Flow and liquid turbulence structure in developing two phase flow systems

点击翻译按钮获取中文摘要

Gas-liquid two-phase flows are important in a number of engineering applications. For example, the safety analysis codes for the nuclear energy industry require closure relations for the vapor-liquid interfacial transfer terms, while accurate two phase pressure drop models are necessary to design the piping systems in the oil and gas industry. In these and other applications, the two phase flow can occur in complex piping geometries such as sudden area changes, orifices, bends and valves under a variety of flow conditions. Thus, it is important to understand the effect of different piping components on the two phase flow, especially in the developing regions downstream of these components, to develop reliable mechanistic models. The overall objective of this proposal is to investigate the flow and liquid turbulence structure of developing two-phase flows. In particular, the developing flow downstream of piping components and in the entrance regions will be investigated. The flow and turbulence structure of the two phase flows will be investigated using an existing 1.5-inch diameter horizontal air-water flow loop and a 8-inch vertical air-water flow loop. The local void distribution will be measured using capacitance and optical probes, while the liquid velocity and turbulence will be measured using hot film anemometry. A four-point optical probe will be used to determine the change in the bubble shape and size due to bubble coalescence/break-up. A high speed Particle Image Velocimetry (PIV) system will be adapted to measure the liquid turbulence field around the bubbles. There are few studies, especially of the flow and turbulence structure in the developing region of two-phase flows. However, this region is important in many multiphase systems and plays a determining role in many engineering applications. The measurements that will be performed here will be unique and provide physical insight into this complex phenomena and provide input to develop mechanistic models that can be incorporated into different engineering applications.