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Transitional boundary layer flow and heat transfer over blocked surfaces with influence of free stream velocity and block height

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Abstract

Velocity, turbulent intensity, static pressure and temperature measurements over the flat plate and blocked surfaces were investigated in a low speed wind tunnel in the presence of free stream velocity and block height. The experiments were carried out for free stream velocities of 5, 7 and 10 m/s encompassing the transitional region and for block heights of 10, 15 and 20 mm forming the different flow samples. A constant-temperature anemometer, a micro-manometer and copper-constant thermocouples were used for measurements of velocity and turbulent intensity, static pressure and temperature, respectively. The results showed that the flow separations and reattachments occurred on the blocked surfaces which enhanced the average heat transfer up to 1.54, 1.71 and 1.84 fold of the flat plate value at 5 m/s for the rising block height, 1.49, 1.68 and 1.80 at 7 m/s, and 1.44, 1.63 and 1.78 at 10 m/s, respectively.

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Abbreviations

Cp :

Pressure coefficient, dimensionless

h:

Convective heat transfer coefficient, W/m2K

h:

Block height, mm

H:

Shape factor, dimensionless

H:

Channel height, mm

K:

Thermal conductivity, W/mK

Nu:

Nusselt number, dimensionless

P:

Pressure, Pa

Pr :

Prandtl number, dimensionless

q:

Heat flux, W/m2

Re x :

Streamwise distance Reynolds number, dimensionless

Re θ :

Momentum thickness Reynolds number, dimensionless

Re H :

Channel height Reynolds number, dimensionless

s:

Block spacing, mm

Tu:

Turbulence level, %

T:

Temperature, °C

u:

Streamwise velocity, m/s

urms :

Root mean square velocity, m/s

U:

Mean free stream velocity, m/s

w:

Block width, mm

W:

Channel width, mm

x:

Streamwise directions, mm

xl :

Unheated starting length, mm

XF :

Length of the recirculation region of downstream surface of the first block, mm

XR :

Reattachment length of the recirculation region of upstream surface of the last block, mm

XT :

Length of the recirculation region of top face of the first block, mm

y:

Pitch wise directions, mm

γ:

Intermittency factor, dimensionless

δ:

Boundary layer thickness, mm

θ:

Momentum thickness, mm

ρ:

Density, kg/m3

o:

Flow-off

f:

Flow-on

in:

Inlet

L:

Laminar

T:

Turbulent

0:

Free stream

w:

Wall

f:

Flat

References

  1. Liou TM, Wu YY, Chang Y (1993) LDV measurements of periodic fully developed main and flows in a channel with rib-disturbed walls. ASME J Fluids Eng 115:109–114

    Article  Google Scholar 

  2. Bilen K, Yapici S (2002) Heat transfer from a surface fitted with rectangular blocks at different orientation angle. Heat Mass Transf 38:649–655

    Article  Google Scholar 

  3. Lee CK, Abdel-Moneim SA (2001) Computational analysis of heat transfer in turbulent flow past a horizontal surface with two-dimensional ribs. Int Commun Heat Mass Transf 28:161–170

    Article  Google Scholar 

  4. Wang L, Sunden B (2007) Experimental investigation of local heat transfer in a square duct with various-shaped ribs. Heat Mass Transf 43:759–766

    Article  Google Scholar 

  5. Igarashi T, Takasaki H (1992) Fluid flow around three rectangular blocks in a flat-plate laminar boundary layer. Exp Heat Transf 5:17–31

    Article  Google Scholar 

  6. Grigoriadis DGE, Kassinos SC (2009) Lagrangian particle dispersion in turbulent flow over a wall mounted obstacle. Int J Heat Fluid Flow 30:462–470

    Article  Google Scholar 

  7. Tropea CD, Gackstatter R (1985) The flow over two-dimensional surface-mounted obstacles at low Reynolds numbers. ASME J Fluids Eng 107:489–494

