Exploring Capabilities of Electrical Capacitance Tomography Sensor and Velocity Analysis of Two-Phase R-134A Flow Through a Sudden Expansion
Technical Report,01 Jan 2015,30 Apr 2017
University of Dayton Research Institute Dayton United States
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Future high-performance aircraft will require advances in the understanding of two-phase heat transfer in order to manage the ever-increasing airframe and engine heat loads. Two-phase liquid-vapor refrigerant systems are one solution for the heat removal from these systems. However, they require more study before implementation. This study examines the velocities of two-phase liquid-vapor flows with the use of high speed visualization. In flow channels where high speed visualization cannot be used, there are other noninvasive techniques for analyzing flow the flow, such as electrical capacitance tomography ECT. In this thesis, capabilities of ECT sensors such as the location in the sensor where there is a detected change in permittivity as well as the sensors ability of determining simple surfaces are explored to assist in future work. Four sensors were tested and static experiments were able to determine location along the length of the sensor where a change in permittivity was detected. Each sensor tested showed a detection of permittivity at a different location than expected when comparing with the physical location of the electrodes according to the dimensional drawings of the sensors. Experiments testing the sensors ability to detect a surface showed that with a well-defined surface there was a noticeable change when the surface was rotated to different orientations. In fluid flow tests, high speed video analysis showed the velocities of 71 tracked points at varying level of qualities. These velocities were analyzed and the data from these experiments were compared with pressure drop correlations.