Validation and Uncertainty Quantification of an Ethanol Spray Evaporation Model

The need for alternative fuels brings news challenges for the transportation industry. Especially for aviation no near- or mid-term alternatives to combustion engine exist. The introduction of new fuels challenges existing systems and might require the development of fuel flexible engines in the long-term. To ensure operational safety a detailed understanding of fuel effects on combustion processes is crucial. Numerical simulation might a very beneficial tool to investigate fuels effects and to design new combustion chambers. But especially in aviation risk-informed decision-making is a must. In this study the focus is on the validation of fuel evaporation models. Evaporation, as an important process in the fuel preparation process, can have a remarkable influence on precedent combustion processes. Previous validations of evaporation models are mainly based on experiments with suspended droplets. While this technique is beneficial for a first qualitative characterization, it is well known that the suspension modifies the behavior of the droplets. Furthermore uncertainties of the required model inputs have not yet been investigated systematically to the best of the authors' knowledge. In this study the validation metric for ethanol spray evaporation will be constructed. Experiments have been performed in a system built to study the evaporation of different fuels sprays for the evaluation of accuracy of fuel evaporation models. The paper explores specifically the problems faced in multiphase flow validation activities. The strategies involved e.g. for parameter estimation, input uncertainties quantification and their effect on simulation output precision will be discussed in detail.