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Technical Paper

Cycle Variation Analysis of Initial Flame Propagation Process in a Model Engine

2004-10-25
2004-01-3007
Instability of the Initial flame propagation is examined after computing the flows during three continuous cycles of an engine. Cycle-resolved large eddy simulation (CLES) is employed for these computations. First, we calculated the compressible turbulent flows during three continuous cycles in a model engine having square piston. Then, the initial flame propagation processes are calculated by using G-equation at the flow condition of TDC. Grid system of 1,000,000 points is employed. Relation between cyclic-resolved turbulence and initial flame is qualitatively examined by the computational results.
Technical Paper

Cycle-resolved Computations of Compressible Flow in Engine

2002-10-21
2002-01-2694
Turbulent flows in a model engine having a square piston were analyzed in detail by using a numerical simulation method with higher-order accuracy to perform simulations on an orthogonal homogeneous grid without grid motions. Calculations were performed during several continuous engine cycles. A better understanding of the cycle-by-cycle differences, i.e., cyclic variations, in flow fields may lead to more effective ways of stabilizing combustion.
Technical Paper

Large Eddy Simulation of Premixed-Flame in Engine based on the Multi-Level Formulation and the Renormalization Group Theory

1992-02-01
920590
Large Eddy Simulation of the turbulent premixed-flame in engine is performed in a wide range of the operating conditions such as engine speed, air-fuel ratio, and ignition timing. Firstly, a mathematical formulation suitable for Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) of the compressible turbulence and combusting flows is derived, which is the Multi-Level formulation. And a numerical algorithm based on the formulation is developed in order to calculate precisely the supergrid fluctuations of the physical quantities. As the determinations of the subgrid-turbulence and flame wrinkling, the Yakhot-Orszag turbulence model based on the Renormalization Group theory(RNG theory) and a flame-sheet model are combined with the numerical code. Computations are performed for a real engine with dual intakeport and valves. Obtained computational data agrees well with the experimental data on turbulence-intensity and pressure history.
Technical Paper

Numerical Simulation of the Detailed Flow in Engine Ports and Cylinders

1990-02-01
900256
Computation of the three-dimensional flow in the intake ports and the cylinders of real engines, including moving valves and piston, has been carried out by solving the Navier-Stokes equations. No explicit turbulence models are used. An extended version of the SIMPLE and ICE method is employed to simulate density variations in engines, which are connected with compression rate, heat transfer, and compressibility. A third-order upwind scheme is combined with this method. Computational results show complex flow fields such as separated flows near the valve seat and small vortices of the order of the mesh size near the end of compression. These computational results are compared with the LDV measurements.
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