Değişken Viskozite Altında Şaft Hızının Hidrodinamik Yatak-Şaft Sisteminin Rijitlik ve Sönüm Katsayıları Üzerindeki Etkileri

Yıl 2024, ERKEN GÖRÜNÜM, 1 - 1

Abdurrahim Dal

https://doi.org/10.2339/politeknik.1424395

Öz

Ağır yükler ver yüksek hızlarda çalışan hidrodinamik yatak-şaft sistemleri yatakların karakteristik özellikleri sebebiyle önemli rotor dinamiği kararsızlık problemlerine maruz kalırlar. Bu yatakların dinamik özellikleri ve kararlılıkları çalışma esnasında ortaya çıkan ısıdan doğrudan etkilenir. Bu .çalışmada, hidrodinamik yatak ile desteklenmiş yatak-şaft sisteminin dinamik karakteristikleri ve sistemin kararlılığı değşken viskozite altında araştırılmıştır. Yağlayıcının akışı değişken viskozite için Dowson denkleminden türetilmiş ve iki serbestlik dereceli bir yatak-şaft sistemi için pertürbasyon denklemleri elde edilmiştir. Yağ filmindeki ısı transferi 3-boyutlu enerji denklemi ile modellenmiş ve bu modele, yatak çapı yönünde meydana gelen ısı transferi de ısı iletim denklemi ile modellenerek dahil edilmiştir. Teorik modellerin eş zamanlı çözümü için, sonlu farklar metodunu esas alan bir çözüm algortiması geliştirilmiş ve şaft hızının farklı radial boşluğa sahip hidrodinamik yatakların dinamik katsayıları üzerindeki etkilerinin araştırılması için bir dizi benzetim gerçekleştirilmiştir. Yapılan benzetim sonuçları, şaft hızının artması ile yağ sıcaklığının arttığını ve yatağın statik ve dinamik özelliklerini azalttığı ve termal etkinin daha küçük boşluk değerleri için daha etkili olduğu tespit edilmiştir.

Anahtar Kelimeler

değişken viskozite, dinamik karakteristikler, rotor dinamiği

Etik Beyan

Bu makalenin yazar(lar)ı çalışmalarında kullandıkları materyal ve yöntemlerin etik kurul izni ve/veya yasal-özel bir izin gerektirmediğini beyan ederler.

Effects of the Shaft Speed on Stiffness and Damping Coefficients of Hydrodynamic Bearing-Shaft System under Variable Viscosity

Öz

The rotating shaft-hydrodynamic bearings systems operated with high speed and/or heavy load conditions expose serious rotor-dynamics instability problems due to characteristics of the supporting bearings. The stability and the dynamics of these systems, directly relate to the lubricant properties that are directly affect by the heat generation. In this study, the dynamic characteristics of a shaft-hydrodynamic journal bearing and its stability were investigated under variable viscosity. The equations of lubricant flow were derived by Dowson’s equation under variable viscosity, and the perturbation equations were obtained for 2 degrees-of-freedom system. The heat transfers between oil and the journal surface was modelled in a 3-dimensional energy equation, and the heat transfer on the journal structure was also modelled with heat conduction equation. An algorithm based on finite difference scheme with successive over relaxation method was developed to solve the theoretical models, simultaneously, and a serial simulation was performed to investigate the variations of the dynamic coefficients of the bearing-shaft system concerning the rotating speed for different radial clearance values. It was determined that the high speed increases the lubricant temperature, and so the static and dynamic performance characteristics decrease, moreover, this effect is more dominant for the smaller radial clearance.

Anahtar Kelimeler

variable viscosity, dynamic characteristics, rotor dynamic, hydrodynamic bearing

Etik Beyan

The author(s) of this article declare that the materials and methods used in this study do not require ethical committee permission and/or legal-special permission.

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