DOI QR코드

DOI QR Code

Numerical Study of the Rib Arrangements for Enhancing Heat Transfer in a Two-pass Channel of Large Aspect Ratio

종횡비가 큰 이차유로에서 냉각성능 향상을 위한 요철배열 연구

  • 한솔 (연세대학교 기계공학부) ;
  • 최석민 (연세대학교 기계공학부) ;
  • 손호성 (연세대학교 기계공학부) ;
  • 조형희 (연세대학교 기계공학부)
  • Received : 2016.05.11
  • Accepted : 2016.11.30
  • Published : 2017.03.01

Abstract

The present study investigated the effect of the rib arrangement and a guide vane for enhancing internal cooling of the blade. Two types of rib arrangements were used in the first and second passage in parallel. Aspect ratio of the channel was 5 and a fixed Reynolds number based on hydraulic diameter was 10,000. The attack angle of rib was $60^{\circ}$, rib pitch-to-height ratio (p/e) was 10, and the rib height-to-hydraulic-diameter ratio ($e/D_h$) was 0.075. The effect of an interaction between Dean vortices and the secondary vortices from the first passage was observed. Overall, the attack angle of rib in the first passage was dominant factor to heat transfer and flow patterns in turning region. Also, the channel with a guide vane showed enhanced heat transfer at the tip surface with reducing flow separation and recirculation.

터빈 블레이드의 내부냉각 설계 강화를 위해 설치된 경사요철과 가이드 베인에 대한 연구를 진행하였다. 채널의 입구로 들어오는 공기와 요철이 만나는 각도를 기준으로, 서로 상반된 두 가지 요철배열을 전연면과 후연면에 평행하게 배치하였다. 채널의 종횡비(AR)는 5:1이고, 요철의 각도는 $60^{\circ}$, 요철의 높이와 요철간 간격 비($e/D_h$)는 0.075이다. 레이놀즈 수는 10,000으로 고정하였다. 요철배열에 따른 2차 유동과 딘 와류의 상호작용이 곡관부와 전체 채널의 열전달 결과와 유동특성에 어떠한 영향을 미치는지 확인할 수 있었다. 결론적으로 첫 번째 유로의 요철배열이 팁 면의 열전달 분포에 지배적인 요인이며, 곡관부에서 유동의 분포에도 영향을 미쳤다. 또한 U자 형상 가이드 베인을 사용하였을 때 모든 요철에서 팁 면의 열전달 값이 상승하였으며, 특히 공기와 요철의 충돌각도가 양의각도일 때 가장 높은 냉각성능계수를 보였다.

Keywords

References

  1. Metzger, D.E. and Sahm, M.K., 1986, "Heat Transfer Around Sharp 180 Degree Turns in Smooth Rectangular Channels," Journal of Heat Transfer, Vol. 108, pp. 500-506. https://doi.org/10.1115/1.3246961
  2. Murata, A. and Mochizuki, S., 2004, "Large Eddy Simulation of Turbulent Heat Transfer in a Rotating Two-pass Smooth Square Channel with Sharp $180^{\circ}$ Turns," International Journal of Heat and Mass Transfer, Vol. 47, pp. 683-698. https://doi.org/10.1016/j.ijheatmasstransfer.2003.07.022
  3. Kim, K.M, Lim, Y. Y., Lee, D. H., Rhee, D. H. and Cho, H. H., 2006, "Local Heat/mass Transfer Phenomena in Rotating Passage, Part 1: Smooth Passage," Journal of Thermophysics and Heat Transfer, Vol. 20, pp. 188-198. https://doi.org/10.2514/1.14907
  4. Han, J.C. and Park, J.S., 1988, "Developing Heat Transfer in Rectangular Channels with Rib Turbulators," International Journal of Heat and Mass Transfer, Vol. 31 pp. 183-195. https://doi.org/10.1016/0017-9310(88)90235-9
  5. Bonhoff, B., Parneix, S., Leusch, J., Johnson, B. V., Schabacker, J. and Bolcs, A., 1999, "Experimental and Numerical Study of Developed Flow and Heat Transfer in Coolant Channels with 45 Degree Ribs," International. Journal of Heat and Fluid Flow, Vol. 20, pp. 311-319. https://doi.org/10.1016/S0142-727X(99)00011-9
  6. Han, J.C., Zhang, Y. M. and Lee, C. P., 1991, "Augmented Heat Transfer in Square Channels with Parallel, Crossed, and V-shaped Angled Ribs," Journal of Heat Transfer, Vol. 113, pp. 590-596. https://doi.org/10.1115/1.2910606
  7. Bunker, R.S., 2001, "A Review of Turbine Blade Tip Heat Transfer," Annals of the New York, Academy of Sciences, Vol. 934, pp. 64-79.
  8. Sunden, B. and Xie, G., 2010, "Gas Turbine Blade Tip Heat Transfer and Cooling: A Literature Survey," Heat Transfer Engineering, Vol. 31, pp. 527-554. https://doi.org/10.1080/01457630903425320
  9. Xie, G., Sunden, B. and Zhang, W., 2011, "Comparisons of Pins/Dimples/Protrusions Cooling Concepts for a Turbine Blade Tip-wall at High Reynolds Numbers," Journal of Heat Transfer, Vol. 133.
  10. Chung, H.Y., Park, J. S., Park, S. J., Choi, S. M., Rhee, D. H. and Cho, H. H., 2015, "Augmented Heat Transfer with Intersecting Rib in Rectangular Channels Having Different Aspect Ratios," International Journal of Heat and Mass Transfer, Vol. 88, pp. 357-367. https://doi.org/10.1016/j.ijheatmasstransfer.2015.04.033
  11. ANSYS Inc., 2013, ANSYS Reference Guide (Release 15.0), http://www.ansys.com.