80 Thermal Performance Analysis of A Circular Tube Using Vortex Rings at Various Angle and Pitch Ratio Authors: Eknath.Kurhe, Sameer Bhosale Thermal Performance Analysis of A Circular Tube Using Vortex Rings at Vario... 2017/May/21 ( 33 downloads) Abstract The influence of inclined vortex rings (VR) on heat transfer augmentation in a uniform heat-fluxed tube has been investigated experimentally. In the present work, thevortex rings were mounted repeatedly in the tube with various angle (250,300,350) and geometry parameters of the VR, three relative pitch ratios (PR = P/D = 2, 1 and 0.5) and at constant relative ring blockage ratios (BR = b/D = 0.2). Air was employed as the test fluid in the tube for the Reynolds number from 12000 to 24,500. The aim at using the VRs is to create counter-rotating vortices inside the tube to help increase the turbulence intensity as well as to convey the colder fluid from the core regime to the heated-wall region. The experimental results show a significant effect of the presence of the VRs on the heat transfer and pressure loss over the smooth tube. The larger BR value provides higher heat transfer and pressure loss than the smaller. The Nusselt number is maximum for vortex ring angle 350, but due to the large increase in the friction factor, thermal performance decreases. However, the VR at BR = 0.2 and PR = 0.5 with 300 yields the best thermal performance. Keywords: Heat transfer,inclined vortex ring,Circular Tube, Turbulators, Nusselt number.