If sharp corners or ribs exist in a pipe, flow separation occurs at the corners and a vena contracta is formed. The fluid must accelerate locally to pass through the reduced flow area at the vena contracta, whose minimum area results when the converging streamlines begin to expand to fill the downstream region. This phenomenon is observed in a typical orifice meter, which has been popularly used to measure the instantaneous flow rate in pipes. The other two most common devices for flow-rate measurement are the nozzle meter and the venturi meter. In many practical engineering applications, the working fluid in rotating machinery flows in sudden expansion or contraction passages or in passage with an orifice. The present study is focused on the secondary flow and heat-transfer performance in an axially rotating pipe with concentric orifices.
展开▼
