### Experimental study of the turbulent boundary layer in the presence of a rectangular perforated rib

**Published:**05.07.2019

**Authors:** Afanasiev V.N., Kong Dehai , Getya S.I., Trifonov V.L.

**Published in issue: **#7(91)/2019

**DOI: **10.18698/2308-6033-2019-7-1897

**Category:** Aviation and Rocket-Space Engineering | **Chapter:** Aerodynamics and Heat Transfer Processes in Aircrafts

Separated flows are widespread in many areas of science and technology, such as space technology, aviation, gas turbines, etc., which has a significant effect on the processes of hydrodynamics and heat transfer in them. The separation of the flow and its reattachment can serve as a powerful means of enhancing heat and mass transfer processes, and its organization is quite simple and reliable in terms of technology. This paper presents the results of the experimental study on hydrodynamics and heat transfer in the separation zone in front and behind a single rectangular perforated rib located on a flat plate heated by the law of qw = const. Experimental measurements were carried out using the Pitot-Prandtl tube and Dantec Dynamics hot-wire anemometry system, which allows us to obtain new characteristics of the turbulent boundary layer, both mean and oscillatory ones. We analyzed the influence of the perforation ratio of the rib and the location of the holes in the rib on the heat transfer efficiency. It was established that the stagnant and recirculation zones in front and behind the perforated rib were shifted and became smaller or disappeared. Findings of research show that jet flows, impinging on the heat transfer surface from the perforation holes, provide more efficient heat transfer behind the perforated rib, compared to that behind the solid rib.

**References**

**[1]**Afanasiev V.N., Veselkin V.Yu., Leontiev A.I., Skibin A.P., Chudnovsky Ya.P. Thermohydraulics of flow over isolated depressions (pits, grooves) in a smooth wall. Heat Transfer Research, 1993, vol. 25 (1), pp. 22–56.

**[2]**Isaev S.A., Leontiev A.I., Kudryavtsev N.A. Numerical Simulation of Hydrodynamics and Heat Transfer under Conditions of Turbulent Transverse Flow Past a “Trench” an a Plane Surface. High Temp., 2005, vol. 43 (1), pp. 89–102.

**[3]**Afanasyev V.N., Chudnovsky Ya.P., Leontiev A.I., Roganov P.S. Turbulent flow friction and heat transfer characteristics for spherical cavities on a flat plate. Exp. Therm. Fluid Sci., 1993, vol. 7 (1), pp. 1–8.

**[4]**Leontiev A.I., Kiselev N.A., Burtsev S.A., Strongin M.M., Vinogradov Y.A. Experimental investigation of heat transfer and drag on surfaces with spherical dimples. Exp. Therm. Fluid Sci., 2016, vol. 79, pp. 74–84.

**[5]**Larichkin V.V., Yakovenko S.N. Effect of boundary-layer thickness on the structure of a near-wall flow with a two-dimensional obstacle. J. Appl. Mech. Tech. Phys., 2003, vol. 44 (3), pp. 76–84.

**[6]**Wang L., Salewski M., Sunden B. Turbulent Flow in a Ribbed Channel: Flow Structures in the Vicinity of a Rib. Exp. Therm. Fluid Sci., 2010, vol. 34, pp. 165–176.

**[7]**Afanasiev V.N., Kong D.H. Rectangular Ribs in Turbulent Boundary Layer on the Initially Smooth Surface. J. Phys. Conf. Ser., 2017, vol. 891, 012140.

**[8]**Terekhov V.I., Yarygina N.I., Zhdanov R.F. Heat Transfer in Turbulent Separated Flows in the Presence of High Free-Stream Turbulence. Int. J. Heat Mass Transf., 2003, vol. 46, pp. 4535–4551.

**[9]**Smulsky Ya.I., Terekhov V.I., Yarygina N.I. Heat Transfer in Turbulent Separated Flow Behind a Rib on the Surface of Square Channel at Different Orientation Angles Relative to Flow Direction. Int. J. Heat Mass Transf., 2012, vol. 55, pp. 726–733.

**[10]**Tariq A., Panigrahi P.K., Muralidhar K. Flow and Heat Transfer in the Wake of a Surface-Mounted Rib with a Slit. Exp. Fluids, 2004, vol. 37, pp. 701–719.

**[11]**Kalinin E.K., Dreitser G.A., Yarkho S.A. Intensifikatsiya teploobmena v kanalakh [Heat transfer enhancement in channels]. Moscow, Mashinostroenie Publ., 1990, 206 p.

**[12]**Migay V.K. Povyshenie effektivnosti sovremennykh teploobmennikov [Heat exchanger efficiency improvement]. Leningrad, Energiya Publ., 1980, 144 p.

**[13]**Terekhov V.I., Bogatko T.V., Dyachenko A.Yu., Smulskiy Ya.I., Yarygina N.I. Teploobmen v dozvukovyh omryvnyh pomoka [Heat transfer in subsonic separated flows]. Novosibirsk, NSTU Publ., 2016, 247 p.

**[14]**Liou T.M., Chen S.H. Turbulent Heat and Fluid Flow in a Passage Disturbed by Detached Perforated Ribs of Different Heights. Int. J. Heat Mass Transf., 1998, pp. 411795–1806.

**[15]**Hwang J.J., Lia T.Y., Liou T.M. Effect of Fence Thickness on Pressure Drop and Heat Transfer in a Perforated-Fenced Channel. Int. J. Heat Mass Transf., 1998, vol. 41, pp. 811–816.

**[16]**Sara O.N., Pekdemir T., Yapici S., Yilmaz M. Heat-Transfer Enhancement in a Channel Flow with Perforated Rectangular Blocks. Int. J. Heat Fluid Flow, 2001, vol. 22, pp. 509–518.

**[17]**Nuntadusit C., Wae-hayee M., Bunyajitradulya A., Eiamsa-ard S. Thermal Visualization on Surface with Transverse Perforated Ribs. Int. Commun. Heat Mass Transf., 2012, vol. 39, pp. 634–639.

**[18]**Huang K.D., Tzeng S.C., Jeng T.M., Wang J.R., Cheng S.Y., Tseng K.T. Experimental Study of Fluid Flow and Heat Transfer Characteristics in the Square Channel with a Perforation Baffle. Int. J. Heat Mass Transfer, 2008, vol. 35, pp. 1106–1112.

**[19]**Buchlin J.M. Convective Heat Transfer in a Channel with Perforated Ribs. Int. J. Therm. Sci., 2002, vol. 41, pp. 332–340.

**[20]**Karwa R., Maheshwari B.K., Karwa N. Experimental Study of Heat Transfer Enhancement in an Asymmetrically Heated Rectangular Duct with Perforated Baffles. Int. Commun. Heat Mass Transf., 2005, vol. 32, pp. 275–284.

**[21]**Jorgensen F.E. How to measure turbulence with hot-wire anemometers – a practical guide. Skovlunde, Dantec Dynamics, 2002, 73 p.

**[22]**Moffat R.J. Describing the Uncertainties in Experimental Results. Exp. Therm. Fluid Sci., 1988, vol. 1(1), pp. 3–17.

**[23]**Clauser, F.H. The Turbulent Boundary Layer. Adv. Appl. Mech., 1956, vol. 4, pp. 1–51.

**[24]**Kutateladze S.S., Leontiev A.I. Teplomassoobmen i trenie v turbulentnom pogranichnom sloe [Heat transfer, mass transfer, and friction in a turbulent boundary layer]. Moscow, Energiya Publ., 1972, 342 p.