Christian Caillol

Validation and Application of a New 0D Flame/Wall Interaction Sub Model for SI Engines

To improve the prediction of the combustion processes in spark ignition engines, a 0D flame/wall interaction submodel has been developed. A two-zones combustion model is implemented and the designed submodel for the flame/wall interaction is included. The flame/wall interaction phenomenon is conceived as a dimensionless function multiplying the burning rate equation. The submodel considers the cylinder shape and the flame surface that spreads inside the combustion chamber. The designed function represents the influence of the cylinder walls while the flame surface propagates across the cylinder. To determine the validity of the combustion model and the flame/wall interaction submodel, the system was tested using the available measurements on a 2 liter SI engine. The model was validated by comparing simulated cylinder pressure and energy release rate with measurements. A good agreement between the implemented model and the measurements was obtained.

Energy Wall Losses Estimation of a Gasoline Engine Using a Sliding Mode Observer

This paper describes an innovative method to estimate the wall losses during the compression and combustion strokes of a gasoline engine using the cylinder pressure measurement. The estimation during the compression and combustion strokes allows to better represent the system during the combustion. A sliding mode observer is derived from a validated 0-D physical engine model and its convergence and stability are proved. The observer is validated using two different engine models: a one zone engine model and a two zones engine model with flame wall interaction. A good agreement between the estimation results and the model reference is observed, showing the interest of using closed loop strategies to estimate the wall losses in a SI engine.

Heat Transfer Investigation in an Engine ExhaustType Pulsating Flow

There are many engineering practical situations where heat is transferred under conditions of pulsating flow such as in the exhaust pipes of Internal Combustion Engines. In these conditions, heat transfer mechanism is affected by the pulsating flow parameters. The objective of the present work is to experimentally investigate heat transfers for pulsatile turbulent flows in a pipe. A unique experimental apparatus able to reproduce a pulsating flow representative of the engine exhaust has been designed. A stationary turbulent hot air flow with a Reynolds number of 30000, based on the time average velocity, is excited through a pulsating mechanism and exchanges thermal energy with a steel pipe. Pulsation frequency ranges from 10 to 95 Hz. The effects of pulsation frequency and pipe length are evaluated. It has been observed that flow pulsation enhances convective heat transfers in comparison with the steady case. The test-bench architecture let us to evidence that, when the flow is excited with a pulsation frequency equal to one of the resonance modes of the system, a local maximum of the heat transfers rate appears. Such behaviour has been found to be independent of the pipe length. Results also show that the actual Nusselt correlations to predict convective heat transfer are inaccurate for pulsating flows, suggesting that new correlations which account pulsation effects have to be proposed.

A Parameter Varying Observer for the Enclosed Mass in a Spark Ignited Engine

In this paper, a high gain observer is designed for a parameter varying polytopic model to estimate the enclosed mass in the combustion chamber of a spark ignited engine. The high gain strategy allows the design of an observer that handles the uncertain part of the system. The observer uses the cylinder pressure measurement during the compression stroke to estimate the enclosed mass. An engine compression model is used as a virtual engine to build the observer. The results of the observer are compared to the virtual engine model and a good agreement between the observed variables and the model was obtained.