液体横掠热圆柱体时旋涡脱落的频谱分析

Heat effect on vortex shedding frequency spectrum on heated circular cylinder in liquid cross flow

引言流体（液体）横掠柱体时的工况是许多工业设备特别是换热器工作的主要工况.在这种工况下,流体横掠柱体的旋涡脱落特性、流动参数的分布、柱体受力及流动阻力等均是设备运行和设计的关键问题.而这些问题均源自流体横掠柱体时旋涡的脱落,因此,对流体横掠柱体旋涡脱落特性特别是其频谱特性的研究,对设备的高效节能、安全和稳定运行有重要意义.

The vortex shedding frequency spectrum characteristics on a heated circular cylinder in water cross flow was investigated experimentally. Heating changed the Fourier transform frequency spectrum energy of vortex shedding signal. The effect of heat varied with Reynolds number and there existed a critical value ReL, about 8.84 × 10^4 in the test condition. If the flow Reynolds number was less than ReL, the effect of heat on the Fourier transform frequency spectrum peak value of vortex shedding signal was small, and if the flow Reynolds number was larger than ReL, the effect of heat would be larger. When the flow Reynolds number was larger than ReL, heating reduced the Fourier transform frequency spectrum peak value reduce by about 30%. The phenomenon made the vortex shedding unstable and destroyed the Karmen vortex in the wake under some condition, and resonance was induced easily. Generally it arised if the flow Reynolds number be changed but the cylindor undeated.