Journal of computational fluids engineering (한국전산유체공학회지)

Korean Society of Computational Fluids Engineering (한국전산유체공학회)
권호 표지

LAMINAR FLOW IN THE ENTRANCE REGION OF HELICAL TUBES FOR UNIFORM INLET VELOCITY CONDITIONS

균일입구유속 조건의 나선관 입구영역의 층류 유동

  • Published : 2008.03.31
Download PDF
⟨ Previous Next ⟩

Abstract

A numerical study for laminar flow in the entrance region of helical tubes for uniform inlet velocity conditions is carried out by means of the finite volume method to investigate the effects of Reynolds number, pitch and curvature ratio on the flow development. This results cover a curvature ratio range of 1/10$\sim$1/320, a pitch range of 0.0$\sim$3.2, and a Reynolds number range of 125$\sim$2000. It has been found that the curvature ratio does significantly effect on the angle of flow development, but the pitch and Reynolds number do not. The characteristic angle $\phi_c(=\phi/\sqrt{\delta})$, or the non-dimensional length $\overline{l}(=l\sqrt{\delta}cos(atan\lambda)/d)$ can be used to represent the flow development for uniform inlet velocity conditions. In uniform inlet velocity conditions, the growth of boundary layer delays the flow development attributed to centrifugal force, and in which conditions the amplitude of flow oscillations is smaller than that in parabolic inlet velocity conditions. If the pitch increases or if the curvature ratio or Reynolds number decreases, the minimum friction factor and the fully developed average friction factor normalized with the friction factor of a straight tube and the flow oscillations decrease.

Keywords

References

  1. 1983, Berger, S.A. et al., "Flow in curved pipes," Ann. Rev. Fluids Mech., Vol.15, pp.461-512 https://doi.org/10.1146/annurev.fl.15.010183.002333
  2. 1987, Ito, H., "Flow in curved pipes," JSME Int. J., Vol.30, pp.543-552 https://doi.org/10.1299/jsme1987.30.543
  3. 1975, Yao, L.S. and Berger, S.A., "Entry flow in a curved pipe," J. Fluid Mech., Vol.67, pp.177-196 https://doi.org/10.1017/S0022112075000237
  4. 1971, Dravid, A.N. et al., "Effect of secondary fluid motion on laminar flow heat transfer in helically coiled tubes," AIChE. J., Vol.17, pp.1114-1122 https://doi.org/10.1002/aic.690170517
  5. 1974, Austin, L.R. and Seader, J.D., "Entry region for steady viscous flow in coiled circular pipes," AIChE. J., Vol.20, pp.820-822 https://doi.org/10.1002/aic.690200427
  6. 1974, Patankar, S.V. et al., "Prediction of laminar flow and heat transfer in helically coiled pipes," J. Fluid Mech., Vol.62, pp.539-551 https://doi.org/10.1017/S0022112074000796
  7. 1994, Liu, S. and Masliyah, J.H., "Developing Convective Heat Transfer in Helical Pipes with Finite Pitch," Int. J. Heat Fluid Flow, Vol.15, pp.66-74 https://doi.org/10.1016/0142-727X(94)90032-9
  8. 1997, Lin, C.X. et al., "Laminar forced convection in the entrance region of helical pipes," Int. J. Heat Mass Trans. Vol.40, pp.3293-3304 https://doi.org/10.1016/S0017-9310(96)00381-X
  9. 1979, Mishra, P. and Gupta, S.N., "Momentum Transfer in Curved Pipes: 1. Newtonian Fluids," Ind. Eng. Chem. Process Des. Dev., Vol.18, pp.130-137 https://doi.org/10.1021/i260069a017
  10. 2006, "Fluent 6.3 user's guide," Fluent Inc
  11. 1929, White, C.M., "Streamline flow through curved pipes," Proc. R. Soc. London. Series A, Vol.123, pp.645-663