大型电站锅炉多组小屏绕流的数学模型

引入“旋涡层”概念，炉深方向沿前屏分布着旋涡层，薄板翼导流，炉内右半部分的旋涡层削弱网格涡的速度环量。旋转上升气流绕流前屏，在其表面和尾部分别形成附着涡和分离涡；采用镜像法处理炉膛固壁对涡运动的影响。考虑炉内大残旋网格涡的切向速度；附着涡、分离涡及镜像涡的诱导速度，首次建立了多组小屏绕流的数学模型，并对HG-2008/18．2-YM2型锅炉等温模型进行理论计算。计算表明：后屏入口的速度右侧高左侧低，右侧镜像附着涡和分离涡诱导的速度，使后屏入口右侧速度升高。六线涡量探针所测涡量场表明：炉内螺旋上升气流绕流薄板翼，在前屏尾部，确实产生了分离涡；且后屏入口速度场，也表现为右侧高左侧低，试验结果和理论计算定性吻合，验证了所建数学模型的合理性，为分析小屏尾部分离涡对水平烟道左右侧速度偏差的影响，提供了理论依据。

MATHEMATICAL MODEL ON FLOW AROUND MULTI-PLATEN IN THE TANGENTIALLY-FIRED FURNACE

The concept of vortex layer is cited. The vortex layer is distributed on front platen along depth of the furnace. Velocity circulation of grid vortex is reduced because of vortex layer. The multi-platen (front platen) is considered as a series of thin-plate airfoils. Because spiral up flow winds front platen, adhesive vortices are around surface of thin-plate airfoils and separated vortices are excited at tail of front platen. Mirror image vortices are produced in both sides of chamber because left or right wall exists. Considering induction velocity of various vortices, and tangential velocity of large grid vortex, a mathematical model that is used to resolve flow around multi-platen is firstly built and theoretically can be used to calculate the isothermal model of HG-2008-YM2 tangentially-fired furnace. The results of calculation show that the right inlet velocity at the rear platen is higher than the left one. The induction velocity produced by mirror image and separated vortices lead that the right velocity lifts at inlet of rear platen. Measurements of vorticity fields of flow around multi-platen made with six-sensor hot-wire probe show that the separated vortices really exist at tail of front platen because of flow around thin-plate airfoils. Theoretical results are identical with the measurement value qualitatively. It provides theoretical foundation for the influence of flow around multi-platen on velocity imbalance.