气液两相状态下有衬里水带水动力特性研究

Research on Hydro-dynamic Characteristics of Lined Fire Hoses with Gas-liquid Two-phase Flow

消防水带内工质为有压气液两相流状态时,其工作过程中会产生无规律振动,极易造成水带磨损和水枪的难以掌控,影响灭火救援工作的开展。对气液两相状态下消防水带水动力特性展开研究,通过数值模拟和实验的方法探索水带内气泡流动、合并、破碎、脱离的过程,分析气相比例、运行压力对水带稳定性的影响。数值计算中考虑重力、表面张力和壁面黏附作用。研究结果表明:气相比例是导致水带不稳定运行的重要因素,但存在一个极大值;运行压力的增加会直接导致水带运行不稳定性的增大,但两者之间未发现定量关系;气液两相的剧烈扰动,是造成气泡的流动、合并、破碎的主要诱因,在气液两相流状态下,应尽量避免水带高压运行。

Irregular vibration may occur when fire hoses are transferring pressurized gas-liquid two-phase flow, which is likely to wear the hoses, which makes it harder to control the water gun, and thus influences the efficiency of fire extinguishment and rescue. A deep research on the hydro-dynamic characteristics of fire hoses with gas-liq- uid two-phase flow was made by exploring the process of streaming, merging, breakage, and departure of bubbles inside the hoses. The gas-liquid ratio, and the impact of operating pressure on the hose steadiness were analyzed through numerical simulation and experiments. The gravity, surface tension and wall adhesion were considered in the calculation. It can be seen from the results that gas-liquid ratio is an important factor for the unsteadiness of operating hoses, but an extreme value is expected. The increase of operating pressure is a major cause for the bubble breakage, and therefore hoses should not be operated under a high pressure as far as possible when transferring gas- liquid two-phase flow.