Experimental Observation of Non-Ideal Nozzle Flow of Siloxane Vapor MDM
Experimental Observation of Non-Ideal Nozzle Flow of Siloxane Vapor MDM
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硅氧烷蒸气MDM非理想喷嘴流量的实验观察
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
V. Dossena
中科院分区：
文献类型：
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作者：
A. Spinelli;A. Guardone;F. Cozzi;M. Carmine;R. Cheli;M. Zocca;P. Gaetani;V. Dossena
报道了米兰理工大学有机蒸汽试验台（TROVA）的首次实验结果。该设施实现了有机朗肯循环（ORC），其中膨胀过程发生在直轴会聚-发散喷嘴内，这是ORC涡轮叶片通道最简单的几何形状代表。为了降低电厂所需的输入热功率，选择了间歇式运行模式。在允许空气的情况下进行实验，以验证节流阀的操作和测量技术，包括沉降室的总压力和温度测量，沿喷嘴轴的静压测量。采用双通道纹影技术对喷管喉部和发散段的流场进行可视化，并确定了激波在流场中的位置。本文首次对硅氧烷流体MDM （C8H24O2Si3，八甲基三硅氧烷）在相对较低的操作压力下，在靠近液-气饱和曲线的位置进行了非理想喷嘴流动膨胀的实验观察。在喷嘴的发散段内实现了超声速流动，正如在喉段观察到的斜激波所证明的那样，在喉段有一个0.1 mm的凹阶。纹影的可视化受到沿喷嘴镜面一侧发生的凝结的限制。压力测量与观察到的流场是一致的。
The first experimental results from the Test-Rig for Organic Vapors (TROVA) at Politecnico di Milano are reported. The facility implements an Organic Rankine Cycle (ORC) where the expansion process takes place within a straight axis convergent-divergent nozzle, which is the simplest geometry representative of an ORC turbine blade passage. In order to reduce the required input thermal power, a batch operating mode was selected for the plant. Experimental runs with air allowed to verify the throttling valve operation and the measurement techniques, which include total pressure and temperature measurements in the settling chamber, static pressure measurements along the nozzle axis. A double-passage Schlieren technique is used to visualize the flow field in the nozzle throat and divergent section and to determine the position of shock waves within the flow field. The first experimental observation of non-ideal nozzle flows are presented for the expansion of siloxane fluid MDM (C8H24O2Si3, octamethyltrisiloxane) for vapor expansion in the close proximity of the liquid-vapor saturation curve, at relatively low pressure of operation. A supersonic flow is attained within the divergent section of the nozzle, as demonstrated by the observation of an oblique shock wave at the throat section, where a 0.1 mm recessed step is located. Schlieren visualizations are limited by the occurrence of condensation along the mirror side of the nozzle. Pressure measurements are compatible with the observed flow field.