串列三圆柱的脉动气动力特性试验研究

Tests for fluctuating aerodynamic force characteristics of three cylinders in series

采用刚性模型测压风洞试验的方法研究了不同间距下串列三圆柱的脉动气动力特性,并与单圆柱和串列双圆柱的结果进行了对比。试验雷诺数以及间距比L/D(相邻圆柱中心距与单圆柱的直径之比)分别为3.4×10^(4)和1.212.0。研究结果发现,与串列双圆柱类似,串列三圆柱上游和中游圆柱的临界间距比(L/D)cr=3.54.0。在临界间距比附近,脉动气动力系数突升至最大值。串列三圆柱下游圆柱表现出两个临界间距比,分别为(L/D)cr1=2.02.5和(L/D)cr2=3.54.0。脉动气动力系数在临界间距比(L/D)cr1附近突升至最大值,而在临界间距比(L/D)cr2附近发生突降现象。气动干扰对串列三圆柱斯托罗哈数的影响表现为减小效应,与串列双圆柱相比,这种减小效应在L/D<(L/D)cr时更明显。

Here, fluctuating aerodynamic force characteristics of three cylinders in series with different spacings were studied by using the method of rigid model pressure measurement wind tunnel tests, and the results were compared with those of single cylinder and double-cylinder in series. The test Reynolds number and spacing ratio L/D, i.e., the ratio of center distance between adjacent cylinders to diameter of single cylinder, were 3.4×10^(4) and 1.2-12.0, respectively. The results showed that for three cylinders in series, critical spacing ratio(L/D)cr of its upstream cylinder and that of midstream cylinder are 3.5-4.0, similar to those for double-cylinder in series;near the critical spacing ratio, fluctuating aerodynamic force coefficient suddenly rises to the maximum value;there are two critical spacing ratios for the downstream cylinder of three cylinders in series, they are(L/D)cr1= 2.0-2.5 and(L/D)cr2=3.5-4.0;fluctuating aerodynamic force coefficient suddenly rises to the maximum value near the critical spacing ratio(L/D)cr1, but drops sharply near the critical spacing ratio(L/D)cr2;the influence of aerodynamic interference on Strouhal number of three cylinders in series is presented as a reducing effect, it is more obvious when L/D<(L/D)cr compared with two-cylinder in series.