涂层低表面能各分量降低流体噪声的试验研究

Experimental Study on the Reduction of Flow Noise Dueto Low Surface Energy Coating

水下航行体在高速运动时，由于物体和流体的相互作用，边界层中产生了速度和压力脉动而形成了流体噪声。针对低表面能涂层改变流体边界层的状态，考察了其在水洞中的降噪效果。涂层表面具有很好的疏水性和低的表面能色散分量与水相互作用力分量，使边界层增厚，降低由于壁面与流体界面的作用所产生的偶极子声源，从而达到降低流体噪声的效果。

Acoustic communication through the water medium is greatly handicapped by the noise produced by the moving vehicle and its machinery. At high speeds, the flow noise seems to mask all other components of noise. This study presents a first attempt to predict the levels of the boundary layer noise and noise produced by a coating composed of low surface energy as a function of the flow speed and the noise frequency on the basis of the results obtained by flow noise experiment performed with a rotating cylinder in a water tunnel. We investigate the tensile strength of the bond between water and coating materials. The results are compared with that measured previously with an Al alloy model. Large difference is found between Al model and that covered with low surface energy coating. The coating model contributed to its low dispersive and polar components of surface energy by decreasing bond between water and coating and increasing the boundary layer thickness, thus, it decreases the flow noise.