Frequency Analysis of Vortex Shedding in Cascade of an Axial Compressor in Moderate Reynolds Numbers

Authors

iran university of science and technology

Abstract

In the present study, measurement and analysis of the dimensionless frequency (Strouhal number) of vortex shedding of an axial compressor cascade in moderate Reynolds numbers was done. Assessment of these effects can help a more precise prediction of wake-induced transition on the downstream blades. To measure the flow field in the wake, the hot film anemometry was used. The measurements were done at three different incidence angles and Reynolds numbers ranging from 240000 to 530000 based on blade chord length and flow velocity. Based on these measurements, there is linear correlation between vortex shedding and Reynolds number and by increasing Reynolds number vortex shedding frequency will increase. The results showed that Strouhal number for Reynolds Number equal or below 360000 had lower scattering compared with the Reynolds Number above 360000. Also, decreasing attack angle will increase wake region. Furthermore, our results showed that vortex shedding frequency at moderate and low Reynolds Numbers displays different behaviors that could be result in different boundary layer formation at trailing edge of blades.

Keywords

Main Subjects

References

[1] Roshko A (1954) On the Development of Turbulent Wakes from Vortex Streets. NACA Rep. 1191.   
[2] Amanifard N (2005) Stall Vortex Shedding Over a Compressor Cascade. Int J Eng 18(1).
[3] Siverding C.H, and Heinemann H (1990) The Influence of Boundary Layer State on Vortex Shedding From Flat plate & Turbine Cascade. ASME J Turbo 112.
[4] Cicatelli G, Sieverding CH (1995) A Review of the Research on Unsteady Turbine Blade Wake Characteristics. AGARD PEP 85th symposium on loss mechanisms and unsteady flows in turbomachinery, derby, May 8-12.
[5] Simoni D, Ubaldi M, Zunino P (2008) Von Karman Vortices Formation at the Trailing Edge of a  Turbine  Blade.  Department  of  Fluid  Machines, Energy Systems and Transportation, University of Genova.
[6] Walker GJ, and Gostelow JP (1989) Effects of adverse pressure gradients on the nature and length of boundary layer transition. Paper No. 89-GT-274, ASME.
[7] Mayle RE (1991) The role of laminar-turbulent transition in gas turbine engines. J Turbomachinery. 113:509-537.
[8] Ardekani MA, Aminy M, Khoshnevis A (2010) Investigation on the determination of flow direction using two parallel Cylindrical hot film sensors. Measurement 43: 527-537.
[9] Swaminathan MK, Rankin GW, Sridhar K (1986) Evaluation of the basic systems of equation for turbulence measurements using the Monte Carlo technique. J Fluid Mech 170: 1-19.
Journal of Solid and Fluid Mechanics
Volume 6, Issue 1
March and April 2016
Pages 19-27

Files

Share

How to cite

Statistics