게 유선들이 간극에서 회전후 말단을 벗어나 흡입면쪽에서 다시 누설와 류의 일부가 된다.
(4) 말단간극을 포함하지 않은 경우, 예측된 슈라우드에서의 열전달 특성은 선단부분에서 높게 나타나며, 이는 측정된 결과와 같다. 그러나 후류 영 역에서 예측된 결과는 측정된 결과와 비교하여 낮게 나타났으며, 통로 와류에 의해 열전달 계수가 높은 영역은 예측하지 못하는 것으로 나타 났다.
(5) 말단간극을 포함한 경우, 슈라우드의 선단과 압력면 영역에서 열전달 계수 분포는 예측과 측정된 결과가 같은 경향을 나타내었다. 그러나 누 설 유동으로 일어나는 누설와류와 블레이드 말단내의 와류 영역의 열전 달 특성은 예측된 결과에서 반영되지 못하였다.
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Abstract
Numerical Study of Flow through Turbine Cascades and Heat Transfer on the Shroud with/without Tip Clearance
by Seung-yong Yang
The Graduate School of Automotive Engineering, Kookmin University, Seoul, Korea
In the turbine blades, severe heat load occurs between the blade tip and shroud region due to hot combustion gas through tip clearance.
Thus, for the improvement of the cooling schemes and the durability of the blade, it is important to understand flow and heat transfer characteristics at the blade tip and shroud.
In this study, flow through linear cascades of turbine blade and heat transfer on the shroud with/without tip clearance were analyzed through a numerical method. RNG and low-Reynolds-number k - ε model is employed for flow field and heat transfer analysis, respectively.
Two attachment lines, two separation lines and saddle point were identified from velocity vector and stream line plots. The development and generation of the horseshoe vortex, passage vortex, leakage vortex, vortex within tip clearance and other vortex were clearly simulated.
Predicted heat transfer coefficient distributions, at stagnation region of the leading edge in the case without tip clearance and pressure side region in the case with tip clearance were consistent with the general tendency. However, some region, especially at growth region of vortex, result in some uncertainty.
부록 A. Blade Data (x,y)
Table A.1 Turbine blade geometry
Pressur e Side Suction Side
0, 0