The Use of Variable Fidelity Models in the Optimization Problems for Aircraft Engines Parameters and Control Laws

Abstract

The typical situation when solving a problem of an aircraft engine optimization is that a researcher has several tools for effectiveness indices analysis, distinguished according to the levels of complexity and accuracy. The high-fidelity tools can be the detailed nonlinear mathematical models or even the experimental samples of the engine or its components. However the implementation of optimization researches using such a tools is associated with the significant time expenditures. The low-fidelity models also allow us to carry out optimization search, but the validity of the obtained results can be rather low. Therefore the methods based on a combination of various levels of the analysis tools are going to be used in the field of optimization of the aircraft engines parameters and control laws. The given paper introduces the multicriteria optimization procedure for aircraft power plants and their components. The procedure is based upon the adaptive use of different levels analysis tools. The proposed approach is intended to minimize the complicated analysis tools application. It uses the method of indirect optimization on the base of self-organization, which permits to find numerically the Pareto-optimal set of solutions, uniformly distributed in the criteria space. The effectiveness of the proposed optimization procedure is demonstrated by two examples. The first one is a problem to find the optimal control laws for the power plant of short take-off and vertical landing aircraft for its take-off (50 variables, 2 criteria). The second one is the problem of multistage axial compressor optimization aimed at its efficiency maximization (42 variables, 2 criteria).