Abstract

Efforts were made to examine the effect of textile roughness for the reduction of aerodynamic drag experienced on a cyclist model. First of all, flow visualization experiments were conducted in a water channel with a 1/5 scale cyclist model to identify the flow separation lines on the contoured surface. Subsequently, based on the information learned, the idea of delaying flow separation on the model surface was implemented by means of sport suits. Seven sport suits featuring different textile materials and local roughness patterns were tested on a full-scale cyclist model in wind tunnel experiments, in addition to a reference case without a sport suit. From the C_D data deduced, we identified a critical condition in most of the cases studied, featuring a least drag coefficient occurred at a Reynolds number within the flow speed range studied. For the best case found, the drag coefficient is amounted 7.5% less than that of the reference case at the same Reynolds number. Furthermore, the C_p and C_prms values reduced from the pressure measurements on the cyclist model with the sport suits unveil a trend that the reduction of drag actually infers the retreat of the local flow separation lines toward the rear side of the body accompanied with less severe the flow unsteadiness.

摘要

已努力检查织物粗糙度对减少骑自行车者模型所经历的空气动力阻力的影响。首先，在具有 1/5 比例自行车模型的水道中进行流动可视化实验，以识别轮廓表面上的流动分离线。随后，根据了解到的信息，通过运动服实现了模型表面延迟流动分离的想法。除了没有运动服的参考案例外，七套具有不同纺织材料和局部粗糙图案的运动服在风洞实验中的全尺寸自行车模型上进行了测试。从_光盘_根据推断的数据，我们在所研究的大多数案例中确定了一个临界条件，其特点是在所研究的流速范围内的雷诺数处出现的阻力系数最小。对于找到的最佳情况，在相同雷诺数下，阻力系数比参考情况低 7.5%。此外，从穿着运动服的自行车模型上的压力测量中降低的C _p和C _prms值揭示了一种趋势，即阻力的减少实际上推断出局部流动分离线向身体后侧的后退，同时伴随着更少的阻力。严重的流动不稳定。