Effect of angle of turn on flow characteristics of Y-shaped diffusing duct using CFD

The curved diffusers are used in fluid flow systems to decelerate the fluid flow and turn the fluid simultaneously due to space restrictions and design compatibility. The main problem in achieving a high pressure recovery is the flow separation which results in non-uniform flow distribution and excessive losses. The present work is aimed to reveal the fluid flow characteristics in the Y-shaped diffusing ducts; two inlets and one outlet. A set of three Y-shaped diffusing ducts having same curvilinear length and area ratio while varying in the angle of turn (15°, 22.5°and 30°) are considered for the investigation. The Y-shaped diffusing duct is formed by combining two S-shaped circular similar diffusing ducts. The overall area ratio of the Y-shaped duct is 1.5 and the curvilinear length is 600mm. The whole investigation is carried out in two phases; in the first phase a commercial CFD code is verified for the capability against the fluid flow analysis within an S-shaped diffuser and in the second phase, the investigation is carried out to study the effect of angle of turn in the Y-shaped ducts. For the process of validation the established experimental results are used and found that the CFD code applying RNG k-ε turbulence model is predicted the results close to experiments. Taking idea from the validation similar procedure is followed for the remaining analysis. The results are presented in the form of contour plots for the axial velocity distribution and the cross flow velocity distribution is depicted as vector plots. The performance parameters like coefficients of static pressure recovery and total pressure loss are calculated based on the mass-averaged quantities.