火电厂直接空冷系统风洞热效应模拟实验研究

Simulation and Experimental Study of the Wind-tunnel Thermal Effect of a Directly Air-cooled System in a Thermal Power Plant

将空冷凝汽器模型内通恒定温度的热水构成热循环系统,在低速风洞中首次同时模拟了空气动力学、轴流风机的强迫对流以及热空气的浮力效应在内的复杂流动与热动力学耦合问题。提出影响空冷凝汽器散热效果的回流率的概念,探求来流条件的变化对空冷岛底部平均回流率的影响,并进行相应的PIV测速实验。结果发现,空冷岛底部平均回流率随着风速的增大而增大;不同风速的条件下,空冷岛底部平均回流率随风向角的变化趋势基本一致,并且风向为西风、西南风和西北风附近时空冷岛底部平均回流率较大;增加挡风墙高度可以降低空冷岛底部平均回流率,并且风墙高度为14.64m时平均回流率最小。

With constant-temperature hot water passing through an air-cooled condenser model to form a thermal circulation system,simulated simultaneously for the first time in a low speed wind tunnel was the coupling of complex flow with thermodynamics,including aerodynamics,forced convection in an axial compressor and buoyant effect of hot air.A concept of return flow rate that influences the heat dispersion effectiveness of the air-cooled condenser was presented and the influence of the change of coming flows on the averaged return flow rate at the bottom of the air-cooled island explored.In addition,PIV (Particle Image Velocimetry) velocity-measuring experiments were performed accordingly.It has been found that the average return-flow rate in question increases with an increase in air speed,assumes a basically identical variation tendency with the change in air flow direction at different air speeds.The above-mentioned return flow rate is comparatively large when the air flow direction is approximately west,southwest and northwest.The average return flow rate in question will decrease with an increase of the height of the windbreak wall and atttains a minimum value when the windbreak wall is 14.64 m tall.