具冷卻流儲存槽之渦輪葉片薄膜冷卻數值模擬研究

Numerical Investigation on Film Cooling of a Turbine Blade with Coolant Plenum

戴昌賢(Chang-Hsien Tai) ； 高阿福(A. Fu Kao) ； 苗志銘(Jr-Ming Miao) ； 郭家彣(Jia-Wen Kuo)

《中國航空太空學會學刊》 34卷4期 (2002/12) Pp. 353-361

https://doi.org/10.6124/TAASRC.200212_34(4).08

摘要

在旋轉機械研究方面，渦輪轉子葉片公認具有相當複雜的熱流場特性，尤其是安置冷卻噴流孔後之薄膜冷卻葉片，而完整地研究範疇應該包含內部冷卻通道與外部冷卻效應。葉片整體流場特性與其渦輪效益有相當大的關係，本文主要透過計算流體力學方法對具冷卻流噴孔與儲存槽的渦輪轉子流場進行熱流場模擬。爲能呈現出真實之流場現象，模擬範圍除相鄰葉片所構成之通道流場外，並包含冷卻流儲存槽與冷卻流通道。所採用數值模擬程式(HASP)是作者等所發展的一求解三維且雷諾均值(Reynolds-averaged)Navier-Stokes方程式，並基於有限體積法對統御方程式進行離散。爲能獲得較精確之流場性質，並採用多步階、上風通量差分等數值法則。由模擬結果可明顯發現藉由蓮蓬頭式薄膜冷卻設計，可有效降低葉片前緣停滯區附近之溫度；經由不同位置之冷卻孔流場分析後，發現冷卻流噴出孔排因所處位置之壓力梯度不同，噴射孔附近之流場表徵以及葉片表面之薄膜冷卻效率分佈也會不同。另一方面，過去研究一般將噴孔面速度分佈以平均或拋物線曲線的邊界條件加以設定的簡化作法，與實際情況並不吻合，所以本研究在數值模擬上將冷卻流儲存槽與冷卻流通道納入計算域，雖然增加實體模型之計算網格系統與程式收斂之困難度，但是與真實情況更爲接近。

關鍵字

計算流體力學 ； 轉子葉片 ； 蓮蓬頭式薄膜冷卻 ； 冷卻流儲存槽

並列摘要

The performance of a gas turbine is deeply influenced by the flow characteristic around the blade, especially for film-cooled blade. Typical blade is protected by introduction of internal cooling and external film cooling. A three-dimensional Navier-Stokes analyzer, HASP, based on control volume method is developed to simulate the complex flow field on a rotor blade with film cooling holes, coolant plenum, and the passage between adjacent blades. The governing Navier-Stokes equations are solved by an improved numerical method that uses an upwind flux-difference split scheme for spatial descretization and an explicit optimal smoothing multi-stage scheme for time integration. Present results indicate that the blowing of the coolant flow in the leading edge of the blade will obvious reduce the surface temperature as compared to those without cooling. A higher distribution of adiabatic film cooling effectiveness value can be observed on the suction side of blade, especially near by the holes. In addition, the holes in different position of blade have distinguish features in developing of coolant flow structure due to various freestream boundary-layer pressure gradients around the leading edge. Neither uniform nor parabolic distribution of velocity in the exit plane of coolant hole is observed in present study. For more practice, a complete simulation model should include the coolant plenum and rows of injection hole. Present study also tests the influence of mainstream inlet angle on the passage flow structure and temperature distributions over blade's surfaces.

並列關鍵字

CFD ； Rotor blade ； Shower-head film cooling ； Coolant plenum