The particle image velocimetry (PIV) experiments are carried out to qualitative and quantitative study the flow field dynamic characteristics for different slit cylinders in order to reveal the influence of the Re, the slit position, the incline angle and width of the slit on the overall flow characteristics. The transient flow field, the time-averaged flow field and the Sr are obtained and the detailed overall flow structures and its transformation disciplines are studied. The results show that the interactions of the shedding vortex and the circumflux around the cylinder surface induce the blow-suction effect of the 120° and 180° slits, which makes the wake shedding vortex coupling happen significantly earlier. The 240° slit is close to the cylinder trailing edge so that the flow separation already happens before the fluid reach the slit, which fails to generate the effective blow-suction effect. The wake flow resistances for the 120° and 180° slit cylinders are higher because the motion trajectory amplitudes of shedding vortex are higher than that of the basic and 240° types. Sr values for the slit cylinder with α=180° and s/d=0.15 (α is the slit angle, s is the gap width, d is the cylinder diameter) are in the range of 0.218～0.225, which exhibits the strongest linear stability.
ZHU Rui,LI Shang,CHEN Ziyu,LIU Jinsheng,BAO Feng,LIU Zhirong
. Flow Field Dynamic Characteristics of Slit Cylinders[J]. Journal of Shanghai Jiaotong University, 2019
, 53(10)
: 1238
-1248
.
DOI: 10.16183/j.cnki.jsjtu.2019.99.002
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