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In SAE paper 2004-01-1345, author focused on how to use a steady state temperature result obtained by a CFD analysis to conduct a thermal-stress analysis easily with 3 data transfer methods (Direct Conversion Method, Surface Mapping Method and Volume Mapping Method). The advantage and disadvantage of the 3 methods were compared in that paper and a steady state analysis of an engine exhaust manifold was used to show the accuracy, flexibility, efficiency and practicality. In this paper, how to simplify data transfer in a transient coupling is introduced. In transient couplings, 3 troublesome operations always happen. They are 1) multisteps coupling, 2) change of element from low to high order, and 3) estimation of mid node temperature loads of high order elements. In this paper, CFD (Computational Fluid Dynamics) software adopted is SC/Tetra [1], which generates hybrid mesh consisting of tetrahedron, hexahedron, and prism as well as pyramid elements.

Wind tunnel test has been playing a major role in the research and development (R&D) for a racing car. With the aid of computational fluid dynamics (CFD) simulation the development cycle and overall cost are greatly reduced while new and creative ideas can be easily tested on virtual platform with accuracy. In this paper a general overview of the racing vehicle R&D process is provided and a CFD simulation and analysis for a 50% scaled car model is presented in sufficient detail, with an emphasis on addressing its aerodynamic aspects. Good agreements are obtained with a ±5% error between the simulation results and wind tunnel measurements.

Real fluid has viscosity. When fluid flows along a solid surface, the relative velocity between fluid and solid is zero on the solid surface. Getting away from the surface, velocity increases and shearing stress comes into being and forms a kind of friction. Fluid in a pipe losses pressure head when the friction happens as well as the pipe section area changes its size or the flow changes its direction. What is more, inlet box and outlet box will affect the results greatly together with boundary conditions. Namely, pressure drop is divided into 3 parts. They are inlet drop, outlet drop and inner drop of the pipe. Although there are many empiric formulas to estimate the pipe head loss and they are very easy to use, their accuracy is not high enough and the information is not detailed. Additionally these empiric formulas are limited to use for practical pipe with complex shapes.

Using the temperature distribution of solid structures obtained by a CFD (computational fluid dynamics) analysis, thermal-stress analyses can be conducted. In the paper, an FVM (finite volume method) based CFD software is used to solve for the temperature and flow field. Making complex mesh model, it uses a hybrid mesh consists of tetrahedron, hexahedron, prism and pyramid elements. And all variables are defined on nodes of elements. Because the hybrid mesh and variables on nodes are compatible between structural analysis FEM (finite element method) elements and node based CFD FVM elements, not only the temperature distribution of the solid but also the mesh can be directly applied to the thermal-stress analysis. The following three approaches are investigated for the best possible solution of FVM/FEM coupled problems. 1) The mesh and the temperature distribution of CFD are applied in a thermal-stress analysis directly, taking full advantage of the mesh compatibility.

Fluid Structure Interface (FSI) analyses were fast in development during recent years with the constantly advancing progress of computer technology. MpCCI (Mesh based parallel Code Coupling Interface) is a typical product of FSI. MpCCI has been developed at the Fraunhofer-Institute SCAI in order to provide an application-independent interface for the coupling of different simulation codes. Although FSI includes both flow induced displacement and thermal flow induced thermal stress, latter has received less attention. In this paper, temperature results of a transient thermal fluid analysis in a T pipe are used as loads for a nonlinear plastic thermal stress analysis of the pipe. In the nonlinear plastic analysis, linear proximity is used for both plastic region and elastic region. That is to say, 2-line kinematicl hardening law is used to express the stress strain characteristic of the pipe. At the same time, different numbers of load are used and the results are compared.

Researches of multiple physics phenomena become more and more important in industry and academy. Fluid Structure Interface (FSI) is one of these multiple phenomena that happen more often than not. During recent years, numerical analyses of FSI were fast in development with the constantly advancing progress of computer technology. MpCCI (Mesh based parallel Code Coupling Interface) is a typical product of FSI. MpCCI has been developed at the Fraunhofer-Institute SCAI in order to provide an application-independent interface for the coupling of different simulation codes. Although FSI includes both flow induced displacement and thermal flow induced thermal stress, latter has received less attention. One of the authors has studied the methods of data transformation between the thermal fluid analysis and thermal stress analysis, and described the advantages and disadvantages of these methods in weak conjugate analysis [1].

At the initial stage of injection, the inject flow has not yet broken up and in a range of small atmosphere pressure (16∼500KPa), the tip of the inject flow always forms a shape of mushroom. And the umbrella of the mushroom is always very big and the root of it is always very thin, especially when the atmosphere pressure is relatively low (88KPa, or 100mmHg) (1)(2). These phenomena are not known popularly and the reason of mushroom formation is not clear. In this paper, with MARS (Multi-interfaces Advection and Reconstruction Solver) method (3)(4)(5)for simulating free surface, analysis of inject flow is practiced. The phenomena are reproduced and the reason is cleared that the formation of the mushroom is induced by the momentum exchange between the very high speed fuel flow and the very complex air flow.

Heat transfer plays an important role in the conceptual and detail design of cooling system of modern DI engine and has considerable influence over their operational performance and durability. The consequential demand for higher possible heat transfer rates has lead to the very promising concept of providing for a controlled transition from pure single-phase convection to subcooled boiling flow in some high thermal load regions. In order to achieve controlled boiling over a wide range of operation conditions, the detailed flow and heat transfer analysis is essential. CFD simulation incorporating the boiling model is an effective approach for such analysis. Four different boiling heat transfer models are proposed and developed within CFD framework, two based on Division Description Method (DDM), and another two based on Superposition Method (SM).

Human thermal comfort in car cabin has become an important factor to evaluate the success of HVAC (heat ventilation air condition) system. To a HVAC of high quality, it is necessary to produce proper temperatures and air flows at all points including the human body, not just for some specific design conditions. But the current situation is that numerical simulation of HVAC system has still lacked of the link with the thermal source of human body, because of the difficulties in modeling the extremely complicated fluid/thermal system of human body. In this paper, a HVAC system with an accurate thermoregulation model of human body has been simulated in SC/Tetra CFD software, which successfully solves the critical problem coupling the air flow around the body with the human body internal heat transfer physics. Graphical output (including air velocities and temperatures) from SC/Tetra and JOS shows how a particular automotive HVAC system performs.

Because of the contradictions of the downsizing and the serious thermal-load of modern engine, thermal fatigue failure of the engine components easily happens due to excessive temperature gradient and thermal stress. During recent years, with the constantly advancing progress of high performance computer technology, many CFD software codes provide the ability to solve, or take part in the best possible solution of FVM/FEM coupled problems, and Fluid Structure Interaction (FSI) analyses have been developed. However, the unidirectional coupling of thermal flow and thermal stress as well as structural fatigue failure analyses in IC engine applications, especially transient case, has received less attention. In this paper, authors have studied unidirectional FSI in depth, including that transient high speed and high temperature flow strongly affects the engine exhaust manifold. These researches can be used in protection certain fatigue failures for general purpose.