Preferred URLC mode boundaries in space from Kubitschek and Weidman (Ref. 1), where and . (Copyright 2007 Cambridge University Press—reprinted with permission.)
Schematic of viscous RLJ experimental test facility.
Line along which parameter space is traversed by varying rotation rate with fixed jet radius and fixed fluid properties for SAE30 oil at , where , , and . Note and and the points along the traverse line represent 52.3-rad/s increments.
(Color online) Still images of helical instabilities for SAE30 oil at approximately : (a) at , (b) at , (c) at , and (d) weak at .
(Color online) Typical growth rate measurement imaging of (a) base flow at zero rad/s (15-s exposure), (b) instability at (15-s exposure), and (c) instability at (still).
(Color online) Typical growth rate measurement image processing results showing (a) left and right peak amplitudes and (b) disturbance peak amplitudes in linear-log coordinates.
Time series images of the instability acquired using high-speed video showing progression of a single wave crest around the liquid jet at a rotation rate of : (a) , (b) , (c) , (d) , and (e) .
Comparison of theoretically predicted URLC and experimentally measured RLJ (a) growth rates vs in log-linear coordinates and (b) growth rates vs . The dashed vertical lines represent predicted URLC mode transitions.
Comparison of theoretically predicted URLC and experimentally measured RLJ (a) frequencies vs in log-linear coordinates and (b) frequencies vs . The open symbols indicate observations of subordinate intruding fins.
(Color online) Series of images showing the transition with increasing rotation rate. (a) at , (b) very weak at , (c) weak at , (d) stronger at , and (e) full at .
(Color online) Observed viscous RLJ (a) undisturbed contracted length vs rotating tube exit swirl parameter marking the onset of instability and (b) still image showing instability immediately downstream of the rotating tube exit for .
(Color online) Still image of the viscous RLJ at showing the evolution of the helical instability toward ultimate breakup.
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