METHOD FOR ANALYZING FRICTION REDUCTION EFFECTS OF BUBBLES IN FRICTION-REDUCING SHIP

摘要

A method of more accurately analyzing the effect of reducing frictional resistance of the hull surface by bubbles is provided. The time constant T of bubbles and the turbulence of the flow field based on the drag force Δ R_v acting on the bubbles derived from the motion of the bubbles in the streamline direction (x direction) of the flow field on the hull surface and in the vertical direction (y direction) with respect to the hull wall surface. according to the definition of a large high frequency band than the product of the frequency ω _L 1, to obtain the reduction τ _t of the shear stress due to the intervention of the air bubbles, the art to the reduction of the shear stress assumed to have occurred by a decrease in chapter mixture, bubble diameter d_b The constant κ ₁ of the wall law in the presence of bubbles is obtained, and the relationship between the constant κ ₁ of the wall law in the presence of bubbles and the local frictional resistance coefficient C_f , and in the absence of bubbles Based on the relationship between the constant law κ of the wall law and the local frictional resistance coefficient C_f0 , an analysis value of the frictional resistance reduction ratio C_f/ C_f0 in the high frequency band is obtained.