【摘要】 针对斜齿螺旋扭带的制造困难,提出了一种自动清洗式传热强化新元件——旋流口椭圆齿平带,每个椭圆齿都是使平带自转的流体动力结构元素,平带两侧的旋流口使管内的部分液体形成螺旋线流,因而具有近似斜齿螺旋扭带那样能够在较低流速下自转、实现管内污垢在线自动清洗的性能.同时流体经过椭圆齿后产生的大量涡流、管内部分液体转变成的螺旋线流以及螺旋线流与轴向流线不断交错混合等三方面的综合作用,使管内对流传热得到强化.对椭圆齿的齿距、斜角和旋流口三个因素进行了试验研究,结果表明:旋流口椭圆齿平带在管内流速为0.5 m/s左右就能可靠旋转运行;相对于光滑螺旋扭带,旋流口椭圆齿平带的管内侧传热系数可提高171%;其在管内流速为0.625 m/s时的流体阻力为3.25 kPa/m,流体阻力在一般工程许可的范围内.因此,旋流口椭圆齿平带具有良好的综合性能,并且又容易制造,具有较高的工程应用价值.更多还原

【Abstract】 Due to the difficulty of manufacturing twisted tape with teeth,a new component,straight strip-insert with elliptical teeth and broken edge on both sides,which could automatically removed fouling and enhanced heat transfer,was put forward.Each tooth was a fluidic power structure element to drive the insert self-rotate.For the broken edge,part of the fluid in tubes formed spiral flow.Therefore,this straight strip could self-rotate at low flowing speed and remove the fouling on tube wall automatically just like twisted strip with oblique teeth.Meantime,the convection heat transfer was greatly enhanced because of the three factors: much eddy flow behind the elliptical teeth,fluid flow’s changing into spiral flow,combination and separation of spiral flow and axial flow.Experimental research was conducted on the three factors including elliptical teeth distance,teeth angle and broken edge.The results showed,comparing to twisted tape,this new insert could work reliably at the flow speed of 0.5 m/s in tube and make the heat transfer coefficient inside tubes increased by 171%.The flowing resistance was in the range of industrial permission,which equaled to 3.25 kPa/m when the flow velocity in tube was 0.625 m/s.Therefore,this strip had good comprehensive performance and could be manufactured easily;it had great significance to industrial application.更多还原