带流线型纵向涡发生器的曲线管道内流体流动与传热研究

The effective influence distance of the vortices are shorter in the curve channel than in the straight channel, which results in the installation density of pin-, wing- and winglet-type vortex generators is larger and so does the flow resistance. For the shortcomings mentioned above, streamlined longitudinal vortex generators will be used to enhance heat transfer performance of curve channel in this project. Using streamlined longitudinal vortex generators is expected to bring smaller flow resistance because streamlined structure helps to reduce the pressure drag and friction resistance. This project intends to research fluid flow, heat transfer and resistance characteristics of the curve channel with the streamlined longitudinal vortex generators by experimental and numerical simulation method. The structure and the synergy of velocity field and temperature field will be investigated. The influence of such parameters as the geometry, size, location and quantity of the streamlined longitudinal vortex generators and the curvature, torsion, shape and size of the cross section of the curve channel on the fluid flow and heat transfer performance will be examined. Based on the results, the resistance characteristics and heat transfer performance of the curve channel with streamlined longitudinal vortex generators will be quantitatively described by mathematical model. The mechanism of heat transfer enhancement of streamlined longitudinal vortex generators will be revealed. The research results of this project can provide a reasonable basis for the design of an industrial heat exchanger which is associated with the project, such as the shell side of heat exchanger (or the cooling jacket of a reactor) enhanced by helical baffle and streamlined longitudinal vortex generators. The conclusion on heat transfer enhancement mechanism drawn from this project will contribute to the development of novel heat exchanger.

针对柱型和翅翼型涡发生器强化曲线管道传热时作用距离短，需要安装密度大，从而导致较大阻力的缺点，本项目提出采用流线型纵向涡发生器来强化曲线管道传热。流线型结构有助于减少压差阻力和摩擦阻力，因此利用流线型纵向涡发生器强化传热可望降低流动阻力。本项目拟采用实验和数值模拟方法研究带流线型纵向涡发生器的曲线管道内流体流动和传热及阻力特性；考察速度场和温度场的结构及其协同性；考察流线型纵向涡发生器结构、尺寸、安装位置、数量以及曲线管道曲率、挠率、截面形状及尺寸等参数对流体流动和传热及阻力特性的影响，得到其基本规律；建立定量描述带流线型纵向涡发生器的曲线管道传热及阻力特性的数学模型；揭示流线型纵向涡发生器强化传热机理。研究结果可为与本项目相关的换热设备，如螺旋导流板与流线型纵向涡发生器复合强化的换热器壳侧（或反应器夹套）的合理设计提供依据，项目在强化传热机理方面取得的结论将有助于指导新型换热器的开发。

本项目针对传统翅翼型纵向涡发生器在强化传热同时产生的阻力较大的缺点，提出了采用流线型设计的涡发生器来强化曲线管道传热。项目研究了几种结构的流线型涡发生器，包括半圆型、切线弧型、样条曲线型的强化传热特性和阻力特性，并与传统强化效果比较好的三角翼型纵向涡发生器的强化传热特性和阻力特性进行了比较。对流线型纵向涡发生器的尺寸、数量和安装角度等影响传热特性和阻力特性的因素进行了考察，并得到了其影响规律。对不同结构的纵向涡发生器的传热特性和阻力特性进行了数学关联，得到了可用于指导优化和设计的数学模型。应用场协同原理，对流线型纵向涡发生器的强化传热机理和减阻机理进行了分析。.项目研究结果表明，流线型纵向涡发生器的综合传热效果优于传统三角翼型纵向涡发生器；在所研究的几种流线型涡发生器中，切线弧型的纵向涡发生器的综合传热性能优于半圆型和样条曲线型的纵向涡发生器；流线型纵向涡发生器的尺寸、数量和安装角度对传热和阻力影响显著；流线型纵向涡发生器的强化传热机理在于其提高了速度场与温度场之间的协同性，而其减阻机理在于其提高了速度场与压力场之间的协同性。.在特定的结构中，流线型纵向涡发生器可将传热系数提高46%；与三角翼型纵向涡发生器相比，流线型纵向涡发生器可以将流动阻力降低21%。传统三角翼型涡发生器，截面内速度场与压力场之间的协同角大于90o，而流线型涡发生器的协同角小于90o。证明了流线型涡发生器的减阻机理在于其提高了速度场与压力场之间的协同性。.本项目提出了采用流线型纵向涡发生器强化曲线管道内传热的新型强化传热方法，该方法具有强化传热效果好、流动阻力小的优点。本项目对曲线管道内绕物流动的流场特性、传热特性及流线型涡发生器强化传热机理和减阻机理的研究，丰富了流体力学和传热学的内容，所取得的结果可指导纵向涡与螺旋片复合强化的换热器的设计，所取得的结论可指导强化传热新技术的开发。