8789

8150

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تبديل انرژي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1392

دوازده،81ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محمود اشرفي زاده

محسن دوازده امامي

8/2/93

محمدرضا سليم پور، احمد صداقت

مهندسي مكانيك

ID8150

9 شرايط مرزي براي معادله انتقال شرايط مرزي براي معادالت ناوير استوكس حل دستگاه معادالت 3 5 روشهاي مستقيم روشهاي تكرار براي حل دستگاه معادلههاي جبري الگوريتم حل معادالت ناويراستوكس 3 6 معادله فشار الگوريتم كوپل فشار سرعت فصل چهارم نتايج مقدمه 4 1 ايرفويل مورد بررسي 4 1 شبكه 4 9 بررسي اثر گسستهسازي بر دقت حل 4 3 جابهجايي گراديان سرعت گراديان فشار ديفيوژن گراديان عمودي سطح ميانيابي روش گسسته سازي نهايي تابع ديواره 4 4 مقايسه مدل آشفتگي 4 5 روش حل معادالت 4 6 ضريب زير تخفيف 4 7 زاويه حمله صفر 4 8 زاويه حمله چهار درجه و ماخ 1 0 4 2 4 01 عدد ماخ 51 0 4 11 عدد ماخ 9 0 فصل پنجم نتيجه گيري و پيشنهادات نتيجه گيري 5 1 پيشنهادات 5 9 مراجع 27 چكيده 98 نه

83 Numerical Simulation of Incompressible Flows Around a Supercritical Airfoils Using OpenFoam Shirin Derikvand s derikvand@me iut ac ir Date of Submission 2013 1 21 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors Mahmud@cc iut ac irAbstractOpenFoam is a free open source CFD software package which can be used to solved a wide variety ofproblems It has been developed by OpenCFDLtd at ESI group Considering the opensource nature of theOpenFoam software users who know C and are koowiledible in their field of study may alter and furtherdevelop the capabilities of the software Previous researches indicated that the error aerodynamiccoefficients predicted for external flows which are obtainded by OpenFoam even at very low Machnumbers 0 08 are still rather high compared to those of the wind tunnel testing as well as those of otheravailable softwares such as Fluent One of the important issues in the process of numerical simulation offluid flow that must be taken into account is the method of discretization of the governing equations Finite volume method is used as the discretization scheme in the OpenFoam software While thefundamentals of the finite volume discretisation are well understood discretization of the terms of theNavier Stokes equations and the schemes that definitively determine the accuracy of a method as well ascan guarantee the convergence of the solution have been a subject of continual intense research Thus theeffect of discretization schemes on the solution accuracy of the incompressible flow regime is examined toreduce the error of aerodynamic coefficients which is obtained by the OpenFoam software Due to theimportance of the supercroitical airfoils in airline industry incompressible flows around the SC 2 0714airfoil is investigated at different angles of attack and mach numbers In this study the effect of usingvarious discretization schemes including upwind schemes linear schemes TVD and NVD schemes arestudied The second order LineareUpwind scheme is the most accurate for the discretization of thedivergence term The discretization scheme of the gradient especially the pressure gradient has asignificant influence on the accuracy of the solution The QUICK scheme for the velocity gradiend as wellas the leastSquares scheme for pressure gradient have an excellent accuracy An interpolation scheme and asurface normal gradient scheme are required for the laplacian term discretization The second order Linearinterpolation scheme is more accurate than the other schemes The corrected scheme is used for the surfacenormal gradient Wall functions are usually used to avoid fine grids around the walls reduce thecomputational cost Consequently approximate solutions are used instead of the detailed solution of theequations near the wall region Accordingly applying these wall functions has a considerable effect on thenumerical error reduction It is realized that the UWallFunction is the most accurate wall function to use inthe OpenFoam software The simpleFoam solver is employed to solve the flow Studies showed that theSpalart Allmaras turbulence model has less error in low Mach numbers 0 1 However the more complexturbulence model i e k omegaSST is more proper and accurate when Mach number as well as the angleof attack In the present study the error of drag coefficient was reduced to 2 8 compared to 34 58 errorreported by others by considering an appropriate discretization scheme for terms of the governingequations and selecting a suitable turbulence model and wall function Keywords OpenFoam Supercritical airfoil Scheme Drag Incompressible

محمود اشرفي زاده

محسن دوازده امامي

محمدرضا سليم پور، احمد صداقت