Multidimensional discrete gust loads of a large civil flexible aircraft

摘要

An alternative to the conventional Isolated Discrete Gust model for critical loads assessment is formulated in this research. The formulation of the multidimensional discrete gust model is inspired by DARPA recommendations, originally suited for large scale unmanned vehicles. Motivation to add a spanwise variation to gust profiles for loads alleviation of large flexible aircraft can be found in the desire for higher span and aspect ratio wings that exhibit larger flexibility effects. The CA~2LM framework used for this research is presented along with modifications made to the discrete gust definition capability. Nonuniform spanwise variation in gust intensity is allowed using sinusoidal user defined functions for gradients and amplitude. Structural loads and flight dynamic results are provided for both symmetric and asymmetric gust encounters. A comparison between the conventional and multidimensional gust definition is made for multiple case to generate a wide spectrum of gradients at multiple flight conditions for a representative large aircraft. A discussion is also presented regarding the relevance of the incorporated gust intensity tuning method based on gradient lengths.