On swirl development in a square cross-sectioned, S-shaped duct

Ng, Yu Ting; Luo, S. C.; Lim, Teng Joon; Ho, Q. W.

doi:10.1007/s00348-006-0216-8

Cited by 22 publications

(11 citation statements)

References 11 publications

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“…However, in the experimental data these low-pressure regions appear to have merged into a single layer which is not reproduced by the simulations. In fact the simulated results match more closely to those of test section 2 in the experiments of Ng et al 4 where the offset is only 1D h . Figure 5 shows the cross-flow vectors of the simulations compared to experimental data.…”

Section: Iiia S-bend Flowssupporting

confidence: 76%

“…The experiments of Ng et al 4 were used as the basis for assessing the viability of the Hydra code for S-bend ducts. From the experimental data, test section 3 was chosen for the study as it had the greatest offset of the three cases at 1.3D h .…”

Section: Iiia S-bend Flowsmentioning

confidence: 99%

“…This initialises the two vortices which can be seen in S-shaped ducts such as those encountered by Bansod and Bradshaw. The development of the flow in a square cross-sectioned, S-shaped duct was investigated by Ng et al 4 and Taylor et al 5 Flow separation was seen to occur along the lower wall of the first bend as well as along the outer wall of the second bend by both groups of authors. However the secondary flow caused by the first bend is weakened throughout in the second bend due to the opposing swirl created by the secondary flow along the outer wall.…”

Section: Introductionmentioning

confidence: 99%

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CFD Based Study of Unconventional Aeroengine Exhaust Systems

Coates

Page

2012

30th AIAA Applied Aerodynamics Conference

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The effect of upstream duct curvature on the exhaust plume of a jet engine is currently undocumented. Here, three different upstream curvatures are simulated using CFD to investigate the effect of upstream duct curvature on the over-expanded exhaust plume emanating from a rectangular nozzle of aspect ratio 5.8:1 at a nozzle pressure ratio of 2.5 and Reynolds number of 7.61 × 10 5 . Due to the lack of available experimental data for curved ducts connected to high speed jets, the initial work was to validate the methodology for separate S-bend and rectangular nozzle high speed jet cases. These showed that RANS methods were poor for predicting secondary flows in the S-bend and for predicting mixing and potential core length in the rectangular jet. However, LES did show significant improvements for the rectangular jet and correctly predicts the shear layer mixing. Calculations were carried out using an unstructured, median-dual CFD solver with predominantly hexahedral elements containing approximately 65.5−67.5 million nodes. For the combined S-bend and nozzle cases it was seen that increasing upstream duct curvature reduces the potential core length and increases losses in the upstream duct. Transverse total pressure gradients were also observed at the nozzle exit plane in both k-ǫ and WALE LES turbulence models, however to a significantly smaller degree in the latter. The upstream duct curvature was also seen to have an impact on the shock cell development, altering both number and location.

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Section: Iiia S-bend Flowssupporting

confidence: 76%

Section: Iiia S-bend Flowsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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CFD Based Study of Unconventional Aeroengine Exhaust Systems

Coates

Page

2012

30th AIAA Applied Aerodynamics Conference

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“…Similarly to the Hydra code RANS validation study of convoluted ducts by Coates and Page 1 the work of Ng et al 5 will be used to assess both validity of the SEM implementation within Hydra as outlined in section II and the the viability of the Hydra LES code, both with and without the SEM implementation.…”

Section: Validation Studymentioning

confidence: 99%

“…The third test section from the Ng et al 5 experiments, shown in figure 1, will be used again in the validation study due to the large offset and severe curvature of the geometry. …”

Section: Validation Studymentioning

confidence: 99%