冷却对燃气透平的熵增及透平效率影响的研究

运用修正的解析模型计算得到叶片冷却空气需求量和温度分布,并从热力学第二定律角度出发,阐述了动、静叶冷却过程的熵增情况,详细分析了冷却空气在冷却通道内的内部摩擦、导热损失模型以及冷却空气与燃气掺混时的内能和动能损失模型.对不同定义下的燃气轮机透平效率进行了比较、探讨,研究了叶片冷却对透平效率的影响,并对其进行了修正.算例结果表明,冷却导致的一系列不可逆熵增使得透平效率发生了2％ -3％左右的下降.因此,在研究中需对冷却导致的透平效率变化进行修正,使得结果更加准确.

Research of Impact of Cooling on Entropy Creation and Turbine Efficiency

The cooling air required for blade and the temperature distribution of the blade surfaces are calculated by means of modified analytical model,and the entropy creation of stationary blades and rotating blades in the process of cooling is elaborated by using the second law of thermodynamics.The model of cooling air’s friction and heat transfer process in the cooling channel and mixing process are analyzed in detail.The different definitions of turbine efficiency are compared,the blade cooling’s effect on turbine efficiency is investigated,and turbine efficiency is revised.The result of example shows that the irreversible entropy due to cooling leads to the turbine efficiency decrease by about 2%-3%.Therefore,it is necessary to modify the turbine efficiency’s change due to the cooling in order to make the result more accurate.