شبيه سازي و بهينه سازي فرايند مته كاري توسط نرم افزار DEFORM

چكيده انگليسي :

Coupled CFD FE Analysis for the Exhaust Manifold of EF7 Engine Aghil Askari a askari@me iut ac ir Department of Mechanic Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Mahmoud Farzin m farzin@cc iut ac ir Ebrahim Shirani e shirani@cc iut ac irAbstract Stainless steels are now widely used for automotive exhaust systems driven by the need to increase thedurability of exhaust systems which are subjected to severe conditions and include components of hightechnology such as manifold catalytic converter and particle filter This causes a direct consequence of theeffort to decrease automotive pollutant emissions due to the new environmental regulations throughout theworld During the last few years the increasing use of stainless steel fabricated exhaust systems has led us todevelop new grades to study new production technologies of forming and welding Modern exhaust systemsmust withstand severe cyclic mechanical and thermal loads in an engine cycle Up to now highly loadedparts of exhaust systems are predominantly designed experimentally by means of lengthy and expensivecomponent tests A further shortening of development time without quality loss is possible only by increasingapplication of computer simulation For an engine development program the engine exhaust manifold is acomplex system subjected to thermo mechanical loads The analysis of such a system is critical due to thecomplexity of meeting the structural and flow requirements The use of Computational Fluid Dynamics CFD and Finite Element Analysis FEA are inevitable tools to achieve this The aim of a series of coupledcomputational fluid dynamics finite element CFD FE simulations performed here was to investigate thethermo mechanical behavior of a stainless steel engine exhaust manifold which is in early stage of design Itis going to be designed for the national diesel engine of IPCO EF7 instead of the existing cast iron one Forthis purpose both fluid flow and solid walls are considered simultaneously The exhaust flow situation in theexhaust manifold has been determined using the 3D CFD code FLUENT Furthermore the heat transfercoefficients for the CFD calculation will be evaluated We assume that there is steady state incompressibleand turbulent flow with k turbulence model The overall flow situation in the exhaust manifold is verygood There are no parts in the geometry with high pressure losses or high mach numbers With the help of acode developed in MATLAB the HTC s will be mapped on the FE mesh for the thermo mechanical analysis The thermo mechanical analysis includes a thermal and a stress calculation Since the failure of the exhaustmanifold is mainly due to the geometric constraints of the less expanded inlet flange and cylinder head theanalysis is based on exhaust system model with three dimensional temperature distribution and temperaturedependent material properties Large compressive plastic deformations are observed for the elevatedtemperature of thermal shock cycles The first calculation loop showed a high level of plastic strain primaryat the joints between runners and the flange In the second loop the bore diameters expected a fixing bore offlange were upsized so that the flange can slide free at the gasket plane As result of this change the plasticstrain is decreased strongly Gapping at the gasket between exhaust and cylinder head for the case of thermalexpansion was determinate Keywords Exhaust Manifold CFD Coupling Heat Transfer Thermal Stress

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شبيه سازي و بهينه سازي فرايند مته كاري توسط نرم افزار DEFORM

تابع گشتاور , تابع نيروي محوري , تابع توان