GLOBAL RAINBOW THERMOMETRY APPLIED TO A FLASHING TWO- PHASE R134-A JET

Two-phase flows hold an interest in many areas of science and engineering. In the safety field, one such topic is the accidental release of flammable and toxic pressure-liquefied gases. In case of such a release, a flashing vapor explosion takes place resulting in a very dense two-phase cloud. In particular, if the released substance is flammable, this cloud can be combustible and can lead to deflagration or detonation. For understanding the source processes of flashing and risk assessment, data related to cloud characteristics (i.e. droplet size, velocity, temperature) is needed especially in the near region of the release. Due to the non-equilibrium nature of the near field regions accurate data measurement is not possible with intrusive techniques. Therefore, laser-based optical techniques like Global rainbow Thermometry (GRT) and Phase Doppler Anemometry (PDA) are tempted. The main object of the present work is to assess the mean size and temperature evolution along a flashing two phase R134A jet. GRT gives a smaller mean diameter than PDA because GRT measures only the most spherical thus smaller droplets. The temperature evolution by GRT differs much from thermocouple measurements