直、斜孔排气对航行体绕流流动影响:Part 2流体动力特性

Effect of Straight or Inclined Hole Exhaust on Flow Around Underwater Vehicle:Part 2-Hydrodynamic Characteristics

数值研究了直、斜孔排气对采用等压排气技术的水下垂直运动航行体绕流流场特性的影响。结果表明,排气孔附近及其下游流场可分为上游高压区、后缘的过膨胀-压缩区、下游近似等压区、膜尾处的逆压及顺压梯度区等五个区域;等压区范围与气膜的气相区、混合相区重合,分别通过气相区内气体顺流速度降低、混合相区内流体逆流速度降低而得到等压特性;斜孔排气时的水流与气流间相互作用减弱,排气速度及其轴向分量、流量显著增加,等压气膜形成速度、影响范围大幅提高。

Numerical study was conducted to investigated the effect of straight or inclined hole exhaust on the hydrodynamic characteristics of an underwater vehicle with vertical movement when pressure-equalizing exhaust technique was applied.The results show that the flow field near and downstream of the exhaust hole can be categorized into five parts：the high-pressure region,the over-expansion-contraction region,the approximate pressure-equalizing region,the adverse and the favorable pressure gradient regions.The pressure-equalizing region overlaps both air phase zone and mixed phase zone,and its pressure-equalizing characteristics is obtained through the downstream velocity reduction of air in the air phase zone and the upstream velocity decrease of the mixed fluid in the mixed phase zone.Pressure-equalizing exhaust from inclined holes leads to a weaker interaction between water and air,so the exhaust velocity and its axial component as well as the mass flow rate increase obviously.Meanwhile,the formation of the pressure-equalizing film gets faster and its influential area extends significantly.