气泡高速艇艇底气穴形态及减阻机理研究

Study on high-speed air cavity craft form and mechanism of resistance reduction

为了揭示高速艇气层作用下的艇底流场特性及气穴减阻机理,基于VOF模型建立了气泡高速艇粘性兴波流场数值计算模型,分析了气穴形态、艇底压力及艇体阻力的变化规律,初步分析了气穴减阻机理,计算结果得到了模型试验的验证.研究结果表明:向艇底饱和喷气可形成稳定的大气穴,气穴厚度沿艇长方向逐渐减小;航速较低时气体从气腔中部的舷侧溢出,航速增加气穴向后延伸至艇尾,从气腔尾部两侧离开艇体;未喷气时,在气腔首部形成一个局部负压区;饱和喷气后,气穴内部变为等压腔体;气穴主要通过减少湿表面积降低摩擦阻力,对剩余阻力的影响不大.

In an effort to understand and reveal the viscous flow characteristics of an artificial air cavity mechanism of resistance reduction, a numerical model for calculating viscous wave-making flow field of and its a highspeed air cavity craft was constructed by utilizing a volume of fluid （VOF） muhiphase method. The air cavity shapes, bottom pressure and hull drag at zero and saturation air flow rate were investigated, and the mechanism of resistance reduction by air cavity was initially analyzed. The validities of the research were confirmed by the experi- mental data findings. The findings indicate that a big and steady air cavity was obtained by injecting air into artifi- cial hollow until the air is saturated, allowing the thickness to decrease gradually from the hollow head to the stem. As the hull moves at a low speed, air leaks from the ship side of the hollow mid and as the hull speeds up, the air- cavity extends backward to stern and leaves the hull from the two sides of hollow end. The pressure of the artificial hollow head decreases to a negative level if air flow rate is zero, but increases to a positive value if air flow is saturated, and the air cavity is in an isotonic body. As the air cavity primarily reduces friction resistance by decreasing the wet areas, there is little effect on the residual resistance.