Numerical study on the wave pattern characteristic of air layer in cavity and the effects of multiple influence factors  

作　　者：Xiao-song Zhang Xue-qin Ji Lei-qiang Chen Li-jin Gao Hong-bo Huang Fang-wen Hong 

机构地区：[1]CSSC Shanghai Marine Energy Saving Technology Co.Ltd.,Shanghai,200011,China [2]China Ship Scientific Research Center Shanghai Branch,Shanghai,200011,China [3]China Ship Scientific Research Center,Wuxi,214082,China [4]School of Naval Architecture,Ocean and Civil Engineering,State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University,Shanghai,200240,China

出　　处：《Journal of Hydrodynamics》2023年第5期923-941,共19页水动力学研究与进展B辑（英文版）

基　　金：Project supported by the Ministry of Industry and Information Technology of China(Project No.CB01N20-05).

摘　　要：Air-layer drag reduction (ALDR) technology for ship energy saving is getting more and more attention in recent years because of the outstanding drag reduction effect. In order to promote practical application, it is necessary to fully understand the two phase flow characteristics of the air layer. Recent experimental studies have shown that the surface of the air layer presents wave pattern, which has an important influence on its damage risk. However, it is difficult to measure the wave pattern quantificationally due to the interference of equipment. The main goal of the present paper is to investigate the wave pattern characteristic of air layer in cavity using numerical simulation method. On this basis, the effect of flow and geometric influence factors are discussed to understand the key control conditions. A computational fluid dynamics (CFD) numerical method based on Reynolds averaged Navier-Stokes (RANS) equations and volume of fluid (VOF) interface capturing method is established, and has been successfully applied in the simulation of air layer wave pattern. Both 2-D and 3-D simulations are carried out, aiming at analyzing air-water interface flow and vortex flow directly. Based on the simulation results, several important conclusions about the mechanism of air layer wave pattern can be obtained. Firstly, it is found to be an inherent characteristic that the wave height of the upstream air layer is higher than that of the downstream. The extremely high wave peak is easy to contact with the flat plate, leading to the breakup of air layer and a “central blank area” phenomenon. With the help of flow analysis, it is found that this characteristic is mainly caused by the strong counterclockwise vortex behind the bow wedge block. Secondly, the air layer stability is reduced with the increase of water flow velocity by affecting the wave height. There is a saturation point of air flow rate to reach maximum thickness of air layer. Thirdly, cavity configuration has obvious influence on air layer stability by in

关 键 词：Air layer drag reduction wave pattern of air-water interface numerical simulation multiple influence factors vortex flow fields 

分 类 号：O35[理学—流体力学]