Numerically and Experimentally Investigated Turbulent Flow Structure Past a Single “Trench”

• Main Authors: V. N. Afanas'ev, A. V. Nedaivozov, P. A. Semenev, K. Dehai
• Format: Article
• Language: Russian
• Published: MGTU im. N.È. Baumana 2016-01-01
• Series: Nauka i Obrazovanie
• Subjects: experimental and numerical investigation; boundary layer; turbulence; intensification of heat ex-change; trench
• Online Access: http://technomag.edu.ru/jour/article/view/30

<p>The paper presents results of experimental and numerical investigation of hydrodynamics and heat exchange with transversal flow past a two-dimensional trench without separation. The trench is placed on the flat plate and heated according to the law of qw=const. For experimentation a subsonic low-turbulent open-type aerodynamic tunnel was used. Mean velocity and temperature profiles have been obtained experimentally in different sections of tunnel above the single transversal cylindrical trench (stream-wise size s=37.5 mm, depth h=2.5 mm, h/s=0.067) with an external flow velocity of 18 m/s. Incompressible two-dimensional RANS (Reynolds Averaged Navier-Stokes equations) approach with two-parametrical k-ɛ and k-ω (MSST) turbulence models has been used in ANSYS FlUENT computational research.</p><p>The paper explores an impact of trench shape and geometry on the structure, turbulent boundary layer, drag friction, heat exchange and pressure on a streamlined surface.</p><p>It has been shown that calculations with k-<span style="font-family: 'Times New Roman', serif;"><span lang="ru-RU">ε </span></span>turbulence model constitute a match with experimental data. Thus, k-<span style="font-family: 'Times New Roman', serif;"><span lang="ru-RU">ε </span></span>turbulence model should be used for the low turbulent (ɛ &lt; 1%) and low-Reynolds flow calculation and both k-<span style="font-family: 'Times New Roman', serif;"><span lang="ru-RU">ε </span></span>and k- ω (MSST) turbulence models could be used for the high-turbulent (ɛ &gt; 2%) flow calculations. Surface profiling with a system of transversal trenches leads to increasing heat-transfer coefficient without raising surface drag friction.</p><p>The influence of different geometries of trench shapes on the heat transfer intensity has been numerically simulated. It has been revealed that in comparison with flat plate trenches with greater inlet angle have lower pressure losses and drag coefficient and substantially higher heattransfer coefficient.</p>