| Summary: | 碩士 === 國立臺灣大學 === 機械工程研究所 === 81 === intensity薄膜冷卻是降低氣渦輪引擎葉片熱應力負載最常使用的方法，
故本實驗藉由奈揮發質傳法研究多排蓮蓬頭式薄膜冷卻對渦輪葉片質(熱)
傳的影響。較之於直接熱傳量測法；奈揮發質傳法能獲得更詳盡的實驗資
料，在操作程序上也較為簡便；此外奈揮發質傳法亦能避免熱傳導及熱輻
射的誤差。雖然實驗量測所得為葉片表面對時間取平均值的質傳分佈，但
可利用熱質傳對比法(Heat/Mass Transfer Analogy)，將質傳係數轉換為
熱傳係數。本實驗量測低紊流強度(Tu=0.2 %)，出口雷諾數為Re2=397000
無端牆影響下，兩種不同吹出比(M=0.7，M=0.8)，對葉片表面質傳係數分
佈的影響，並在無噴射流影響區域量測葉片表面壓力恢復係數，將其依相
關理論計算，找出流場結構，以便與奈揮發質傳量測結果相驗證。由量測
結果顯示；有噴射流影響區域在葉片凸面和凹面頭端附近均造成劇烈的三
維週期跨向質傳分佈，且使得下游質傳量大幅提昇；在葉片中間凸面不再
有二次不穩定Lambda渦流出現及使凹面原有的泰勒苟德勒渦流消失。無噴
射流影響區域，凸面邊界層不穩定點在分離點之前產生，但凹面在頭瑞附
近即產生邊界層分離形成一極小的分離氣泡。
Experimental measurements were conducted in an open-type wind
tunnel to study the convective transport phenomena over a
turbine blade under an effect of multi-row showerhead type film
cooling.A naphthalene sublimation technique was used to obtain
the mass transfer distribution over the test blade. By applying
the heat-mass transfer analogy the corresponding heat transfer
coefficient can be evaluated from the measured mass transfer
rate for the cases of the same boundary conditions. In the
present research, all mass transfer results were obtainted at
the same exit Reynolds Number (Re2=397000) and turbulence
intensity (Tu=0.2 %), but the blowing ratio was varied at two
different values, M=0.7 and M=0.8, respectively. On the both
sides of the turbine blade without the presence of the film
cooling affected zone, the static pressure distribution was
measured in order to predict the boundary layer flow field. The
measured results show that the streamwise distribution of the
spanwise-averaged mass transfer rate with a film cooling, was
much larger than that without a film cooling for both blowing
ratio. On the nearby region of blade leading edge, it was found
a strongly periodic spanwise distribution of the local mass
transfer rate. Without the film cooling, some periodic spanwise
variation were found in some regions over both surfaces of the
turbine blade [Chen(1992)], but they are gone for the cases
with film cooling at the corresponding regions of the blade
surface. This indicates a promotion of free stream turbulence
intensity by ejected air flows causes the disappearance of the
possible Lambda vortice on the convex surface and the Taylor-
Gorlter vortice on the concave surface.
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