ارزيابي عملكرد مدل هاي مختلف اغتشاشي براي تحليل جريان آيروديناميك حول بالواره چند الماني با استفاده از يك حلگر آزاد جريان سيال

چكيده انگليسي :

Performance Evaluation of Different Turbulence Models for Analyzing Aerodynamic Flows around a Multi Element Airfoil Using an Opensource CFD Solver Saeide Mohammadi Saeide mohammadi@me iut ac ir Date of Submission 1 22 2014 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mahmud Ashrafizadeh mahmud@cc iut ac ir Abstract The flow analysis around various kinds of airfoils is one of the problems that have long been considered by researchers One of the important aerodynamic parameters is the maximum lift coefficient The higher the maximum lift coefficient the lower the airplane landing velocity would be and also the airplane could take off sooner which requires a shorter runway length In addition to this the high maximum lift coefficient decreases the airplane fuel consumption and increases the ability of it to carry more cargo The most effective way to increase the maximum lift coefficient is to use multi element airfoils with variable curvature However the use of high lift systems is costly due to their expensive manufacturing in addition the analysis of the flow physics is very complicated due to interaction and confluence of fluid flow around each element The aim of this study is to improve the reliability of the flow simulation around high lift devices In this study the turbulent flow around multi element airfoils on a landing configuration was simulated using an opensource CFD tool the OpenFOAM software Seven different turbulence models have been used in optimal simulation conditions to evaluate the performance of models for the prediction of the complex flow around a three element airfoil The models are the SpalartAllmaras the RNGkEpsilon the realizableKE the kOmegaSST the NonlinearKEShih the LienCubicKE the kEpsilon turbulence models In this study the effects of grid and domain size on the accuracy of the simulation results are investigated and the optimal values are chosen for the flow analysis around the multi element airfoil The resulting surface pressure coefficients of different turbulence models are compared with those of available experimental data and also with those of number of valid numerical results In steady two dimensional simulation an excellent agreement between obtained computational and experimental surface pressures is observed for the SpalartAllmaras and the RNGkEpsilon models but only moderately good agreement is seen in other models predictions The ability of models to predict the flow separation point on the trailing edge of the flap and the stagnation point on the leading edge of the slat are also investigated The models produce similar results in most cases Generally the difference between the predictions of the different models is less than the difference between the computational and experimental data Among these models the SpalartAllmaras the kOmegaSST and the RNGkEpsilon have closer results to the experimental data in terms of predicting the separation point The NonlinearKEShih model predicts separation point earlier and the other models predict the separation point later on the trailing edge of the flap Although more simplifications are used in the present study compared to the simulation conditions used in other studies the accuracy of our results is comparable to those of other numerical as well as experimental data in the literature In particular the SpalartAllmaras and the RNGkEpsilon models predict the flow separation more accurately than the other numerical results when compared with experimental data Keywords Multi element airfoil Turbulence models Flow separation OpenFOAM Flap SlatPDF created with pdfFactory Pro trial version www pdffactory com

محمدي، سعيده

ارزيابي عملكرد مدل هاي مختلف اغتشاشي براي تحليل جريان آيروديناميك حول بالواره چند الماني با استفاده از يك حلگر آزاد جريان سيال

جريان آشفته , ايرفويل سه الماني , OpenFOAM , جدايش