Design and operation of a two-phase flow research facility

In this report we describe the new two-phase flow facility that has been constructed at Brown University. Included is the design philosophy that led us to select a blow-down, Freon tunnel as the means of studying the flow of a pure substance undergoing liquid-vapor phase changes. Each component is discussed from the initial design considerations, through sizing calculations, to actual system specifications. Special emphasis is placed on the instrumentation and automatic data acquisition and processing system. Finally a sampling of results obtained so far is presented. Section 1 gives the reasons for the construction of the facility and lists some of the uses and objectives of its operation. The reader can gain a good overview of the facility from Section 2 without a great deal of detail. In Section 3 we present the rationale for the particular design choices that were made and give details about the selection and sizing of all major components except the instrumentation. The latter subject is treated in Section 4 where we discuss the temperature and pressure probes, mass flow rate measurement, and other instrumentation. Section 5 is devoted to the test section proper where all the two-phase flow measurements and observations take place. The electronic data acquisition and facility control system is the subject of Section 6. Results on two-phase friction factors and flow pattern observations in a horizontal pipe are given in Section 7 along with the ranges of flow that have been covered so far. In capsule summary, the two-phase flow test facility is operational and has demonstrated a wide range of flow conditions from purely liquid to purely vapor through a variety of two-phase situations. Only horizontal flows have been studied so far, but the test section has been designed to operate in inclined positions up to fully vertical. The instrumentation performs very well as does the fully automatic control system. We believe the test facility is capable of yielding highly reliable and accurate data on two-phase flows which will be of great value in practice and in validating the various theories that have been put forth to describe this phenomenon