Some aspects of the flow in S-shaped diffusing ducts

Abstract

The circular cross-sectional Royal Aerospace Establishment (RAE) 2129 S-shaped intake diffusing duct series, shown in Fig. 1, which has an offset of the inlet and exit centerline of 0·3 and 0·45 of the axial length of the duct, was designed at the RAE (Bedford) and tested at British Aerospace Filton, at low forward speeds (freestream Mach no. range from 0 – 0·2 but a range of duct inlet Mach numbers up to choking speeds) in the last two decades to fulfil the objectives of collecting systematic experimental data on engine face pressure recovery, total pressure flow distortion and wall static pressures for computational fluid dynamics validation. Some of the measurements have been presented, as for example, by Willmer, Brown & Goldsmith. The measurements from one version of Model 2129 (the 0·3 length offset S-duct geometry) have been used to compare with calculated results from a number of CFD programs, as for example, by Anderson, Horton and by the AGARD Working Group 13. The series of comparison also highlight the need for measurements other than the engine face total pressure and wall static pressure which have already been made.

Experimental Investigation of Flow Parameters in a Mild Curved S-shaped Diffusing Duct

“…Change of flow rotation of the secondary motion also been observed in the second bend compared to the previous half and strength of the counter rotating vortices increases in the downstream sections of the diffuser. These observations are in line with Taylor et al[4], Whitelaw et al[7], Yu[16].…”

Study and Numerical Analysis of Compressor Transition Duct

“…In a circular cross sectioned S-duct diffuser, flow separation results in a comparatively large pair of contra-rotating stream-wise vortices, which occupy about a third to a half of the S-duct exit area. Such problems were investigated by many researcher [13][14][15] for circular cross sectioned diffusers. Hak et al [16] and Lin [17] discussed separation flow control in a review.…”