【摘要】 针对船舶减阻,论文采用主动喷射气体减阻方式,在国内循环水槽中首次开展大型平板在高雷诺数条件下喷射气体沿流程方向阻力分布特性及其减阻持续距离的试验研究,考察喷射气体减阻的3个阶段:气泡减阻阶段(bubble drag reduction,BDR),过渡阶段(transition),气层(膜)减阻阶段(air layer drag reduction,ALDR)。试验结果表明,气层(膜)减阻是非常有效及有应用前景的减阻方式。在形成有效气层时,较经济的气层名义厚度约为7~8 mm,在两侧设置50 mm气体逃逸挡板条件下,减阻持续距离可达9 m。根据试验测量结果,在较大气泡直径(毫米级)状态,浮力与升力(剪切力)的比值对气泡的运动扩散有较重要的影响。采用无量纲相似参数vg/u_τ~3可获取形成气层(ALDR)的临界气体流量曲线,为不同雷诺数下精确预报气体流量提供相似性分析的技术手段。更多还原

【Abstract】 This paper describes an active means of reducing friction drag by gas injection in a high Reynolds number flat-plate turbulent boundary layer. In model test, distribution of friction drag along the velocity direction and persistent distance were measured for gas injector boards with different sizes, numbers and spaces. There are three stages for friction drag reduction: bubble drag reduction(BDR), transition and air layer drag reduction(ALDR). The test results indicate that ALDR is a promising means for friction drag reduction, where economic nominal thickness of ALDR is about 7~8 mm, and maintained distance is up to 9 meters in the case of side clap-boards of 50 mm. When the bubble size is in the range of millimeters, the ratio of buoyancy-to-lift is important for bubble diffuser under the turbulent boundary layer. The parameter νg/u_t~3 is useful for describing critical gas flux of ALDR.更多还原