气液两相绕流柱体时的涡街特性研究

A Study of Vortex Street Characteristicsin a Gas-liquid Two-phase Flow PassingAcrss a Triangular Cylinder

本文以水空气两相流体为工质，研究了两相流体横向冲刷准三角形柱体时的涡街生成特性．试验段管子内径５０ｍｍ，水流速度２．２０ｍ／ｓ－３．７４ｍ／ｓ截面含气率为０．０２－０．３．得出了两相流体中涡街发生频率，水流量和截面含气率三者之间的相互关系。

Vortex emission has been extensively studied in single phase liquid and gas flows.On the con-trary, while two-phase flows are more and more frequently encountered in practical applications.forinstance in nuclear, petroleum and chemical engineerings, very few experimental data are available onvortex emission in such flows.We present here an experimental study of vortex emission in vertical air-water upwaved two phaseflows. The obstacle geometry is an quasi-triangular cylinder. and the flow regime is bubble flow, orsometimes.low void fraction slug flow. The measurements were performed at room pressure and tem-perature,the liquid velocities vary from .20m/s to 3.74m/s, the void fraction is 0.1 to 0.4. theinner diameter of tested tube is 50mm. Two flow regimes were observed,for void fraction smallerthan 1 8 % vortex emission remained stable and its frequency sharply defined. above 1 8 % void frac-tion vortex emission became erratic, and for void fraction lager than 22%,the vortex emission fre-quency can not be defined. Relationships among the vortex street frequency. water flow rate and voidfraction are established. The vortex street was detected with temperature detector, computer was usedto collect and analyze the data.The obstacle thick is 10. 6mm. apex angle is 38°. width is 1 3.8mm. The width of the obstaclewas about 0.27 times the pipe diameter.this width/pipe diameter ratio has been closed because it pro-vided very strong vortex emission signals.