ﺗﺄﺛﯿﺮ ﻋﻤﻖ ﺑﺎﻓﺖ ﻫﺎي ﺳﻄﺤﯽ ﭘﻮﺳﺘﻪ ﺑﺮ ﻋﻤﻠﮑﺮد ﺣﺎﻟﺖ ﭘﺎﯾﺪار ﯾﺎﺗﺎﻗﺎن ﻫﺎي ژورﻧﺎل ﮔﺎزي ﻏﯿﺮﻣﺪور دو ﻟُﺐ

Effect of Shell Surface Texture Depth on the Steady State Performance of Noncircular Two Lobe Gas Journal Bearings

ﺗﻮﺳﻌﻪ روزاﻓﺰون ﺑﮑﺎرﮔﯿﺮي ﯾﺎﺗﺎﻗﺎن ﻫﺎي ژورﻧﺎل ﮔﺎزي ﺑﻪ ﻋﻨﻮان ﺗﮑﯿﻪ ﮔﺎه اﺟﺰاء دوار ﺑﻮﯾﮋه در ﺳﺮﻋﺖ ﻫﺎي ﺑﺎﻻ ﺳﺒﺐ ﺷﺪه ﺗﺎ ﭘﮋوﻫﺶ ﺑﺮاي دﺳﺘﯿﺎﺑﯽ ﺑﻪ ﻣﺴﯿﺮﻫﺎي ارﺗﻘﺎء ﻋﻤﻠﮑﺮد آﻧﻬﺎ در دﻫﻪ ﻫﺎي اﺧﯿﺮ از اﻫﻤﯿﺖ وﯾﮋه اي ﺑﺮﺧﻮردار ﮔﺮدد. ﺗﻐﯿﯿﺮ در ﺳﺎﺧﺘﺎر ﻫﻨﺪﺳﯽ اﯾﻦ ﮔﺮوه از ﯾﺎﺗﺎﻗﺎن ﻫﺎ ﺑﺎ اﯾﺠﺎد ﺑﺎﻓﺖ ﻫﺎي ﺣﻔﺮه اي ﻣﻨﻈﻢ روي ﺳﻄﺢ داﺧﻠﯽ ﭘﻮﺳﺘﻪ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺗﻮﺳﻌﻪ روش ﻫﺎي ﻧﻮﯾﻦ ﻣﺎﺷﯿﻨﮑﺎري و ﻟﯿﺘﻮﮔﺮاﻓﯽ، از ﺟﺪﯾﺪﺗﺮﯾﻦ روش ﻫﺎي ﭘﯿﺸﻨﻬﺎدي ﻣﺤﻘﻘﺎن ﺣﻮزه رواﻧﮑﺎري در راﺳﺘﺎي ﺑﻬﺒﻮد ﻋﻤﻠﮑﺮد اﯾﻦ ﻧﻮع از ﺗﮑﯿﻪ ﮔﺎه ﻫﺎ ﻣﯽ ﺑﺎﺷﻨﺪ. در ﭘﮋوﻫﺶ ﺣﺎﺿﺮ، ﺗﺎﺛﯿﺮ ﻋﻤﻖ ﺣﻔﺮه ﻫﺎي اﺳﺘﻮاﻧﻪ اي ﺳﻄﺤﯽ ﺑﺮ ﻋﻤﻠﮑﺮد ﭘﺎﯾﺪار ﯾﺎﺗﺎﻗﺎن ﻫﺎي ژورﻧﺎل ﮔﺎزي ﻏﯿﺮﻣﺪور دوﻟُﺐ ﺑﺮرﺳﯽ ﺷﺪه اﺳﺖ. ﺑﻪ اﯾﻦ ﻣﻨﻈﻮر ﻣﻌﺎدﻟﻪ رﯾﻨﻮﻟﺪز ﺣﺎﮐﻢ ﺑﺮ رواﻧﮑﺎري ﯾﺎﺗﺎﻗﺎن ﻫﺎي ژورﻧﺎل ﮔﺎزي ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺗﻐﯿﯿﺮات ﺿﺨﺎﻣﺖ ﻓﯿﻠﻢ رواﻧﮑﺎر، ﻣﺘﺄﺛﺮ از ﺣﻀﻮر ﺑﺎﻓﺖ ﻫﺎي ﺳﻄﺤﯽ ﭘﻮﺳﺘﻪ، اﺻﻼح و ﺑﺎ روش ﺣﻞ ﻋﺪدي اﺟﺰاء ﻣﺤﺪود ﺗﺤﻠﯿﻞ ﮔﺮدﯾﺪه اﺳﺖ. ﻧﺘﺎﯾﺞ ﺑﯿﺎﻧﮕﺮ آﻧﺴﺖ ﮐﻪ اﯾﺠﺎد ﺑﺎﻓﺖ ﻫﺎي اﺳﺘﻮاﻧﻪ اي ﺑﻮﯾﮋه ﺑﺎ ﻋﻤﻖ ﻫﺎي اﻧﺪك در ﻟُﺐ ﺗﺤﺘﺎﻧﯽ ﺑﺮ ﺗﻐﯿﯿﺮ ﭘﺎراﻣﺘﺮﻫﺎي ﻋﻤﻠﮑﺮد ﻣﺠﻤﻮﻋﻪ ﻧﻈﯿﺮ ﭘﺮوﻓﯿﻞ ﻓﺸﺎر ﺗﺎﺛﯿﺮﮔﺬارﺗﺮ اﺳﺖ. ﺑﺎ ﻋﻤﯿﻖ ﺷﺪن ﺑﺎﻓﺖ ﻫﺎ ﺑﻮﯾﮋه ﺑﺎ اﻓﺰاﯾﺶ ﻏﯿﺮﻣﺪوري ﯾﺎﺗﺎﻗﺎن، ﺑﺎر ﻗﺎﺑﻞ ﺣﻤﻞ و اﺗﻼف اﻧﺮژي رواﻧﮑﺎر ﮐﺎﻫﺶ ﯾﺎﻓﺘﻪ و ﻣﯿﺰان زاوﯾﻪ وﺿﻌﯽ راﺳﺘﺎي ﻗﺮارﮔﯿﺮي روﺗﻮر روﻧﺪي اﻓﺰاﯾﺸﯽ را ﻧﺸﺎن ﻣﯽ دﻫﺪ؛ ﻫﻤﭽﻨﯿﻦ ﺑﺮ اﺳﺎس ﻧﺘﺎﯾﺞ در ﻣﻘﺎدﯾﺮ ﭘﺮﯾﻠﻮد ﻣﺘﻔﺎوت ﯾﺎﺗﺎﻗﺎن، اﻧﺘﺨﺎب ﻋﻤﻖ ﺑﻬﯿﻨﻪ ﺑﺎﻓﺖ ﻫﺎ، دﺳﺘﯿﺎﺑﯽ ﺑﻪ ﻋﻤﻠﮑﺮد ﻣﻄﻠﻮب ﺗﺮ ﻣﺠﻤﻮﻋﻪ ﺗﮑﯿﻪ ﮔﺎﻫﯽ را ﻣﻤﮑﻦ ﻣﯽ ﺳﺎزد.

Due to the increasing development of using gas journal bearings as a support for rotating components in different equipment, improving their performance has been the subject of many recent studies. Different geometric design of bearings by creating regular textures on the surfaces due to the development of new machining methods and lithography is the latest techniques proposed by lubrication researchers. In this study, the effects of cylindrical dimples depth on the steady-state performance of two lobe noncircular gas journal bearings are investigated. For this purpose, governing Reynolds equation is modified and analyzed by FEM due to changes in the thickness of the lubricant film in presence of the surface textures. Results indicate that the creation of shallow cylindrical textures on the lower lobe is more effective on the performance of the considered bearings. As the cylindrical textures deepen, especially at lower value of preload factor, load carrying capacity and energy dissipation of the gas lubricant decrease and the attitude angle of the rotor center shows an inverse trend. Also, in different preload or bearing noncircularity values, choosing the optimal depths of cylindrical textures enhances the performance parameters of investigated bearing support system.