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Very few investigations of bubbly two-phase flows have used X-hot-film probes for the measurement of the turbulence field in the continuous phase. Therefore the interactions between the sensors of the X probe and the bubbles are not well known and thus can lead to errors in the determination of turbulence parameters. To gain understanding of the interaction, investigations of static and dynamic bubble-sensor interactions were carried out. In the static investigations a probe that is moved through stagnant water interacts with a bubble that is fixed to a small nozzle. These experiments help us to understand signals for situations in which the liquid and the bubble move with the same speed. In this case, the so-called post-signal occurring at the exit of the sensor penetration through the bubble is caused by the deformation of the bubble surface by the sensor and its prongs rather than by the flow field. In the dynamic investigations the probe is fixed in a vertical flow and it interacts with single bubbles of a bubble stream, as is the case in any two-phase flow situation. A bubble-probe interaction map is proposed that classifies the behaviour into four different modes of interaction. In both series of measurements, various parameters characterizing bubble signals were determined. A synchronized video system is used for visual investigations of deformations of the bubble surface. The results will be used for the future development of a so-called bubble elimination algorithm that is used for filtering the bubble signals out of the two-phase signal.

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