Computational Analysis of Flow Structure in a Curved Subsonic Diffusing Duct

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In the present investigation the distribution of mean velocity, static pressure and total pressure are experimentally studied on a C-shape diffuser of 40° angle of turn with an area ratio of 1.284 and centerline length was chosen as three times of inlet diameter. The experimental results then were 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 different area ratios varying from 1.25 to 2.0 and angle of turn  30° to 75°. The measurements were taken at Reynolds number 2.25 × 105 based on inlet diameter and mass average inlet velocity. Predicted results of coefficient of mass averaged static pressure recovery (48%) and coefficient of mass averaged total pressure loss (12%) are in good agreement with the experimental results of coefficient of mass averaged static pressure recovery (45%) and coefficient of mass averaged total pressure loss (11%) respectively. Standard k-ε model in fluent solver was chosen for validation. From the parametric investigation it is observed that for the increase in area ratio from1.25 to 2.0, static pressure recovery increases sharply but with the increase of angle of turn pressure recovery decreases steadily. The coefficient of total pressure loss almost remains constant with the change in area ratio and angle of turn for similar inlet conditions.
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C-Shape Diffuser; k-ε Model; Fluent Solver; Five-Hole Probe

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