摘要
在矩形通道内布置一对斜截半椭圆柱面涡流发生器(高宽比h/b=1/2),通过改变斜边倾角α、来流攻角β、前沿间距S、布置方式以及顺列、错列两排涡流发生器研究不同工况下的换热和压降特性。试验雷诺数范围为Re=700～26800。结果表明,在试验条件下α=12°时的换热效果要好于α=20°,Re=1300时两者的最高局部对流换热系数分别比平直通道高19.7%和10.7%,Re=26800时分别为23.2%和18.33%。斜截半椭圆柱面涡流发生器(α=12°)的最优攻角为β=60o,最优前沿间距为S=20mm。当Re=26800,β=60°,S=20mm时的最高局部对流换热系数约比平直通道高23.2%,压力损失约比平直通道高33.7%。雷诺数较小时,由于回流滞止区的影响,布置两排涡流发生器后,换热效果反而弱于单排。随着雷诺数增大到4000,双排涡流发生器的换热效果要明显优于单排,Re=26800时,最高局部对流换热系数约比单排涡流发生器高14.4%,比平直通道高33.4%。通过试验得出斜截半椭圆柱面涡流发生器在β=60°,α=12°时的涡旋作用距离大约在250～300mm。
The heat transfer enhancement and pressure drop characteristics of a pair of oblique-cut semi-elliptic cylinder shell vortex generators（aspect ratio h/b= 1/2） in a rectangular channel are experimentally investigated by changing the elevation angle α,attack angle β,spacing of the leading-edges S,and the arrangement under various operating conditions.The performance of two rows of in-line and staggered arrayed vortex generators are also investigated.Experimental Reynolds number,Re,ranges from 700 to 26 800.The results indicate that under the present experimental conditions,the heat transfer enhancement of α = 12° is better than that of α = 20° with the highest local convective heat transfer coefficients 19.7% and 10.7% higher than that of the flat channel at Re = 1 300,and 23.2%,18.33% at Re = 26 800,respectively.The optimal attack angle and spacing of the leading-edges for oblique-cut semi-elliptic cylinder shell vortex generators（α = 12°） are β = 60° and S = 20 mm with the highest local heat transfer coefficient and the pressure drop about 23.2% and 33.7 % higher than the flat channel at Re = 26 800.Due to the effect of the wake region,the heat transfer enhancement of two rows is weaker than the single row at low Reynolds.As the Reynolds number increases up to 4 000,the heat transfer enhancement of two rows is better than the single row with the highest local heat transfer coefficient about 14.4% higher than the single row vortex generators and 33.4% higher than the flat-channel at Re = 26 800.In addition,the results show that the vortices acting distance of oblique-cut semi-elliptic cylinder shell vortex generator is approximately between 250mm and 300 mm at β = 60°,α = 12°.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2010年第16期162-169,共8页
Journal of Mechanical Engineering
基金
高等学校博士学科点专项科研基金(20070079018)
河北省自然科学基金(E2008001231)
北京市'供热
供燃气
通风及空调工程'重点实验室开放课题(KF200708)
电力青年科技创新(2008)资助项目
关键词
涡流发生器
强化换热
压降
矩形通道
试验研究
Vortex generator Heat transfer enhancement Pressure drop Rectangular channel Experimental investigation
