МЕТОД ВИБОРУ СКЛАДУ І РЕЖИМУ РОБОТИ СИЛОВОЇ УСТАНОВКИ, РЕЖИМУ РОБОТИ ДЛЯ ЛІТАЛЬНОГО АПАРАТА З НАДЗВУКОВОЮ КРЕЙСЕРСЬКОЮ ШВИДКІСТЮ

Abstract

The power plant (PP) of a supersonic aircraft is a system that is part of a more complex system - the aircraft. Therefore, the efficiency of the aircraft significantly depends on the PP composition and its operating mode. Choice of composition and operation mode of PP is a part of the complex integrated variational optimization task, where parameters of flight profile, aircraft and PP are varied. Due to the complexity of the task in complete formulation, it is usually simplified. Typically, for the supersonic aircraft, the flight profile, flight mode for the cruising segment, payload, geometric shape and aerodynamic coefficients of the aircraft are specified. The dimensions and weight of the aircraft, as well as the parameters of the PP are varied. The required fuel and PP mass are determined. The minimum takeoff gross weight of the aircraft is a criterion of choosing the composition of the PP. A main disadvantage of this method is the insufficiently successful decomposition of the complex problem. In particular, the issues of aircraft aerodynamics, aircraft design and the theory of air-breathing engines are being comprehensively resolved, which complicates the task both in scientific and organizational terms - it is difficult to set design tasks for specialized organizations. Another decomposition method based on decomposing a complex problem into its components is proposed. The first component is the problem of choosing the composition and parameters of the PP, for the flight profile, mass, geometric and aerodynamic characteristics of the aircraft which are set; the second one is the problem of choosing the parameters of the aircraft, for the flight profile and the geometric shape of the aircraft that are set by varying the size and mass of the aircraft; the third one is the problem of choosing the parameters and geometric shape of the aircraft for the flight profile which is given by varying the geometric shape of the aircraft and the associated aerodynamic characteristics of the aircraft; the fourth one is the problem of choosing the parameters of the flight profile. Moreover, the first task is an integral part of the second one, the second one is an integral part of the third, and the third one is an integral part of the fourth. Thus, the composition of these tasks allows solving the complex problem of choosing the parameters of the flight profile, aircraft and its PP.Another disadvantage of the applied methods is the choice of a single solution based on one criterion. In practice, the choice of the solution depends on many factors; therefore, it is advisable to have a number of solutions that slightly differ in the chosen criterion, but have different vectors of flight, aircraft and PP parameters. A method of selecting the composition and parameters of the PP according to the one criterion, which ensures the receipt of a number of vectors of the PP parameters with the aim of the subsequent selection of the parameter vector that satisfies a number of criteria is proposed in the article. In addition, the use of a complete mathematical model which is used the differential equations of aircraft motion in the optimization task requires large computing resources. A more rational method is a rough search for a solution using a simplified model, followed by a correction of the solution result using a complete model ("predictor-corrector" type methods). The method of choosing parameters using the "predictor - corrector" scheme is proposed in the article. The predictor is a simplified model based on the use of the cruising flight segment for the selection of aircraft and PP parameters. The corrector is the complete model using the differential equations of aircraft motion and fuel consumption, applied to all segments of the aircraft flight profile.The developed method provides obtaining a number of PP parameter vectors that are best according to the given efficiency criterion, which makes it possible to make a subsequent choice of the PP parameters vector taking into account all efficiency criteria.