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首页> 外文会议>ASME(American Society of Mechanical Engineers) Turbo Expo vol.4; 20060506-11; Barcelona(ES) >CALCULATIONS OF COOLED TURBINE EFFICIENCY
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CALCULATIONS OF COOLED TURBINE EFFICIENCY

机译：涡轮冷却效率的计算

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摘要

The efficiency of a cooled turbine stage has been discussed in the literature. All proposed definitions compare the actual power output with an ideal output, which has to be determined; but usually one of two definitions has been used by turbine designers. In the first, the so-called Hartsel efficiency, the mainstream gas flow and the various coolant flows to rotor and stator are assumed to expand separately and isentropically to the back pressure. In the second it is assumed that these flows mix at constant (mainstream) gas pressure before expanding isentropically (sometimes the rotor coolant flow is ignored in this definition). More recently it has been suggested that a thermodynamically sounder definition is one in which the gas and coolant flows mix reversibly and adiabatically before isentropic expansion to the back pressure. In the current paper these three efficiencies are compared, for a typical stage - the first cooled stage of a multistage industrial gas turbine. It is shown that all the efficiencies fall more or less linearly with increase of the fractional (total) coolant flow. It is also shown that the new definition of efficiency gives values considerably lower than the other two efficiencies, which are more widely used at present. Finally, the various irreversibilities associated with the flow through a cooled turbine are calculated. Although all these irreversibilities increase with the fractional coolant flow, it is shown that the "thermal" irreversibility associated with film cooling is higher than the other irreversibilities at large fractional coolant flow.
机译：文献中已经讨论了冷却涡轮机级的效率。所有提出的定义都将实际功率输出与理想功率进行比较，该理想功率必须确定。但通常涡轮设计人员会使用以下两种定义之一。首先，假设所谓的Hartsel效率，主流气流和流向转子和定子的各种冷却剂分别膨胀并与背压等熵膨胀。在第二个中，假设这些流在等熵膨胀之前在恒定（主流）气压下混合（有时在此定义中忽略了转子冷却剂流）。最近，已经提出了一种热力学上更合理的定义，即在等熵膨胀至背压之前，气体和冷却剂流可逆地和绝热地混合。在当前的论文中，比较了典型阶段（多级工业燃气轮机的第一个冷却阶段）的这三种效率。结果表明，所有效率都随分数（总）冷却剂流量的增加而线性下降。还显示了效率的新定义所给出的值大大低于当前更广泛使用的其他两个效率。最后，计算与通过冷却涡轮的流量相关的各种不可逆性。尽管所有这些不可逆性都随着分数冷却剂流量的增加而增加，但是显示出与膜冷却相关的“热”不可逆性高于在分数冷却剂大流量下的其他不可逆性。

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