水下自激吸气式射流装置流动特性及性能研究

运用欧拉气液两相流模型和RNG k-?湍流模型,对水下自激吸气式射流装置水气两相流动特性进行数值模拟,研究了装置吸气和不吸气条件下内部压力分布、水气两相流速分布以及水气混合过程;开展了装置射流冲击性能试验,分析了装置的冲击力和冲蚀效果的变化规律。研究结果表明:与不吸气相比,装置吸气后内部压力接近大气压;吸气后射流核长度和下喷嘴出口断面流速明显大于不吸气;水气完全混合后,在射流核两侧的漩涡区,气相浓度较高,从射流核到漩涡区气相浓度逐渐增大;装置计算吸气量、典型测点压力与试验结果吻合较好;不同围压和靶距下,装置吸气后靶心及附近位置冲击力明显高于不吸气,说明了装置产生了聚能效应;装置吸气后冲蚀深度和冲蚀体积明显大于不吸气,但冲蚀表面积略有下降。

Flow characteristics and performance of underwater self-excitation inspiration jet device

In this study, we have simulated the water-air flow characteristics of an underwater self-excitation inspiration jet device using an Eulerian two-phase flow model and RNG k-? turbulence model, focusing on the distributions of internal pressure and water-air flow velocity of this device and its water-air mixing process in inspiration and non-inspiration cases. Experimental tests were conducted to examine its performance and the variation trends of its impact power and erosion effect. The results show that relative to the non-inspiration case, inspiration makes the internal pressure closer to atmospheric pressure and brings about longer jet cores and significantly greater velocity at the outlet of the lower nozzle. In the inspiration case, high air concentration occurs in the whirlpool regions outside of the jet core if air is fully mixed with water, and air content increases gradually from the core to whirlpool. And the impact power at the target center and in its vicinity is significantly higher than that of the non-inspiration case, explaining the fact that such a device has a gathering energy effect. Moreover, erosion volume and erosion depth increase dramatically while the area of eroded surface decreases slightly. Calculations of inspiration capacity and pressures at typical locations show good agreement with test results.