CFD analysis of performance characteristics of Y-shaped diffuser with combined horizontal and vertical offsets

This paper presents the effect of combined horizontal (90°/90° turn) and vertical offsets (inlet and outlet in two different horizontal planes) on Y-shaped diffuser with rectangular inlet (AS=2AS=2) and circular outlet with area ratio 2 with downstream settling length 1.5D   at Reynolds number 2.74×1052.74×105. A computer program based on finite volume technique, using standard k–ε turbulence model, has been adopted and modified to predict the flow. The results obtained from this study indicate reduced outlet pressure recovery accompanied with increase in non-uniformity in flow at the exit contributed by the offset effect. The comparison of pressure recovery with high vertical offset value of 1.25D with zero vertical offset indicates that there is significant drop of pressure of the order of 5%. Non-uniformity in flow at the outlet also increases from 5 to 9% from zero to 1.25D vertical offset due to offset effect. This paper also shows that increase in Reynolds number has marginal effect on the outlet pressure recovery for all cases of offset. The Y-shaped diffusers analyzed in the present study fulfill most of the requirements of the flow diffusion process efficiently and effectively.