پديد آورنده :
براتچي، فرهاد
عنوان :
شبيه سازي عددي ارتعاش يك استوانه در جريان با عدد رينولدز پايين با استفاده از روش بر هم نهادن شبكه ها
مقطع تحصيلي :
كارشناسي ارشد
گرايش تحصيلي :
تبديل انرژي
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك
صفحه شمار :
نه، 87، [II] ص.: مصور، جدول، نمودار
استاد راهنما :
محسن ثقفيان
استاد مشاور :
ابراهيم شيراني چهار سوقي
توصيفگر ها :
شبكه استاتيكي ، ديناميكي , نقاط خالي ، پر , گام برداري قطري
استاد داور :
محمد سعيد سعيدي، احمدرضا پيشه ور
تاريخ ورود اطلاعات :
1396/10/27
چكيده فارسي :
به فارسي و انگليسي : قابل رويت در نسخه دبجيتالي
چكيده انگليسي :
AbstractIn this numerical study overset grid method has been used for investigating the flow fieldaround an oscillating cylinder In the first chapter of this thesis forced oscillation of a cylinder perpendicular to the streamin low Reynolds number has been investigated It was observed that in a range ofexcitation frequencies vortex shedding frequency of cylinder is equal to excitationfrequency This phenomenon is referred as lock in It is interesting that the frequency ofvortex shedding from stationary cylinder is placed in middle of this range and almost inthis frequency the mean value of drag coefficient reaches its maximum In second chapter flow induced vibrations of an elastic cylinder in a low Reynolds numberflow has been investigated In first section of this chapter flow induced vibrations of atwo degrees of freedom elastic cylinder has been studied It was considered that amplitudeof vibrations perpendicular to the stream is grater than stream wise amplitude and in mostof cases this difference reaches one order of magnitude In addition for light cylinders in arange of natural frequencies vortex shedding frequency from rigid cylinder is placed inthis range vortex shedding frequency in other words oscillation frequency of cylinderperpendicular to flow field is close to natural frequency of cylinder It was interesting thata gradual increase in natural frequency of cylinder in this rang makes a gradual deviationin vortex shedding frequency from natural frequency of cylinder This phenomenon isreferred as soft lock in It was considered that in this range of natural frequencies amplitude of cylinder vibrations reaches its maximum value In second section of thischapter the same cylinder same material and dimension with one degree of freedom hasbeen studied In this case soft lock in has been observed as before It was realized that for acylinder with two degrees of freedom having value of natural frequency far from soft lockin range one can use one degree of freedom analysis instead In the next section the effectof mass ratio coefficient on two degrees of freedom oscillations has been analyzed Themass of the cylinder considered in this section was 10 times more than the previous casesand existence of lock in was observed in this case It was understood that existence of lockin or soft lock in depends on mass ratio coefficient only In the last section the effect ofreduced damping parameter has been studied Presence of soft lock in condition wascaptured in this case too
استاد راهنما :
محسن ثقفيان
استاد مشاور :
ابراهيم شيراني چهار سوقي
استاد داور :
محمد سعيد سعيدي، احمدرضا پيشه ور