Numerical investigation of flow through a curved annular diffuser

Abstract

In the present investigation the distribution of mean velocity, static pressure and total pressure are experimentally studied on an annular curved diffuser of 30° angle of turn with an area ratio of 1.28. The centerline length is taken as three times of inlet diameter. The experimental results are then numerically validated with the help of Fluent and then a series of parametric investigations are conducted with same centre line length and inlet diameter but with varying area ratios ranging from 1.15 to 3.75. All the measurements are taken at Reynolds number 2.15 × 105 based on the inlet diameter and mass average inlet velocity. Predicted results of mass averaged coefficient of static pressure recovery (32%) and total pressure loss (21%) are in good agreement with the experimental results of mass averaged coefficient of static pressure recovery (28%) and total pressure loss (17%) respectively. Standard k-ϵ model in Fluent solver is chosen for validation. From the parametric investigation it is observed that static pressure recovery increases up to an area ratio of 2.85 and beyond the area ratios 2.85 and up to 3.75, pressure recovery decreases steadily. The coefficient of total pressure loss almost remains constant with the change in area ratio for similar inlet conditions.