Experimental Study of Fluctuation, Parameters and High-Order values of velocity in wake Region of a Model car

Document Type : Research Article

Authors

Mechanical Engineering Department, Hakim Sabzevari University, Sabzevar, Iran

Abstract

Abstract: In spite of the fact that turbulence is one of the very old issues in the domain of fluid mechanics, it has been remained unresolved. In this paper is done the experimental investigated on the flow dynamics and the high-order parameters such as Flatness and skewness of wake of vehicle model also is shown The Frequency variations vortex formation at the maximum amplitude, strohal Number and Length scale Incorporation. All testing was performed aerodynamic Hakim Sabzevari University To measure the flow characteristics, the wind tunnel and a hot wire flow meter Made by Saba Frasnjsh is used. The maximum disturbances and nominal maximum speed of the device, respectively are, 0. 1% and 30 m / s. The results showed: Skewness values at lower altitudes are less than its values at higher altitudes that it has a reverse trend with increasing distance from the vehicle. Flatness values gradually decreased with increasing distance from the vehicle. The strohal number is often reduced by increasing the distance between car and trailer. And mixing length scale within the wake often has one or two maximum peaks. The wake of Trailer for near car locations to the trailer dosent have any Effect on the formation of the maximum peak is mixing length scale.

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References

[1] Durst F., J. Jovanović and Lj. Kanevče, “Probability density distribution in turbulent wall-bounded shear layer flows”, Turbulent Shear Flows, Springer-Verlag, 5(1987): 197-220.
[2] Veeravalli, S. and Z. Warhaft, “The shearless turbulence mixing layer”, Journal of Fluid Mechanics, 207 (1989):191-229.
[3] Kang, H. S. and C. Meneveau, “Experimental study of an active grid-generated shearless mixing layer and comparisons with large-eddy simulation”, Physics of Fluids, 20 (2008): 115-102.
[4] Matović, M., “Experimental investigation of free premixed flame flow field, by laser anemometer”, Master thesis, University of Belgrade, Faculty of Mechanical Engineering in Belgrade, (in Serbian), 1998.
[5] Petrović, V. D., “Research of turbulent fluid flow in the free round isothermal jet by hot wire anemometer”, Master thesis, University of Belgrade, Faculty of Mechanical Engineering, (in Serbian), 1991.
[6] Sterlund, Jens M. and Arne V. Johansson, “Turbulence Statistics of Zero Pressure Gradient Turbulent Boundary Layers”, 13th European Turbulenc conference, Warsaw, September 2011.
[7] Ahmed‚ S. R.‚ R. Ramm and G. Faltin‚ “Some Salient Features of the Time Averaged Ground Vehicle Wake”‚ " SAE Technical Paper Series 840300‚ Detroit, 1998.
[8] Gilli, P. and F. Chometon, “Modelling of Stationary Three-Dimentional Separated Air Flows around an Ahmed Reference Model”, Third International Workshop on Vortex, ESAIM Proceedings, 7.10 (1999): 124.
[9] Hanaoka, Y. And A. Kiyohira, “Vehicle Aerodynamic Development using PAMFLOW”, 2003.
[10] Gillieron, P. and A. Spohn, “Flow Separations Generated by a Simplified Geometry of an Automotive Vehicle”, 2007.
[11] Lienhart, H. and C. Stoocks, “Flow and Turbulence Structures in the Wake of a Simplified Car Model (Ahmed Model)”, DGLR Fach Symp. Der AG STAB, Stuttgart UNIV., 15-17 Nov, 2010.
[12] Khalighi, B., S. Zang, C. Koromilas, S. Balkanyi, L.P.Bernal, G. laccarino and P. Moin, “Experimental and Computational Study of Unsteady Wake Flow Behind a Body with a Drag Reduction Device”, SAE PPR. 2006- 01-1042.
[13] Javareshkiyan, M.H. , R. Shayesteh Sadafiyan and A. Azarkhish, “Numerical and Experimental investigation of Aerodynamics forces on the base model of vehicle” , SID, 18.1 (1385): 49-64.(in Persian)
[14] Watkins, S., G. Vino, “The Effect of Vehicle Spacing on the Aerodynamics of Representative Car Shape”, J. of Wind Engineering and Industrial Aerodynamics 961232-12393ED., 96.3 (2011): 1232-1239.
[15] Khoshnami Deshiri, M. and M. Fathali, “Numerical study of the impact of the initial turbulent integral length scale on the dynamics of a two dimensional shear-free turbulent mixing layer”, Fluid Mech., 14 (2014): 113– 123.
[16] Saha, A. K., K. Muralidhar and G. Biswas, “Experimental Study of Flow Past a Square Cylinder at High Reynolds Numbers”, Experiments in Fluids, 29.4 (2008): 553-563.
[17] Shadaram A. Azimifrad M. and Rostami N. “Study of characteristic flow at the near wake of square cylinder” J. of Mechanical- aerospace, 3.4 (1386).(in Persain)
[18] Sanieenezhad, M., “ an intrudaction to fluctuation flow and turbulence modeling”, Tehran, 1383.
[19] Goldstein, S. “A Note on the Measurement of Total Head and Static Pressure on a Turbulent Stream”, Proceedings of the Royal Society of London, Series A,155.32 (1936): 570-575.
[20] Jogensen Finn, E., “How to measuer turbulence with hot-wire anemometers”, Dantec Dynamics, 2002.
Amirkabir Journal of Mechanical Engineering
Volume 49, Issue 1
April 2017
Pages 83-92

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