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<p class="AMSmaintext"><span lang="EN-GB">The microstructure evolution of 20Cr steel spider in the cold forging process was simulated and analyzed by CA method, and verified by the experimental results. The CA simulation results show that the grain size becomes smaller with an increase of forging reduction. When the reduction is 60%, the grain size is the smallest. After that, the microstructure is inhomogeneous. At the same forging reduction, the microhardness at the root of the pin is higher than that at the head of the pin. It is well agreed with the distribution of the effective strain. The CA results agree well with the experimental data in terms of microstructure evolution and microhardness distribution, suggesting that the CA model is a reliable numerical approach for predicting microstructure evolution during cold forging for 20Cr steel spider.</span></p>

The layout of closed-couple catalyst converter in internal combustion engine exhaust system is one of important way to reduce vehicle emission. CFD method based on finite volume method is adopted to numerical simulate flow distribution in the entrance of closed-coupled catalytic converter and applying business software of FLUENT to clarity the flow uniformity of inlet to ensure catalytic converter work efficiently and meet regulations. The flow field uniformity of entrance were studied and analyzed. Research finds that the shape of manifold has effect on dispersion of velocity in entrance and dispersion of velocity has a relatively strong correlation with pulsation flow. The flow reverse in junction deflect the air flow that flow into the entrance of closed-couple catalyst converter. Calculation results indicate that the uneven rate coefficient is 0.266 and volatility is 0.515 in the entrance of closed-couple catalyst.

This paper simulates air flow in inlet manifold in some engine with CFD calculation method. Results coincide well with experimental data, which indicates that turbulence in bend is the principal factor of flow loss. On the basis of spatial arrangement, the structure of inlet manifold is redesigned and optimized. Cross section of bend is designed as oblate shape and the inlet crosssection of manifold is increased while its radius is increased at the same time. Flow resistance and flow rate after optimization are superior to the prototype machine.

For the purpose of increasing applicability of combustion chamber simulation, computational domain, boundary condition, simplicity of complicated structures, mesh generation and physical parameters are investigated in this paper. An annular combustion chamber of some aero-engine is studied by means of predictive numerical simulation. The computational domain includes diffuser, swirler, inner flame tube, inner ring of combustion chamber and the flow channel of all the holes on the wall of flame tube. The film cooling holes row was simplified into a slit filled with porous media. Realizable k-turbulent model and non-premixed combustion model were adopted. Model of pressure atomization nozzle were calibrated and validated through inner nozzle flow property two-phase flow VOF model and experimental data. Physical parameters are express through polynomial functions. A commercial CFD code was adopted on a high performance computing cluster with parallel algorithm and the solving method are high-order discretization scheme. The velocity, pressure, temperature, fuel spray, density of fuel and productions, etc. are calculated and validated with the experimental data.