Laser Doppler Velocimeter Studies of the Pipeflow Produced by a Generic Header

摘要

The report presents recent results obtained in a consortium-sponsored researchprogram on flowmeter installation effects being conducted at NIST-Gaithersburg, MD. The piping element tested and reported here is generic header which has a specific arrangement of one inlet and two outlets. LDV velocity measurements are reported for the pipeflows produced downstream of the header with and without a conventional 19-tube concentric tube bundle flow conditioner. The results indicate that the secondary flow produced by the generic header is very similar to that produced by the closely-coupled double elbows out-of-plane piping configuration. The axial velocities are slower than the ideal flow near the pipe center and higher near the walls. Transverse velocity distributions show a very strong swirl eddy flow pattern produced by this header. This swirl eddy is relatively stable and organized and its dissipation is slower than that observed for the double elbows out-of-plane. The 19-tube tube bundle is quite effective in reducing the transverse velocities associated with the energetic, swirl flow from this header. Several profile indexes are introduced and presented for the header flow to characterize its swirl, profile peakness and flow displacements. These indexes can also be used to develop criteria for improving flow meter performance in the outlet piping from this header.