Exploring feasibility of small wind tunnel suitable for experiments on riblets drag reduction

Experiments on riblets reduction require that the wind speed should be low and the turbulence intensity should be high. Having had long experience in small wind tunnel testing in general, we believe we are fairly well qualified to explore special purpose small wind tunnel testing for riblets drag reduction. Fig. 1 in the full paper shows the block diagram of the special purpose wind tunnel with a developing section as long as 2450 mm developed by us during our exploration. Section 2 details the special requirements on experimental flow field suitable for riblets drag reuction. Test results are presented in Figs. 4 through 7. These results show preliminarily that: (1) the allowable lowest wind speed can be reduced from 6m/s to 4m/s; (2) the boundary layer thickness can be increased from less than 20 mm to more than 50 mm; (3) the thickness of near-wall layer, including the viscous sublayer and the buffer zone, can be increased from about 2 mm to 5 mm.