Comparative study using renormalized group k-ɛ, realizable k-ɛ, and standard k-ɛ models for flow through S-shaped diffuser

Diffusers are mechanical devices that recover static pressure at the expense of the kinetic energy of flowing fluid. The present study is intended about the different design of S-shaped diffusers and its performance characteristics using ANSYS FLUENT17.1 software. The characteristics have been achieved for design of turning angle 62.50/62.50for constant circular center line length 600 mm, constant inlet cross-sectional area 100 × 100 mm2 with constant aspect ratio 2.0 at the outlet for different design of area ratio i.e., 2, 4, and 6 respectively. Incompressible flow analysis has been made at Mach number 0.1176 at the entry of the duct using realizable k-ɛ, standard k-ɛ, and renormalized group k-ɛ model. It has been discovered that flow separation increases, flow uniformity at the exit decreases and overall static pressure loss coefficient (CP) value increases by increasing area ratio for all the design considered. It is also noticed that crossflow velocity is more prominent in the case of the renormalized group k-ɛ turbulent model. Finally, it is found that for the design of an area ratio 2 and 6 the present model gives the best performance in terms of stagnation pressure loss coefficient (CL) and static pressure loss coefficient (CP) respectively.