Visualization of Submerged Cavitating Jet: Part Two – Influences of Hydrodynamic Conditions, Nozzle Geometry and Visualization System Arrangement

In visualization results of highly-submerged cavitating water jet obtained by a digital camera, the influence of parameters such as: injection pressure, nozzle diameter and geometry, nozzle mounting (for convergent / divergent flow), cavitation number and exit jet velocity, were investigated. In addition, the influence of visualization system position was studied. All the parameters have been found to be of strong influence on the jet appearance and performance

Visualization of Submerged Cavitating Jet: Part One –The Phenomenon,Time-Synchronization, Photo Objectives and Sono-Luminescence

In order to study the jet structure and the behavior of cloud cavitation within time and space, visualization of highly submerged cavitating water jet has been done using 4-Quik-05 camera. This included obligatory synchronization technique and several types of lenses. The influencing parameters, such as: injection pressure, downstream pressure and cavitation number were experimentally proven to be very significant. The recordings of sono-luminescence phenomenon proved the bubble collapse everywhere along the jet trajectory. In addition, the effect of temperature on sono-luminescence was investigated

Measuring of velocity and temperature field in a model of reactor vessel downcomer and cold-legs inlets

In nuclear power plants (NPP) as operating plants become older, the piping system Tees and the downcomer are susceptible to turbulent temperature mixing effects (thermal fatigue) that cannot be adequately monitored by common thermocouple instrumentation. The work has been initiated at MTA EK where the mixing flow process is investigated in order to reduce the temperature fluctuation, thus decrease the thermal fatigue risk and to improve the accuracy and reliability of thermal fatigue load positions in the system. A model of a part of the downcomer has been built containing three main loop pipes (cold-legs) and one ECCS pipe (branch pipe). The whole model is made of plexi-glass so optical measurements can be performed from any positions. Particle image velocimetry (PIV) and Laser induced fluorescence (LIF) measurements in significant crosssections in addition to FLUENT calulations has been made. The obtained results showed the influence of important parameters on the mixing process, the ratio of flow rate between the main pipe and the branch pipe has big infelunce on the mixing process, the existence of eblow configuration enhances the mixing flow process in the system. The comparison between PIV, LIF and FLUENT results shows a good agreements. Both PIV and LIF techniques can be used as good providers for data base and to validate CFD results