Validation of CFD and Thermal Hydraulics Codes by Digital Particle Image Velocimetry

Abstract

Abstract Experimental validation of thermal hydraulics and CFD codes of scaled down models and full models of Nuclear Reactor components is very important for reactor system designers and reactor safety experts for optimal design and providing best safety features of the reactor systems. Over the period of time several techniques have been developed for this purpose. Among them Digital Part icle Image Velocimetry (DPIV), a laser based optical technique, is the recent, innovative, promising and flexible enough one so that it can be adapted to a large variety flows. By this technique test time is reduced significantly. DPIV is a non-intrusive optical measurement technique, which allows capturing several thousand velocity vectors within large flow fields instantaneously. DPIV technique is being used in very wide and different applications, from micro flows over combustion to supersonic flows for both industrial needs and research. 2-D DPIV facility having non-intrusive, instantaneous flow visualization with high spatial and temporal resolution features has been developed. It is used for measurement of flow velocity vectors at many (e.g. thousands) points in a flow field simultaneously and it provides instantaneous vector fields and displays velocity vectors in rea l-t ime. DPIV combines flow visualization with accurate quantitative velocity data. 2-D Velocity vectors are obtained by analysis of displacement of tracer particles on images in a known time. The development of visualizat ion tools are powerful enough to at tack the complexity of a resulting flow field but also flexible enough so that they can be adapted to a large variety of different flow. DPIV system has Laser light source, Laser beam delivery system, High speed camera interface, DPIV image acquisition & analysis software, CCD camera, computer controlled synchronizer, seeding particles & PC. This system will enhance our capability of thermal hydraulics, neutronics and mult iphysics modelling by experimental support & actual measurement of parameters, in addition to codes we had with us. Application of DPIV is must for the flow in the separation and reattachment regions where it is directly related to drag and heat transfer coefficients and for Vortex shedding. This facility is being used for basic research of code verification, code development, design optimizations and safety analysis.