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8332

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تبديل انرژي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1392

ص.: 117ص.: مصور،جدول،نمودار(رنگي)

ص.ع.به فارسي و انگليسي

مهدي نيلي، محمدرضا سليم پور

13/3/93

احمدرضا پيشه ور، محمدرضا توكلي نژاد

مهندسي مكانيك

ID8332

1 چكيده بهبود عملكرد آيروديناميكي ايرفويل از مسايلي است كه از ديرباز بدان توجه شده است در اين رابطه از روش هاي فعال و غير فعال زيادي جهت افزايش كارايي ايرفويل و يا بال هواپيما استفاده شده است استفاده از فالپ ايجاد حفره بر روي ايرفويل ايجاد شيارهاي ريز استفاده از ايرفويل پلهدار استفاده از ايرفويل با لبهي ضخيم و از مواردي است كه در اين باره مورد توجه قرار گرفته است در اين پژوهش بررسي ويژگيهاي جريان در دو روش مورد استفاده جهت بهبود عملكرد ايرفويل ريزو كه ايرفويلي جديد است مورد توجه قرار گرفته است در روش اول از فالپ تيغه اي و در روش دوم اثرات استفاده از ايرفويل با لبهي ضخيم و اضافهكردن كويتي باز به آن جهت كاهش نير وي دراگ مورد توجه قرار گرفته است در واقع عملكرد آيروديناميكي ايرفويل مانند ميزان نيروي دراگ و نيروي ليفت و با استفاده از ابزار اندازهگيري مخصوص بهخود مانند اندازهگيري نيروها با باالنس نيرويي يا بررسي توزيع فشار با استفاده از سنسور فشار مورد بررسي قرار مي گيرد در اين پژوهش تنها اثرات استفاده از اين موارد بر روي ويژگيهاي ميدان جريان ايرفويل مانند فركانس ريزش گردابه و عدد استروهال توزيع سرعت لحظهاي و ميانگين بر روي ايرفويل توزيع ورتيسيته سرعت در مقاطع مختلف و مورد تحليل و بررسي قرار ميگيرد براي اندازهگيري سرعت از تكنيك تجربي PIV استفاده مي شود در اين روش ذراتي به سيال اضافه شده با استفاده از نور ليزر رديابي ميشوند سپس توسط دوربين فيلمبرداري از آنها عكسبرداري ميشود با پردازش تصوير اين عكسها سرعت سيال در هر نقطه بدست ميآيد كلمات كليدي ايرفويل ريزو ميدان سرعت فالپ تيغهاي ايرفويل با لبهي ضخيم تكنيك PIV

111 Experimental Study of Flap and Cavity Effects on Flow Field over Riso Airfoil Using PIV Technique Gholamhosein Taherian Gh taherian@me iut ac ir Date of Submission 0231 20 9 Department of mechanical Engineering Isfahan University of Technology Isfahan 65348 61333 Iran Degree M Sc Language FarsiSupervisor Mehdi nili m nili@cc iut ac irMohammadreza salimpour salimpour@cc iut ac irAbstractImproving the aerodynamic performance of airfoils is a well known problem in aerodynamics Many active andpassive methods have been used in order to increase the improvement of airfoil s performance Using flap cavity riblet steps on airfoils with thick blunt trailing edge are some of these methods In this thesis thefeatures of flow field over the Riso airfoil are studied with two methods of improving the aerodynamicperformance in low speed wind tunnel The effects of gurney flap and adding open cavity in a thick blunttrailing edge airfoil has been studied to decrease drag force Actually the amount of drag and lift force aremeasured by using special measurement tools such as force balance and pressure sensor In this thesis only theeffects of flap and cavity on the features of flow field such as vortex shedding frequency strouhal number instantaneous and mean velocity distribution vorticity distribution different section velocity profile and etc hasbeen studied Experiments were done at different Reynolds number and for three angles 2 4 32 degree Particle Image Velocimetry technique which has high temporal and spatial resolution has been used in thisresearch in order to reach a better insight to the structure and dynamics of this unsteady and complex flow filed In this technique many particles have been seeded to the flow and have been detected with laser light Then thevelocity of flow is measured in each point by using image processing of pictures obtained by camera The experimental method was validated with real results of flow over a circular cylinder Strouhal number anddrag force were compared that shows good agreement Moreover the result of image processing software wasvalidated with credible image processing results For acquire skills to do PIV technique at first the phenomenon of free convection around a metal cylindricalwith uniform heat flux is experimentally investigated using PIV technique The experimental tests are performedin a cubic container full of liquid water with free surface A metal rod horizontally passes through the container To create a two dimensional flow two parallel planes are inserted in the container and then the metal rod ispassed through it The tests are performed for different heights of water and their results are compared with eachother The results show that the flow field is strongly oscillatory and unsteady In the second part of thesis results show that use of gurney flap decreases momentum behind the airfoil andincrease the length of wake region so the drag force increases Moreover it decreases the vortex sheddingfrequency and increases stability Flow over a thick blunt trailing edge airfoil also shows that use of this methoddelayed flow separation on the surface of airfoil When open cavity added to thick blunt trailing edge airfoil two vortex behind airfoil disappears and the stability of flow increases Momentum of flow behind the airfoil forsmall attack angle decreases so the drag force for small attack angle decreases Keywords

مهدي نيلي، محمدرضا سليم پور

احمدرضا پيشه ور، محمدرضا توكلي نژاد