CC型通道波纹相对节距对流动与换热特性的影响

在三维空间上对CC(Crosscorrugated)型原表面换热器通道内流体的流动与换热特性进行了数值模拟。通道表面为正弦型曲面,上、下波纹板交错角固定为60°,节距与高度的比P/H取值范围为1.5~4.0。结果表明:当雷诺数Re约大于100后,各通道在中平面处产生的旋涡所形成的螺旋型自由剪切层开始变得不稳定,加强了流体间的混合;Re在约100~500的范围内,随P/H的增大,阻力系数f和平均努谢尔特数Nu增加,当Re继续增加(约大于2000)时,以P/H=2.2为界,P/H对f及Nu的影响呈相反的趋势变化;在适中的Re范围内,不同表面均可获得较好的表面性能,且随P/H的增大,获得最佳表面性能的Re减小。图12参8

Effects of Pitch-to-Height Ratio on Flow and Heat Transfer Characteristics in Cross-Corrugation Passages

An investigation on the characteristics of flow and heat transfer was conducted using three dimensional numerical simulation for heat exchanger passages which bear sine-wave and crossed-corrugated primary geometry. The corrugation angle of the neighboring plates was fixed at 60 deg, the ratio of pitch-to-height P/H was between 1.5 and 4.0. The results illustrated that the spiral shear layer at midplane caused due to vortice became instability when Re(Reynolds Number) exceeded 100, so that the mixing among fluid was promoted. The friction factor and the Nu(mean Nusselt Number) increased with increasing P/H when Re was between 100 and 500, and as continually increasing Re(Re>2000), the effect of the P/H on f and Nu behaved the reverse change trend with the division point of P/H=2.2. The preferable surface performances can be attained for all geometries within the range of moderate Re, and the Re corresponding to the optimal surface performances decreased with increasing P/H. Figs 12 and refs 8.