The analysis of flow around a cylinder under free convection conditions

• Autorzy: Błaszczuk A. , Nowak W.
• Języki publikacji: EN

Abstrakty

EN

The article describes the application of the optical gradient technique to the analysis of development of the thermal boundary layer. This analysis was carried out using a modified schlieren system. The modifications made to the optical measuring system made it possible to extend the measuring range of the testing beam with a simultaneous reduction of the measuring system's susceptibility to misalignment. The coherent light source was an He-Ne laser of a power of 25 mW. Recording of the distribution of the information carrier's optical density around the experimental model was conducted using a CCD matrix coupled with an image acquisition card. The experimental model was a horizontal copper cylinder. The measurements of convective heat transfer were carried out for different thermal conditions (470, 410 and 350 K) of the cylinder surface. The obtained results of experimental analysis have been approximated with the exponential relationship NUD = C(Ra).

Słowa kluczowe

EN

thermal boundary layer; heat transfer coefficient; schlieren technique

PL

termiczna warstwa przyścienna; transport ciepła

• Wydawca: Wydawnictwo Politechniki Częstochowskiej
• Czasopismo: Turbulence : international journal
• Rocznik: 2007
• Tom: Vol. 12
• Strony: 31--41
• Opis fizyczny: Bibliogr. 9 poz., rys., tab.

Twórcy

autor

Błaszczuk A.

autor

Nowak W.

• Częstochowa University of Technology, Faculty of Enviromental Protection and Engineering, ul J. H. Dąbrowskiego 73, 42-200 Częstochowa, Poland,

Bibliografia

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• [2] Settles G. S.: Schlieren and Shadowgraph Techniques. Visualizing Phenomena in Transparent Media. Springer-Verlag, Berlin 2001.
• [3] Merzkirch W.: Colour Schlieren Optics - A Review of Techniques and Applications, Flow Visualization. II ed. G. S. Settles. Hemisphere, Washington D.C. 1982, 749-759.
• [4] Shaker Ch., Nirala A. K.: A review on refractive index and temperature profile measurement using laser-based interferometric techniques. Optics and Laser in Engineering 1999, 31,6, 455-491.
• [5] Tanda G., Devia F.: Application of a schlieren technique to heat transfer measurements in free-convection. Experiments in Fluid 1998, 24. 285-290.
• [6] Błaszczuk A., Mirek P., Nowak W.: The measurement of natural convection by means of modified Schlieren technique. The 4th International Conference on Transport Phenomena in Multiphase Systems, Heat 2005, 193-200.
• [7] Błaszczuk A., Mirek P.: Experimental investigation of the convective heat transfer around a perpendicular plate by means of flow Visualization techniques. Archives of Thermodynamics 2004,25, 73-86.
• [8] Sparrow E. M., Gregg J. L.: The variable fluid property problem of free convection. ASME Journal of Heat Transfer 1958, 80, 879-886.
• [9] Wiśniewski S., Wiśniewski T. S.: Wymiana ciepła. WNT, Warszawa 2000.