratio with other factors such as early flow separation, reattachment, and vibrational amplitude. Maximum values of Average Nusselt number Nu(avg) is at Ur = 6 for circular cylinder, whereas minimum lies at Ur = 2 for square downstream cylinder. Results give a deep insight into heat transfer getting changed by changing different parameters and will make a base for future study of tube bundles in heat exchangers with FIV.