Experiments on Strouhal's Number

抄録

The frequency n of eddies generated behind a circular cylinder in fluid is expressed by the equation n=S(v/d), where v is the fluid velocity, d the diameter of circular cylinder and S Strouhal's number, which has been treated as the function of Reynold's number. Many inverstigators have experimented on the values of Strouhal's number between R₆≒3×10∼5×10⁵, but the values between. R₆≒2×10⁴∼1×10⁵ have not been obtained. The present authors have experimented on all of them between R₆≒6×10∼5×10⁵ by three devices with a high speed tunnel, a low speed tunnel and a water rotating vessel respectively and have made it clear that they take nearly a value of 0.18 between R₆=1×10⁴∼1×10⁵, suddenly increasing to 0.3∼0.6 at the point near the critical Reynold's number R_ec≒5×10⁵.