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Application of the engine CFD code KIVA II with the inclusion of the SHELL model for autoignition chemistry, and the discrete transfer radiation heat transfer model, has enabled the technically important problem of non luminous radiation from the major emitting species CO2 and H2O in the combustion products within the cylinder of a spark ignition engine to be considered as a combustion diagnostic aid, and also as a method of controlling individual cylinder Air/Fuel ratio. Results from a parametric study using CFD have been found to corroborate the experimental findings of other workers over a range of operating conditions including knock.

Combustion noise produced by the direct injection Diesel engine is a consequence of the dynamic equilibration of the high local pressures created in the combustion space following autoignition that stimulates the resonance modes, over a range of frequencies, of the gas contents of the engine cylinder. In this paper Computational Fluid Dynamics has been used to study the effects of changes in engine design and operating parameters that, from empirical experience, are known to influence the noise output of an engine, and explanations confirmed or given for well-established behaviour.

The CFD code KIVA has been applied to the simulation of the transient air-assisted fuel injection(AAFI) process, in which air and fuel at moderate pressures are mixed in an interior chamber of the injector before passing through a pintle valve into air at near ambient pressure in a cylinder. On passage through the pintle valve fuel is atomised. Because of the small dimensions of the flow passages within the injector, a very fine computational grid structure is used to accurately resolve the flow behaviour. Adopting an axisymmetric grid structure enables symmetry to be exploited. The computational results are validated with experimental data for fuel jet penetration and spread with time, obtained using Schlieren visualisation. The simulation of air blast atomisation in an engine cannot utilise the fine grid structure above because of the large computational resources required.

The Computational Fluid Dynamics (CFD) code KIVA II has been applied to simulate the in-cylinder mean air motion (tumble) and turbulence levels in a motored 4-stroke single cylinder engine with pentroof combustion chamber geometry, having two inlet and two exhaust valves. In-cylinder flow during intake and compression strokes were simulated and a comparison between computational and experimental results were made. The mean turbulent kinetic energy and tumble ratio variation during the compression stroke obtained with CFD, have been compared with computational and experimental data from published literature. The simulation shows general similarity of flow structure and magnitude with published data on engines with similar geometry and initial flow conditions in the cylinder.

The Computational Fluid Dynamics (CFD) Code KIVA II has been applied to model combustion pressure oscillations in the Indirect Injection Diesel Engine. These oscillations are attenuated and transmitted by the engine structure to the surroundings as noise. The computational model was used to evaluate changes in design and operating characteristics of an engine, and the effect of these on the intensity of gas pressure oscillation. The results in general corroborate the trends of published experimental measurements of combustion noise. A 40% increase in grid resolution showed minor changes in the magnitude of cylinder pressure oscillation and approximately 0.5ø crank angle phase advance in the oscillation cycle compared with the grid used for the results presented here.

In this paper the effect of in-cylinder crevices formed by the piston cylinder clearance, above the first ring, and the spark plug cavity, on the entrapment of unburned fuel air mixture during the late compression, expansion and exhaust phases of a spark ignition engine cycle, have been simulated using the Computational Fluid Dynamic (CFD) code KIVA II. Two methods of fuelling the engine have been considered, the first involving the carburetion of a homogeneous fuel air mixture, and the second an attempt to simulate the effects of manifold injection of fuel droplets into the cylinder. The simulation is operative over the whole four stroke engine cycle, and shows the efflux of trapped hydrocarbon from crevices during the late expansion and exhaust phases of the engine cycle.

The process of autoignition in an internal combustion engine cylinder produces large amplitude high frequency gas pressure waves accompanied by significant increases in gas temperature and velocity, and as a consequence large convective heat fluxes to piston and cylinder surfaces. Extended exposure of these surfaces to autoignition, results in their damage through thermal fatigue, particularly in regions where small clearances between the piston and cylinder or cylinder head, lie in the path of the oscillatory gas pressure waves. The ability to predict spatial and temporal' variations in cylinder gas pressure, temperature and velocity during autoignition and hence obtain reasonable estimates of surface heat flux, makes it possible to assess levels of surface fatigue at critical zones of the piston and cylinder head, and hence improve their tolerance to autoignition.

Transputer based concurrent processing has been applied to an extensive engine based Camputational Fluid Dynamics Code - KIVA, and demonstrated to be effective in terms of accuracy and cost. Scope exists for further adaptation of the code to the hardware to enhance performance. The use of concurrent processing with Transputer hardware merits consideration as a powerful and inexpensive engineering computational aid.