Research of the flow past bluff bodyMohamed KablSupervised bydoc. Ing. Tomáš Vít, Ph.D.Ing. Petra Dančová, Ph.D. 31/5/2016

Outline

• Introduction

• Experimental technique

• Results and discussion

• Conclusion

• Future work

Introduction

Introduction

Hydrodynamic and Aerodynamic bodies

Streamlined body Bluff bodyA body for which the stream-wise dimension is much larger than the cross-flow dimension is often considered to be aerodynamic.

A body which its dimension in the direction of the incoming flow is comparable to its dimension in a direction normal to the flow.

Experimentalprocedures Components

Circular cylinder

Towing tank

Electrolysis hydrogen perciption

Laser sheet L = 300 mm D = 6.6 mm

λ = 45.3

500 X 110 X 110 cm3 Tin Ion Visualization methodWidth =1 mm Frequency = 200 Hz

Experimental procedures

Two different configurations

1. Span wise configuration.

2. Stream wise configuration.

Span wise configuration

Streamwise configuration

Results and discusion Re < 47 Laminar flow regime

47 < Re < 90 Onset of von Kármán vortex regime

90 < Re < 180 Pure von Kármán vortex shedding

Laminar flow regime Re = 30Two attached vortex to the cylinder

Absence of von Kármán vortex

Small cyclic length

Large separation angle 135≃Stagnation angle 0≃

Onset of von Kármán vortex Regime Re = 50Low frequency vortex shedding

Small vortex size

Longer cyclic length

Large separation angle 125 ≃Stagnation angle 0≃Parallel vortex shedding past cylinder

Transition between the onset of von Kármán vortex Regime and the pure vortex shedding regime Re = 90

Reasonable vortex shedding frequency

Intermediate vortex size

Longer cyclic length

Separation angle 110 ≃Stagnation angle 0≃Parallel vortex shedding past cylinder

with periodic oblique shedding

Pure vortex shedding regime Re = 130

High vortex shedding frequency

Large vortex size

Long cyclic length

Small wave length

Unparallel vortex shedding streets

Separation angle 100 ≃Stagnation angle 0≃vortex dislocations

Conclusion

The effect of Reynolds number on the flow past bluff body is extensive on many phenomenon pertinent to the flow.

Re α Vortices frequency (fp)

Re α cyclic Length (Lc)

Re α

Re α

Future work• To invistigate further flow regimes expermentally and numircally.

• To invistigate further phenomenon using another expermental methods.

• To investigate the applications related to von Kármán vortex shedding.

Thank you for your attention!