Flow analysis in s-shaped diffusers with circular cross-section

Abstract EN

Curved diffusers, which are widely used as aircraft intake ducts, accomplish certain objectives for prescribed inlet flow conditions within geometric limitations.

Investigations on curved diffusers are scanty, with little information on the effects of area ratio (AR), angle of turn of the centerline (Δβ), and shape of the centerline on the performance, although other aspects of flow in such ducts have been studied [1–15].

On the basis of the available literature, it is seen that investigations on circular cross-section S-diffusers with area ratio greater than 1.5 have not been reported.

The effect of turn angle (Δβ) in such diffusers is still to be investigated.

An attempt has been made in the present study to establish the effect of AR (1.5, 2.0, 2.5, and 3.0) and turning angle Δβ (15° / 15°, 22.5° / 22.5°, and 30° / 30°) on the performance of an S-diffuser with fixed centerline length of 264 mm and inlet velocity of 40 m / s, using the commercial CFD code FLUENT.

The predictions have been carried out for steady and incompressible flow.

The code was validated with the experimental results reported by Rojas et al.

[6] on a circular cross-section 22.5° / 22.5° S-diffuser with AR = 1.5.