CFD MODELLING OF FLOW THROUGH S - SHAPED DUCT

Abstract

Flows in S-shaped ducts find applications in aircraft air intakes. This Project report investigates the flow inside an‘S’ Shaped square Duct. In this report, a computational fluid dynamics (CFD) model of fully developed turbulent flow(k-𝜖 model) is implemented with the help of FLUENT software and the variation of pressure along the length of bend with variation in Reynolds number is analysed. The curvatures is investigated at Reynolds numbers Re=4.73x10 4 and 1.47x10 5. A non-dimensional parameter ω, defined as the total pressure loss coefficient is analysed for finding out the total pressure loss in the duct. Cp Data obtained from the simulation of S-shaped ducts show that there is flow separation at the near side wall of the first bend and far side wall of the second bend. At high Reynolds number separation is more dominant near junction of bend as compare to low Reynolds number flow. To improve the flow in S-ducts, vortex generators and tangential blowing as flow control methods are implemented. Vortex generators “ locally” mix the high momentum fluid in the free stream with the low momentum fluid near the wall and thus energies the boundary layer to suppress flow separation. Tangential Blowing uses mass addition near the separation point to energies the low momentum fluid close to the wall to overcome the adverse pressure gradient. The two methods suppress flow separation and reduce total pressure loss and to improve flow uniformity at the S-duct exit. These methods shown to be effective in suppressing flow separation and reducing total pressure loss.