Turbulence generators such as a 25.4 mm tall, 12.7 mm wide (W) and 0.1 mm thick rectangular flexible strip can provide a robust means of enhancing convective heat transfer. This wind-tunnel study aimed at uncovering the effect of freestream turbulence on heat convection enhancement of a flat surface by a flexible strip. The freestream turbulence was furnished by a 6 mm thick orificed perforated plate (OPP) with 57% perforation consisting of 38.1 mm diameter (D) holes. The OPP was installed at 10D, 13D and 16D upstream of the strip, to achieve 11%, 9% and 7% turbulence. The investigation was conducted at a Reynolds number based on the strip width of 6000. The convective heat transfer augmentation was analyzed in terms of Nusselt number with respect to the reference no-strip case (Nu/Nu₀). The flow turbulence was characterized with the help of a 3D hotwire probe. The freestream turbulence is found to diminish the flexible-strip induced Nu/Nu₀ significantly. This is principally because Nu₀ increases considerably with increasing freestream turbulence. It is of practical significance that the flexible strip always increases Nu, and this improvement is largest with respect to an otherwise ‘laminar’ freestream.

湍流发生器（例如25.4毫米高，12.7毫米宽（W）和0.1毫米厚的矩形柔性条）可以提供增强对流传热的强大方法。这项风洞研究的目的是揭示自由流湍流对柔性条带增强平面热对流的影响。自由流湍流由6 mm厚的穿孔板（OPP）提供，其穿孔率为57％，由38.1 mm的直径（D）孔组成。该OPP是安装在10 d，13 d和16 d在钢带的上游，实现11％，9％和7％的湍流。研究是基于条带宽度为6000的雷诺数进行的。对流传热增强是相对于参考无条纹情况（Nu / Nu ₀）的Nusselt数进行分析的。借助3D热线探针对流动湍流进行了表征。发现自由流湍流显着减小了柔性带引起的Nu / Nu ₀。这主要是因为Nu ₀随着自由流湍流的增加而显着增加。具有实际意义的是，柔性条带总是增加Nu，相对于其他“层状”自由流，此改进最大。