advanced simulation technologies Vapor rising from the surface of a quenched cylinder head. FIRE® simulates the boiling of the coolant and cooling of the structure simultaneously. 2 1 F O C U S SAVING COST AND IMPROVING QUALITY BY USING AVL FIRE® FOR QUENCHING Quenching is the forced cooling of heated parts to ambient temperature. It is commonly applied in the heat treatment process of cast parts. The goal is the development of material properties and residual stresses that can sustain high operational loads. A typical example for a complex cast component exposed to very high load is an engine cylinder head. Under unfavorable conditions cracks can occur, which may lead to failure, causing consumer annoyance and warranty issues. While in the recent past the failure rate increased through downsizing and weight reduction measures, the industry’s interest in ways to optimize the heat treatment naturally grew. To respond to this need, AVL developed an exciting solution by applying its 3D CFD simulation software FIRE®. It accurately reflects the effects of different boiling regimes during the quenching process. The result enables the precise calculation of the transient temperature field in quenched parts, which is a precondition for determining the residual stresses and changes in material properties. It makes it possible to choose the right part orientation during quenching and selecting the optimum coolant temperature. It also potentially indicates the need for coolant flow enforcement by means of nozzles or stirrers. > Today AVL offers a unique, refined and acknowledged solution employed by many industry leaders, such as FORD, HMC, VW and NEMAK, to ensure maximum product quality and highest component life time. < OPTIMIZATION OF FUEL INJECTION NOZZELS WITH AVL BOOST / FIRE® COUPLED SIMULATIONS In order to achieve target values, such as engine performance, efficiency and engine out emissions the precise control of fuel injection is crucial. Production tolerances, especially for small size injection nozzles, need to be overcome because even the smallest deviations may have a significant effect on the mixture formation, resulting in deteriorating engine performance. As the production process of spray holes is hard to control, hole-to-hole variations are common. This causes an asymmetric discharge into the combustion chamber eventually affecting every process taking place there: ignition, combustion / heat release, emissions formation, heat transfer. “Coupled BOOST HYDSIM/FIRE® simulations form a virtual test bed enabling the detailed definition and optimization of an injection system. At the same time, the influence of injection nozzle production tolerances on effectiveness and efficiency of the combustion process can be investigated”, David Greif, Product Manager for AVL FIRE®, told Focus, outlining the two-fold benefit of this kind of coupled simulation. While one-dimensional BOOST models reflect the complete injection system from the tank through the rail to the injection nozzle, the FIRE® model focuses on the three-dimensional calculation of the fluid flow through the nozzle tip. Coupled simulations reproduce both longitudinal and lateral needle displacements and thus can detect even the slightest geometrical inaccuracy in the nozzle. Asymmetric fuel delivery will be reflected in subsequent in-cylinder flow simulations impacting the combustion process. “Coupling BOOST and FIRE® enables the development of a robust nozzle design – a pre-condition for a reliably working combustion engine and traceable performance data,” adds David Greif. <
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