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Time-averaged temperatures at critical locations on the piston of a direct-fuel injected, two-stroke, 388 cm3, research engine were measured using an infrared telemetry device. The piston temperatures were compared to data [7] of a carbureted version of the two-stroke engine, that was operated at comparable conditions. All temperatures were obtained at wide open throttle, and varying engine speeds (2000-4500 rpm, at 500 rpm intervals). The temperatures were measured in a configuration that allowed for axial heat flux to be determined through the piston. The heat flux was compared to carbureted data [8] obtained using measured piston temperatures as boundary conditions for a computer model, and solving for the heat flux. The direct-fuel-injected piston temperatures and heat fluxes were significantly higher than the carbureted piston. On the exhaust side of the piston, the direct-fuel injected piston temperatures ranged from 33-73 °C higher than the conventional carbureted piston.

A computational investigation of the effects of activation energy, porosity, and pore size on the gasification of combustion chamber deposits in spark ignition engines has been performed. The oxygen in the combustion gases reacts with the carbonaceous deposit and causes the deposit to burn away. Experimentally measured deposit parameters such as heating value, surface temperature, surface pressure and porosity were used in the model. Several models for predicting the gasification of the deposit were investigated. A random pore intersection model developed by Petersen was used to predict the gasification of the deposit. The chemical reactions were modeled with a simple Arrhenius expression. The flow within the deposit was modeled using Darcy's Law. The Kozeny-Carmen equation was used to relate deposit permeability and porosity. The model was incorporated into a finite difference code that predicts the heat transfer and fluid flow through the deposit.