|
| ||
|
|
||
Boundary Layer Theory (boundary + layer_theory)
Selected AbstractsFilm boiling heat transfer around a vertical finite-length cylinder with a convex hemispherical bottomHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2010Takashi Yamada Abstract The film boiling heat transfer around a vertical silver cylinder with a convex hemispherical bottom was investigated experimentally in quiescent water at atmospheric pressure. The experiments have been carried out using a quenching method. The diameter and length of the test cylinder are 32 mm and 48 mm, respectively. The test cylinder was heated to about 600 °C in an electric furnace and then cooled in saturated or subcooled water with an immersion depth of about 100 mm. The degree of liquid subcooling was varied from 0 K to 30 K. The analytical solutions for saturated and subcooled boiling are obtained by applying a two-phase boundary layer theory for vapor film with a smooth interface. The experimental data correlates within ±15% based on the proposed prediction method. Also, the lower limit of film boiling was examined in terms of wall heat flux and degree of superheating. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20289 [source] Estimation of agitator flow shear rateAICHE JOURNAL, Issue 7 2006Jie Wu Abstract Laboratory laser Doppler velocimetry (LDV) measurements were conducted to measure the shear rate coefficient KS of a range of impellers. Equations correlating KS with NQ (flow number) are provided for axial flow and radial flow impellers. Theoretical formulations based on the classic boundary layer theory are developed to estimate the shear rate at the blade surface. Calculations show that the shear rates at the blade surface are many orders of magnitude higher than those in the flow at the impeller outlet. The software code XFOIL was used to illustrate typical distributions of the shear rates along the blade surfaces. Effects of viscosity, non-Newtonian shear-thinning index, agitator design, and scale-up on shear rates are illustrated. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Hybrid, numerical solutions, for three-dimensional, compressible Navier-Stokes layerPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009A. NastaseArticle first published online: 5 MAR 2010 The author proposes new hybrid solutions for the three-dimensional, compressible Navier-Stokes layer (NSL) over a flying configuration (FC), which use the analytical potential solutions, of the same FC, two times, namely: to reinforce the numerical solutions by multiplying them with these analytical solutions and as outer flow (instead of the parallel flow, used by Prandtl in his boundary layer theory). These hybrid solutions fulfill the last behavior, have correct jumps along the singular lines (like subsonic leading edges, junction lines wing-fuselage, etc.), are split, accurate and rapid convergent. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Theory from Wind Tunnels: Empirical Roots of Twentieth Century Fluid DynamicsCENTAURUS, Issue 3 2008Michael Eckert Abstract Wind tunnels became major data-gathering devices for aeronautical engineering. They were indispensible for the design of airships and airplanes (and later also for optimizing the aerodynamic behavior of cars, trains, buildings and bridges). It is not astonishing, therefore, that theoretical concepts of fluid dynamics, too, emerged in close relation to wind tunnel testing. As the scope of fluid dynamics broadened after the Second World War, its roots in aeronautical engineering became obscured. I focus on the relation of the empirical and the formal in boundary layer theory, turbulence research, and gas dynamics. It is rarely remembered that it was in the wind tunnel where the empirical roots of these fields of 20th century fluid dynamics grew in close context with problems of aeronautical engineering. [source] | ||||||||||