Drag reduction performance and mechanism of a thermally conductive elastic wall in internal flow

Types of thermally conductive elastic walls with different thicknesses were prepared to study the drag reduction performance among elastic and rigid walls. Nano graphene was used as a conductive filler, and viscoelasticity silicon rubber was used as the matrix. To study the performance of the walls, internal flow equipment with a testing system was designed based on differential pressure measurement. According to the experimental results, the thermally conductive elastic wall exhibited the most optimal drag reduction effect. The maximum drag reduction rate of the elastic wall reached 8.54%. At a flow speed of 1.5 m/s, the thermally conductive elastic wall reached a maximum drag reduction rate 1.17% higher than that of the elastic wall under the same condition. The thermally conductive elastic wall had two mechanisms. First, the elasticity deformation increased the boundary layer thickness and decreased the velocity gradient, reducing the shear force. Second, the heat produced by the elastic deformation of the thermally conductive elastic wall was conducted at the boundary layer and decreased the viscosity, resulting in drag reduction. The thermally conductive elastic wall should delay the aging process and increase the service life of fluid machinery. (c) 2017 Elsevier Ltd. All rights reserved.