    Article  Google Scholar 

  8. Wahidi R, Chakrouni W, Al-Fahed S (2005) The behavior of the skin-friction coefficient of a turbulent boundary layer flow over a flat plate with differently configured transverse square grooves. Exp Therm Fluid Sci 30:141–152

    Article  Google Scholar 

  9. Hsieh KJ, Lien FS (2005) Conjugate turbulent forced convection in a channel with an array of ribs. Int J Numer Methods Heat Fluid Flow 15:462–482

    Article  Google Scholar 

  10. Tsia WB, Lin WW, Cheng CC (2000) Computation of enhanced turbulent heat transfer in a channel with periodic ribs. Int J Numer Methods Heat Fluid Flow 10:47–66

    Article  Google Scholar 

  11. Alves TA, Altemani CAC (2010) Thermal design of a protruding heater in laminar channel flow. In: Proceedings of 14th international heat transfer conference, Washington, DC 14:1–10. DOI: http://doi.org/10.1115/IHTC14-22906

  12. Chen YM, Wang KC (1998) Experimental study on the forced convective flow in a channel with heated blocks in tandem. Exp Therm Fluid Sci 16:286–298

    Article  Google Scholar 

  13. Kim SH, Anand NK (1994) Turbulent heat transfer between a series of parallel plates with surface-mounted discrete heat sources. ASME J Heat Transf 116:577–587

    Article  Google Scholar 

  14. Braun H, Neumann H, Mitra NK (1999) Experimental and numerical investigation of turbulent heat transfer in a channel with periodically arranged rib roughness elements. Exp Therm Fluid Sci 19:67–76

    Article  Google Scholar 

  15. Yuan ZX (2000) Numerical study of periodically turbulent flow and heat transfer in a channel with transverse fin arrays. Int J Numer Methods Heat Fluid Flow 10:842–861

    Article  Google Scholar 

  16. Anderson AM (1997) A comparison of computational and experimental results for flow and heat transfer from an array of heated blocks. ASME J Electron Packag 119:32–39

    Article  Google Scholar 

  17. Perng S-W, Wu H-W (2008) Numerical investigation of mixed convective heat transfer for unsteady turbulent flow over heated blocks in a horizontal channel. Int J Therm Sci 47:620–632

    Article  Google Scholar 

  18. Beig SA, Mirzakhalili E, Kowsari F (2011) Investigation of optimal position of a vortex generator in a blocked channel for heat transfer enhancement of electronic chips. Int J Heat Mass Transf 54:4317–4324

    Article  Google Scholar 

  19. Ryu DN, Choi DH, Patel VC (2007) Analysis of turbulent flow in channels roughened by two-dimensional ribs and three-dimensional blocks Part I: resistance. Int J Heat Fluid Flow 28:1098–1111

    Article  Google Scholar 

  20. Herman C, Kang E (2001) Comparative evaluation of three heat transfer enhancement strategies in a grooved channel. Heat Mass Transf 37:563–575

    Article  Google Scholar 

  21. Kline SJ, McClintock FA (1953) Describing uncertainties in single sample experiments. Mech Eng 75:3–8

    Google Scholar 

  22. Atli V (1988) Subsonic flow over a two dimensional obstacle immersed in a turbulent boundary layer on a flat surface. J Wind Eng Ind Aerodyn 31:225–239

    Article  Google Scholar 

  23. Umur H, Ozalp AA (2006) Fluid flow and heat transfer in transitional boundary layers: effects of surface curvature and free stream velocity. Heat Mass Transf 43:7–15

    Article  Google Scholar 

  24. Sinha SN, Gupta AK, Oberai MM (1981) Laminar separating flow over backsteps and cavities Part I: backsteps. AIAA J 19:1527–1530

    Article  Google Scholar 

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Yemenici, O., Firatoglu, Z.A. Transitional boundary layer flow and heat transfer over blocked surfaces with influence of free stream velocity and block height. Heat Mass Transfer 49, 1637–1646 (2013). https://doi.org/10.1007/s00231-013-1208-x

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  • DOI: https://doi.org/10.1007/s00231-013-1208-x

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