Experimental comparison of flow pattern detection techniques for air-water mixture flow

The complicated and complex nature of two-phase mixture flow phenomenon itself requires detection, monitoring and description of flow pattern influence on the dynamic parameters of mixture flow. The experimental research documentation and control of real mixture flow requires detection, monitoring and measurement of many parameters associated with concentration, velocity and pressure with their distributions in time and space. In addition to the complexity of two-phase mixture flow, there is difficulty in comparing results of experiments from different publications due to the limitation in documentation in the used measurement techniques as well as experimental methodologies. Four often-used measurement methods for flow pattern detection were identified, developed and implemented in the constructed vertical experimental system. This computer-aided experimental system (CAES) was used to generate all typical flow patterns in vertical flow and measure all chosen dynamic parameters (concentration, pressure, and interfacial phenomenon) simultaneously. In this CAES the flow pattern detection system is composed of the application of two different electromagnetic methods (capacitive and resistive), pressure fluctuation method and an optical method. In the reported experimental research on vertical adiabatic air-water flow, results were obtained using all four chosen measurement methods simultaneously. The results allowed a direct comparison of the efficiency of each method in terms of individual ability and sensitivity in the detection of flow patterns. The different sensitivity and abilities of individual methods to detect flow patterns were documented and discussed. (C) 1999 Elsevier Science Inc. All rights reserved.