Cemil KURTCEBE, M. Zeki ERİM

Türbin uygulamaları için eksenel simetrik kanalda viskoinelastik akışkan akımı

Bu çalışmada, gaz türbinine ait disk elemanının viskoinelastik bir akışkan ile soğutulmasına ilişkin bir yöntem sunulmuştur. Gerçekten gaz türbinlerinin üretebilecekleri enerjiyi türbin boyutlarını değiştirmeden arttırmak için ya disk ve pallerin imalatında kullanılan malzemenin kalitesini iyileştirmek veya anılan elemanları soğutmak gerekir. Bu çalışmada ikinci yönteme ait bir inceleme verilmiştir. Bu maksatla hız ve sıcaklık dağılımları tayin edilmişlerdir. Nu Nusselt sayısı ise, K viskoinelastik parametrenin, Re Reynolds sayısının ve Pr Prandtl sayısının fonksiyonu olarak elde edilmiştir. Bu yapılırken temel denklemler pertürbasyon yöntemiyle lineer hale getirilmişlerdir. Netice olarak K viskoinelastik parametrenin artmasıyla f "(0) duvar sürtünme parametresinin azaldığı. Nu Nussell sayısının ise arttığı gösterilmiştir.

Viscoinelastic fluid flow in an axisymmetric channel for turbine cooling application

In the present paper, a method for cooling turbine disks with a non-newtonian Viscoinelastic fluid is analyzed. Indeed, in order to increase the amount of energy produced by the gas turbine without changing the dimensions of the engine, there are two possibilities used in practical applications. One of them is to increase the thermal resistance properties of the turbine disk or blade material. The other possibility is to cool the turbine blade or disk element of the turbine engine. In this paper, the latter method is applied in the case of a viscoinelastic coolant fluid. However, the cooling process gives a rise to excess energy consumption which decreases the overall efficiency oj the turbine. By means of drag reduction the energy consumption can be economized and turbine engine efficiency can be improved. For this reason it seems reasonable to reconsider the cooling problem of the turbine disk for viscoinelastic fluid flow since it is well known that viscoinelastic fluids have drag reducing property. For this sake the velocity and temperature fields are obtained numerically by applying a perturbation method. The Nussell number is determined as a function of the cross viscosity parameter K, the Reynolds number Re, and the Prandtl number Pr. As a result, it is shown that increasing the cross viscosity parameter K decreases the wall friction parameter f "(0) and increases the Nusselt number.

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