The Effect of Inlet Boundary Layer Thickness on the Flow Within an Annular S-Shaped Duct

Sonoda, Toyotaka; Arima, Toshiyuki; Oana, Mineyasu

doi:10.1115/98-gt-260

Cited by 8 publications

(8 citation statements)

References 5 publications

(5 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Experimental measurements show that a large corner separation was formed between the strut and hub and the measured loss coefficient was Y p =0.090. [9] show that duct loss increases by 33% as the inlet boundary layer thickness is increased from 5% of span to 30%. Bailey et al [7] and Karakasis et al [10] show that including an upstream compressor stage increases duct loss; this is principally due to the presence of OGV wakes.…”

Section: Literature Reviewmentioning

confidence: 96%

Super Aggressive S-Ducts for Air Breathing Rocket Engines

Taylor¹,

Flanagan²,

Dunlop³

et al. 2021

Preprint

View full text Add to dashboard Cite

Air breathing rocket engines require turbomachinery and ducting that is substantially lighter than that used in ground based or aerospace gas turbines. In order to reduce the weight of the axial compressor, the design of the inter-spool swan neck duct is targeted. In this paper a circumferential splitter blade is used to reduce loading and diffusion on the duct endwalls. The splitter and duct geometry are coupled and optimised together using 2D CFD. A design is selected that is 30% shorter than ducts that are currently used in aerospace gas turbines and the 3D flow features are investigated in further detail using an experimental rig and 3D CFD.This paper shows that the "splittered" duct has 3 benefits over a conventional duct design: First, separation of the endwalls is prevented even at short duct lengths, this will reduce distortion into the downstream compressor. Second, losses generated by corner separations on structural struts can be reduced by 20%, enabling short ducts to achieve high performance. Third, splittered ducts are shown to be twice as robust to uncertain inlet flow conditions as conventional ducts. This allows a designer to target high performance short designs with reduced risk.

show abstract

Section: Literature Reviewmentioning

confidence: 96%

Super Aggressive S-Ducts for Air Breathing Rocket Engines

Taylor¹,

Flanagan²,

Dunlop³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Furthermore, the numerical results predicted higher losses near the hub owing to a large horse-shoe vortex formation. In further studies, 20 it was shown that the net total pressure losses are not significantly affected. However, the thicker inlet boundary layer notably affects the flow pattern in the S-duct.…”

Section: Introductionmentioning

confidence: 92%

“…These are deceptively simple geometries, but the flow patterns tend to be complicated as indicated in literature. [17][18][19][20][21] The flow develops under stream-wise alternating adverse and favourable pressure gradients and also under a radial pressure gradient. It is known that the hub wall is more susceptible to flow separation due to the curvature and an adverse pressure gradient.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the primary design focus is to reduce the hub wall-flow separation. 20 Sonoda et al 22 reported that increasing the inlet boundary layer thickness has an adverse effect on the hub side flow resulting in increased losses. Furthermore, the numerical results predicted higher losses near the hub owing to a large horse-shoe vortex formation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The effect of inlet distortion on low bypass ratio turbofan engines

Verma

Singh

Pradeep

2020

Proceedings of the Institution of Mechanical Engineers, Part G:

View full text Add to dashboard Cite

Inlet flow non-uniformity, commonly known as inflow distortion, has been a long-standing problem in the history of gas turbine engines. Distortion can be present in the form of total pressure, total temperature or inflow incidence or any combinations of these. The search for better and robust performance requires engines that can sustain a large amount of inlet distortion without considerable loss in the thrust. In the present paper, the effect of total pressure distortion on a single-stage compressor and low bypass ratio fans are studied. Distortion near hub and tip in the form of step radial total pressure profiles is imposed at far upstream of the rotor leading edge. A systematic approach to qualitatively predict the performance maps in the presence of these distortions is discussed. Further, two extents of total pressure distortion are explored for constant inlet distortion intensity. Hub distortion is found to increase the stability margin, whereas tip distortion reduces it. On extending the distortion extent, hub distortion drastically reduces the stability margin, whereas a comparatively lower reduction in stability margin with tip distortion is observed. The critical distortion limit is observed by varying the inlet distortion extent. Also, it is found that downstream ducts in the bypass axial fan do not interact with the upstream fan. This can be exploited to perform independent simulations of the core engine from low bypass ratio fans. Hub distortion is found to drastically affect the duct performance owing to the presence of thicker upstream inlet boundary layer.

show abstract

“…Strut t/c 37% Splitter c/s 87% [9] show that duct loss increases by 33% as the inlet boundary layer thickness is increased from 5% of span to 30%. Bailey et al [7] and Karakasis et al [10] show that including an upstream compressor stage increases duct loss; this is principally due to the presence of OGV wakes.…”

Section: Number Of Struts 12mentioning

confidence: 99%

Super Aggressive S-Ducts for Air Breathing Rocket Engines

Taylor

Flanagan

Dunlop

et al. 2021

Journal of Turbomachinery

View full text Add to dashboard Cite

Air breathing rocket engines require turbomachinery and ducting that is substantially lighter than that used in ground based or aerospace gas turbines. In order to reduce the weight of the axial compressor, the design of the inter-spool swan neck duct is targeted. In this paper a circumferential splitter blade is used to reduce loading and diffusion on the duct endwalls. The splitter and duct geometry are coupled and optimised together using 2D CFD. A design is selected that is 30% shorter than ducts that are currently used in aerospace gas turbines and the 3D flow features are investigated in further detail using an experimental rig and 3D CFD. This paper shows that the “splittered” duct has 3 benefits over a conventional duct design: First, separation of the endwalls is prevented even at short duct lengths, this will reduce distortion into the downstream compressor. Second, losses generated by corner separations on structural struts can be reduced by 20%, enabling short ducts to achieve high performance. Third, splittered ducts are shown to be twice as robust to uncertain inlet flow conditions as conventional ducts. This allows a designer to target high performance short designs with reduced risk.

show abstract

The Effect of Inlet Boundary Layer Thickness on the Flow Within an Annular S-Shaped Duct

Cited by 8 publications

References 5 publications

Super Aggressive S-Ducts for Air Breathing Rocket Engines

Super Aggressive S-Ducts for Air Breathing Rocket Engines

The effect of inlet distortion on low bypass ratio turbofan engines

Super Aggressive S-Ducts for Air Breathing Rocket Engines

Contact Info

Product

Resources

About