湿空气超音速凝结实验平台设计

Design of an experimental platform for the moist gas supersonic condensation

音速喷嘴作为流量计和量值传递标准,被广泛应用于工业过程中。当介质为蒸汽或含湿气体时,其流过音速喷嘴会由于自身温降而发生凝结现象,这对音速喷嘴计量产生重要影响。为研究音速喷嘴中的凝结现象,设计了一套凝结实验平台,分为气路调节系统、高压雾化系统和蒸发加湿系统3部分。针对核心的蒸发加湿单元设计,建立了有限空间内液滴蒸发模型。基于液滴最大蒸发时间,设计了蒸发器尺寸和结构并通过计算流体动力学（CFD）数值模拟验证了设计效果。通过压力控制、管道加热、液滴雾化和蒸发加湿,可实现压力pa=0.10.6 MPa、温度Ta=45-65℃和相对湿度RH=0%-100%的快速准确调节。实验结果表明,本实验平台可为音速喷嘴提供不同压力、温度和相对湿度的准确入口条件,为凝结现象研究提供实验基础。

The sonic nozzles have been widely used in the industrial process as a flow meter and transfer standard. For the steam or moist gas,when the fluid flows go through sonic nozzles,the condensation phenomenon occurs for its temperature drop and will have an important influence on the measurement accuracy of sonic nozzles. To study the condensation in sonic nozzles, a condensation experimental platform is set up. The platform is divided into gas control system,high-pressure micro-fog generator and evaporative humidification system. For improving the performance of the evaporative humidification unit,the droplet evaporation model within limited gas space is established. Based on the maximum droplet evaporation time,the size and structure of the evaporator are designed and verified by computational fluid dynamics（CFD） numerical simulation. Through pressure control,pipe heating,droplets atomization and evaporative humidification,the platform can adjust system pressure from 0. 1 to 0. 6 MPa,temperature from 45℃ to 65℃ and relative humidity from 0% to 100% quickly and accurately. Experimental results showed that the designed platform can provide accurate inlet conditions with different pressures,temperatures and relative humidities for the research of the condensation phenomenon in sonic nozzles.