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The Effect of the Variation of the Downstream Region Distance and Butterfly Valve Angle on Flow Characteristics in a 90 Degree Bended ElbowDOI: 10.4236/mme.2014.43013, PP. 133-143 Keywords: Flow Disturbance, Shear Stress, 90 Degree Bended Elbow, Butterfly Valve, FAC Abstract:
This study presents the
numerical evaluation about the impact of flow disturbance near the intrados and
extrados regions of the 90 degree bended elbow using CFX for several practical
cases where the 90 degree bended upward elbow is located in a proximity to the
butterfly valve and the butterfly valve open angle is changed. For the change
of a butterfly valve open angle from 60% to 100% and the increase of the
distance between a valve and a 90 degree bended elbow, the effect of FAC
(Flow-Accelerated Corrosion) in the 90 degree bended elbow may be neglected
because the value and distribution of the velocity and shear stress is rapidly
decreased comparing with the present status installed in an industry, and the data
of 100% valve open (Case 3) and L/D ≈ 5 (Case 4) are very good agreement
comparing with the reference data, L/D ≈ 8 (Case 2). The reasons are that flow already
maintains a fully developed condition and a steady state in spite of less
distance than the reference case, L/D = 8. Therefore, smooth flow fields have
approached at a 90 degree bended elbow. Then, the effect of shear stress and
vortex is hardly investigated around the intrados area of 90 degree bended
elbow.
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