Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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Gas-liquid flow around an obstacle in a vertical pipe
Prasser, H.-M.; Beyer, M.; Al Issa, S.; Carl, H.; Pietruske, H.; Schütz, P.
This paper presents a novel technique to study the two-phase flow field around an asymmetric diaphragm in a vertical pipe with a nominal diameter of DN200. Main feature of the experiments is a translocation of the diaphragm to scan the 3D void field with a stationary wire-mesh sensor that supplies data with a spatial resolution of 3 mm over the cross-section and a frequency of 2.5 kHz in axial direction. Besides the measurement of time-averaged void fraction fields, novel data evaluation methods were developed to extract estimated liquid velocity profiles as well as lateral components of bubble velocities from the wire-mesh sensor data. The combination of void fraction fields and velocity profiles offer the possibility to analyse the complex flow around an obstacle in order to learn more about similar flow situations in components of power and chemical plant equipment. Selected plots reveal the behaviour of the flow, e.g. at sharp edges and within recirculation areas.
This paper based on air-water and steam-water (6.5 MPa) test runs which were performed with liquid superficial velocities (JW) between 0.1 and 1.6 m/s. The JG was changed in the range of 0.04 to 0.84 m/s.
A detailed uncertainty analyse of the velocity assessments finishes the presented paper. Among others, it includes remarks about a comparison with a second method for calculating radial gas velocity profiles the cross-correlation.
Keywords: Two-phase flow; flow around an obstacle; gas fraction distribution; axial and lateral velocity fields; wire-mesh sensors
- Nuclear Engineering and Design 238 (7)(2008), 1802-1819