RT Journal Article ID 51f36fa62b5f3ea9 A1 Manglik, Raj M. A1 Maramraju, S. A1 Bergles, Arthur E. T1 The Scaling and Correlation of Low Reynolds Number Swirl Flows and Friction Factors in Circular Tubes with Twisted-Tape Inserts JF Journal of Enhanced Heat Transfer JO JEH(T) YR 2001 FD 2001-12-01 VO 8 IS 6 SP 383 OP 395 AB This paper assesses the scaling and correlation of fully developed swirl generated by twisted-tape inserts in laminar circular-tube flows. The tape-induced secondary fluid circulation is shown to be characterized by a helical vortex, which grows and breaks up into a pair of counterrotating vortices with decreasing tape-twist ratio y and/or increasing axial flow Reynolds number Re. The validity of correlating isothermal friction factors in such fully developed, two-vortex-cell laminar flows by the swirl parameter (Sw = Res / √y) proposed in an earlier study (Manglik and Bergles [1993a]) is evaluated. Experimental data and computational simulations reported in the literature for a wide range of laminar flow conditions (43 < Re < 2720) and twist ratios (1.5 ≤ y) of the tape inserts are considered. All data and numerical results are found to be in excellent agreement (within ±10%) with the predictions of the Manglik and Bergles f-correlation. This clearly establishes its generalized design applicability as well as verifies the scaling of tape-induced swirl flows by the parameter Sw. PB Begell House LK https://www.dl.begellhouse.com/journals/4c8f5faa331b09ea,247e464779c7bb40,51f36fa62b5f3ea9.html