Effect of turning angle on performance of 2-D turning diffuser via Asymptotic Computational Fluid Dynamics

The present work aims to numerically investigate the effect of varying turning angle, ϕ = 30° - 90° on the performance of 2-D turning diffuser and to develop the performance correlations via integrating the turning angle using Asymptotic Computational Fluid Dynamics (ACFD) technique. Standard k-ε adopting enhanced wall treatment of y+ ≈ 1.1 appeared as the best validated model to represent the actual cases with deviation of ±4.7%. Results show that the pressure recovery, Cp and flow uniformity, σout are distorted of respectively 37% and 28% with the increment of turning angle from 30° to 90°. The flow separation starts to emerge within the inner wall, S=0.91Lin/W1 when 45° turning diffuser is applied and its scale is enlarged by further increasing the turning angle. The performance correlations of 2-D turning diffuser are successfully developed with deviation to the full CFD solution approximately of ±7.1%.