在使用节段模型的风洞试验中,端板或补偿模型常被用于减小端部效应的影响。为了明确端板、补偿模型对斜拉索节段模型气动特性测试结果的影响,通过刚性模型测力试验的方法,研究了补偿模型安装间距对模型阻力系数的影响;通过刚性模型测力、测压试验的方法,分析了端板尺寸对模型阻力系数、风压系数的影响。研究结果表明:当模型长细比小于18时,补偿模型这种措施不能消除端部效应的影响;端部效应,不仅对端部附近的风压分布有影响,对中间位置的影响也不容忽视;端板尺寸较小时不能保证中间位置的二维流动;随着端板尺寸增大,阻力系数逐渐增大,当端板尺寸大于4倍模型直径后,阻力系数不再明显改变。
It is commonly accepted that end plates or compensation models should be used to reduce the influence of both ends on the cylinder in wind tunnel experiments. Despite the widespread use of end plates and compensation models, there is only limited information available regarding the specific design criteria to be met. Through wind tunnel tests, the effects of compensation models on drag coefficients are studied; the effects of end plates on wind pressure as well as drag coefficients are also discussed. The results indicate that: when the aspect ratio of the model is less than 18, the flow around the model is not nominally two-dimensional flow; the free ends of cylinder have impact on wind pressure distribution not only in the vicinity of the ends but also on the middle part. The small end plates are useless to keep the nominally two-dimensional flow on the middle. End plates can increase the drag force of the cylinder. The drag force tends to be a constant value for end plates with a diameter of larger than 4 times the diameter of the testing model.