Flow rate measurement and visualization of buoyancy-driven exchange flow by laser doppler velocimeter

An experimental investigation was carried out for the buoyancy-driven exchange flow in a narrow vertical pipe concerning with air ingress process during a stand pipe rupture in high temperature gas-cooled reactor. In the present study, the evaluation method of exchange flow was developed by measuring the velocity distribution in the pipe using laser Doppler velocimeter (LDV) and the flow pattern was visualized by smoke tracer method. It was found that the exchange flow fluctuated irregularly with time and space in the pipe. The velocities of the plumes obtained from visualization were almost the same as the maximum ones measured by LDV. (author)