Analysis And Prediction Of Frost For Aircraft On The Ground

The frost formation of aircraft on the ground has a negative impact on the flight performance and effect the aircraft de-icing efficiency. The environment of frost formation is complex that exist so many uncertain factors and the frost growth is still unknown at present.In order to ensure the safety of flight and airport operation efficiency, it is necessary to accurately analysis and prediction the conditions of aircraft frosting on the ground. In this paper, taking these problems as the target to study systematic theoretical analyses and experimental research for the frost formation of aircraft on the ground, a variety of forecasting methods have been provided to predict the frost formation. The main contents are as follows:Based on the mechanism of the frost formation to derivation the frost balance equations of heat and mass transfer on aircraft wing surface.This paper proposes a new frost crystal tree model to describe the growth and structure of frost layer, the formation of frost layer model has been established in order to analyze the parameters to understand the curve features of this model. The simulation system for aircraft's frost formation environment on the ground has been established. Analyze the data from experiments which have different temperatures,different relative humidity and different volume of water molecules to study the environmental factors that affect the aircraft frost growth. The parameters of the growth model has been calculated such as average coefficient of thermal conductivity and density under different environmental conditions from simulation frosting experiments to increase understanding the change of growth curves and growth rates.A new kind of nested polynomial prediction model to solve the short-term prediction problem under different simulation environment for aircraft frost formation on the ground has been put forward. Due to the limitation of the polynomial prediction and extensibility is poor,a new model is proposed which piecewise polynomial combine with growth model to predict the frost on different times to improve the precision of prediction. Based on the principle of grey prediction to establish three grey prediction models for aircraft frost formation :OSFDGM(1,1) model, DGM(1,3) model and grey combination model. Compared with polynomial combination model, analyses the applicability and precision of these prediction models in different indoor simulation environments of the aircraft's frost formation on the ground. Based on the real outdoor frost formation situation puts forward a piecewise-combination forecast model, compared with grey combination forecast model,obtain the result that frost formation grey combination model prediction accuracy is higher in medium-term prediction, and the frost formation piecewise-combination forecast model accuracy is higher in long-term prediction.