2) Consider air flow (at the film temperature, p=1.2 kg/m and u=2x105 Pa.s, k=0.026 W/m.K, Pr=0.7)...

   

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2) Consider air flow (at the film temperature, p=1.2 kg/m and u=2x105 Pa.s, k=0.026 W/m.K, Pr=0.7) around a cylinder with diameter of XX cm. The cylinder surface temperature is 10*XX more than the cylinder surface temperature. Free stream velocity is XX/20 m/s. Use Eq. 7.52 to evaluate Nusselt Number. Calculate heat flux at the surface (W/m). Some common correlations for external flow: Conditions Correlation Geometry 8 = 5x Re/2 -1/2 (7.19) Flat plate Laminar, T C=0.664 Re -112 (7.20) Flat plate Laminar, local, Ty Nu, 0.332 Rep (7.23) Flat plate Laminar, local, Ty, Pr 0.6 8,-8 Pr-1/3 (7.24) Flat plate Laminar, T Cx = 1.328 Re-1/2 (7.29) Flat plate Laminar, average, T Nu, -0.664 Re Prin (7.30) Flat plate Laminar, average, Ty, Pr 0.6 Nu, = 0.564 Pe (7.32) Flat plate Laminar, local, T, Pr 0.05, Pe, 100 C=0.0592 Res (7.34) Flat plate Turbulent, local, T,, Re, 10% 8 = 0.37xRe5 (7.35) Flat plate Turbulent, T,, Re, 10% Nu, -0.0296 Rep (7.36) Flat plate Turbulent, local, Ty, Re, 10, 0.6 Pr 60 C=0.074 Res 1742 Rez (7.40) Flat plate Mixed, average, T, Re,, = 5 x 10, Re = 10 ==== Nu, (0.037 Re5-871)Pr (7.38) Flat plate Mixed, average, T,, Re = 5 x 10, Re, 108, 0.6 Pr 60 Nu = C Re Pr (7.52) Cylinder Average, T, 0.4 Re, 4 10, (Table 7.2) Prz 0.7 Nup C Re Pr"(PriPr) (7.53) (Table 7.4) TABLE 7.2 Constants of Equation 7.52 for the circular cylinder in cross flow [11, 12] Average, T. Rep 10, 0.7 Pr 500 TABLE 7.4 Constants of Equation 7.53 for the circular cylinder in cross flow [17] Cylinder Rep C m Rep C m 0.4-4 0.989 0.330 4-40 0.911 0.385 1-40 0.75 0.4 40-4000 0.683 0.466 40-1000 0.51 0.5 4000-40,000 0.193 0.618 10-2 10 0.26 0.6 40,000-400,000 0.027 0.805 2 x 10-10 0.076 0.7 2) Consider air flow (at the film temperature, p=1.2 kg/m and u=2x105 Pa.s, k=0.026 W/m.K, Pr=0.7) around a cylinder with diameter of XX cm. The cylinder surface temperature is 10*XX more than the cylinder surface temperature. Free stream velocity is XX/20 m/s. Use Eq. 7.52 to evaluate Nusselt Number. Calculate heat flux at the surface (W/m). Some common correlations for external flow: Conditions Correlation Geometry 8 = 5x Re/2 -1/2 (7.19) Flat plate Laminar, T C=0.664 Re -112 (7.20) Flat plate Laminar, local, Ty Nu, 0.332 Rep (7.23) Flat plate Laminar, local, Ty, Pr 0.6 8,-8 Pr-1/3 (7.24) Flat plate Laminar, T Cx = 1.328 Re-1/2 (7.29) Flat plate Laminar, average, T Nu, -0.664 Re Prin (7.30) Flat plate Laminar, average, Ty, Pr 0.6 Nu, = 0.564 Pe (7.32) Flat plate Laminar, local, T, Pr 0.05, Pe, 100 C=0.0592 Res (7.34) Flat plate Turbulent, local, T,, Re, 10% 8 = 0.37xRe5 (7.35) Flat plate Turbulent, T,, Re, 10% Nu, -0.0296 Rep (7.36) Flat plate Turbulent, local, Ty, Re, 10, 0.6 Pr 60 C=0.074 Res 1742 Rez (7.40) Flat plate Mixed, average, T, Re,, = 5 x 10, Re = 10 ==== Nu, (0.037 Re5-871)Pr (7.38) Flat plate Mixed, average, T,, Re = 5 x 10, Re, 108, 0.6 Pr 60 Nu = C Re Pr (7.52) Cylinder Average, T, 0.4 Re, 4 10, (Table 7.2) Prz 0.7 Nup C Re Pr"(PriPr) (7.53) (Table 7.4) TABLE 7.2 Constants of Equation 7.52 for the circular cylinder in cross flow [11, 12] Average, T. Rep 10, 0.7 Pr 500 TABLE 7.4 Constants of Equation 7.53 for the circular cylinder in cross flow [17] Cylinder Rep C m Rep C m 0.4-4 0.989 0.330 4-40 0.911 0.385 1-40 0.75 0.4 40-4000 0.683 0.466 40-1000 0.51 0.5 4000-40,000 0.193 0.618 10-2 10 0.26 0.6 40,000-400,000 0.027 0.805 2 x 10-10 0.076 0.7

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A nice problem in heat transfer To solve this problem we need to use the correlation for the Nusselt ... View the full answer