Heat Transfer Committee Best 1994 Paper Award: Experimental and Theoretical Investigations of Heat Transfer in Closed Gas-Filled Rotating Annuli II
Heat Transfer Committee Best 1994 Paper Award: Experimental and Theoretical Investigations of Heat Transfer in Closed Gas-Filled Rotating Annuli II
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传热委员会 1994 年最佳论文奖：封闭充气旋转环 II 中传热的实验和理论研究
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
U. Krüger
中科院分区：
文献类型：
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作者：
D. Bohn;R. Emunds;V. Gorzelitz;U. Krüger
通过提高涡轮进口温度来提高热效率是燃气轮机发展的重要目标之一。由于温度较高，涡轮机的叶片和叶片必须冷却，而且对转子最热区域的机械和热应力部件的知识也非常感兴趣。对包含封闭的充气腔的燃气轮机转子内温度分布的预测，例如在两个圆盘之间，必须考虑在这些腔中遇到的换热条件。在完全封闭的环空中，由于离心力场中密度分布的不均匀，不存在强迫对流，但存在较强的自然对流。在Bohn等人中。(1994)，对具有纯向心热流的旋转空腔进行了实验和数值研究。本文对纯轴向热流进行了研究。设计了一套实验装置，以实现燃气轮机转子腔内经常遇到的大范围(2.108<；ra<；5.1010)的fRa数。在进行实验的同时，还进行了数值计算。将数值计算结果与实验数据进行了比较。在不改变Ra的情况下，数值格式也被用来考虑Re对换热的影响。这种影响不能通过实验来指出，因为不可能改变所用环带的Re-Ra特性。结果表明，除高Ra外，数值计算结果与实验数据吻合较好，数值计算得到的换热比实验结果要高。一个原因可能是，在实验中，内外圆柱壁并不是真正绝热的，这是数值过程中使用的假设。此外，对于高Ra，二维流型的假设可能变得无效。用三维版本的数值程序研究了三维效应的影响。与径向定向换热相比，Nu要小得多，并且对Re有很强的依赖性，而径向换热仅受Re的影响较小。
Increasing the thermal efficiency by higher turbine inlet temperatures is one of the most important aims in the area of gas turbine development. Because of the high temperatures, the turbine vanes and blades have to be cooled, and also knowledge of the mechanically and thermally stressed parts in the hottest zones of the rotor is of great interest. The prediction of the temperature distribution in a gas turbine rotor containing closed, gas-filled cavities, for example, in between two disks, has to account for the heat transfer conditions encountered in these cavities. In an entirely closed annulus, forced convection is not present, but a strong natural convection flow exists, induced by a nonuniform density distribution in the centrifugal force field. In Bohn et al. (1994), experimental and numerical investigations on rotating cavities with pure centripetal heat flux had been carried out. The present paper deals with investigations on a pure axially directed heat flux. An experimental setup was designed to realize a wide range ofRa numbers (2.10 8 < Ra < 5.10 10 ) usually encountered in cavities of gas turbine rotors. Parallel to the experiments, numerical calculations have been conducted. The numerical results are compared with the experimental data. The numerical scheme is also used to account for the influence of Re on heat transfer without changing Ra. This influence could not be pointed out by experiments, because a variation of the Re-Ra characteristic of the employed annuli was not possible. It was found that the numerical and experimental data are in quite good agreement, with exception of high Ra, where the numerical scheme predicts higher heat transfer than the experiments show. One reason may be that in the experiments the inner and outer cylindrical walls were not really adiabatic, an assumption used in the numerical procedure. Moreover, the assumption of a two-dimensional flow pattern may become invalid for high Ra. The influence of three-dimensional effects was studied with the three-dimensional version of the numerical code. In contrast to the radial directed heat transfer, it was found that Nu is much smaller and depends strongly on Re, whereas the radial heat transfer is only weakly influenced by Re.