Measurements of void fraction, liquid temperature and velocity under boiling two-phase flows using thermal-anemometry

Forced convective boiling is of great interest for several applications in the power and process industry, particularly nuclear plants. Under certain nominal, incidental or accidental conditions, crisis (considering Departure from Nucleate Boiling as well Dry-Out) may lead to mechanical damage heated surface. An accurate prediction conditions leading occurrence this phenomenon then essential. It believed that such an objective cannot be reached unless a good description associated two-phase flow provided. In our work, we propose use thermal anemometry measuring void fraction, liquid temperature velocity high pressure Freon R134A flow. Experiments have been conducted circular tube whose inner diameter length are 19.2 mm 3.5 m, respectively. The by Joule effect. sensor (hot-wire d5μm) has operated with Constant Current mode (CCA) multiple overheating method, which classical gas measurements but seems very innovative flows. This used access simultaneously temperature. To consider effect on calibration, new non-dimensional representation calibration curve proposed. frequency response probe also improved using digital compensation method. method first checked single-phase flows shown it was possible get both mean fluctuating profiles. For flows, specific two-steps approach developed measure fraction where necessary set overheat ratio wire surface secondly case not acceptable due probability density functions adapted pioneering work Delhaye (1969). Some tests experimental results compared previous ones thermocouples optical probes respectively fraction. uncertainties carefully analyzed they estimated close 0.5 °C temperature, ±2% (absolute uncertainty) ± 5% (relative velocity). Those data aim NEPTUNE_CFD code validation.