INFLUENCE OF END CONDITIONS ON AERODYNAMIC FORCE OF SECTION MODELS FOR STAY-CABLES

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.