不凝结气体对蒸汽浸没射流压力振荡的影响

  目的  船用蒸汽动力系统进行蒸汽排放时，蒸汽射流冷凝是一个常见的物理过程。为了充分掌握此类开放空间纯蒸汽浸没射流的基础物理现象，采用Mixture两相流模型开展CFD仿真研究。  方法  基于实验结果对传热关系式进行修正，以汽相体积份额为0.95作为度量汽羽长度的临界分数，对比分析不同凝水温度和进口压力条件下浸没射流冷凝汽羽的空间分布、速度场、温度场及压力场分布特性。  结果  仿真结果表明：不同的进口条件将影响浸没射流冷凝汽羽的形态；在稳定的浸没射流冷凝过程中，汽羽核心区呈现出相对低温的状态，汽羽轴向的压力分布呈现出波动状态；验证了汽羽内部膨胀-压缩波的存在性，且随着蒸汽进口压力的增加，膨胀-压缩波的波动振幅和空间范围也随之增加。  结论  研究成果可为蒸汽射流冷凝的优化设计提供参考。

Effect of non-condensable gas on pressure oscillation of submerged steam jet

  Objectives  During the discharging of ship-used steam power, steam jet condensation was a common physical process. In order to fully grasp the fundamental physical phenomena within steam submerged jet and condensation under open space, CFD simulation with Mixture multiphase model was carried out.  Methods  With the experimental results, heat transfer model was modified. Vapor volume fraction 0.95 was regarded as the critical value to measure the length of plume. Spatial distribution of plume, velocity, temperature and pressure fields for steam submerged jet and condensation under different inlet pressure and condensed water temperature conditions were studied.  Results  Simulation results show that different initial state would affect the plume shapes. Within stable steam submerged jet and condensation, a relatively lower temperature area is appeared in the core of plume. Pressure distribution along the axial direction is present in a fluctuating form, verifies the existence of the expand-compress wave inside the plume, amplitude and spatial wavelength of the pressure fluctuation are increased with increasing inlet pressure.  Conclusions  Study in this paper could provide guidance for the optimal design of steam submerged jet and condensation.