Non-Invasive Monitoring of the Technical Condition of Power Units Using the FAM-C and FDM-A Electrical Methods

This article presents the selected results of analytical and structural work conducted at the Air Force Institute of Technology (pl. ITWL) in the field of building a measuring apparatus for non-invasive monitoring of the technical condition of aircraft power units. Presented innovative FAM-C and FDM-A methods allow for observation of frequency modulation parameters as well as identification and diagnostic classification of particular mechanical subassemblies supplying the on-board generator and thus enable non-invasive monitoring of technical condition of the aircraft power unit and the aircraft propulsion system. The main purpose of this article is to present the measurement apparatus errors that occur in the signal conditioning system in the FAM-C and FDM-A methods. In spite of the fact that the measuring instrument was built on the basis of digital technology and that it uses typical solutions of electronic frequency measurement, due to the specificity of the applied diagnostic method there occur specific measuring errors which are presented in this article.

Fatigue failure warning method for needled ceramic matrix composite by acoustic emission monitoring

Ceramic matrix composite is a kind of mechanical engineering material with excellent high temperature mechanical properties, which has been widely used in aircraft propulsion system and thermal protection system. Therefore, it is of great significance to study the fatigue failure of needled ceramic matrix composite. In this investigation, based on the realtime acoustic emission (AE) monitoring of needled C/SiC ceramic matrix composite, the characteristics of AE energy during the fatigue damage process were obtained. In addition, considering the emission coefficient of AE energy and the threshold value of AE energy in single cycle, a method for judging the imminent fatigue failure of needled composite was proposed. By comparing the cycle of failure warning by proposed method with the experimental fatigue life, the proposed method can provide fatigue failure warning near and before fatigue failure.

Voltage synchronisation for hybrid-electric aircraft propulsion systems

Increasing demand for commercial air travel is projected to have additional environmental impact through increased emissions from fuel burn. This has necessitated the improvement of aircraft propulsion technologies and proposal of new concepts to mitigate this impact. The hybrid-electric aircraft propulsion system has been identified as a potential method to achieve this improvement. However, there are many challenges to overcome. One such challenges is the combination of electrical power sources and the best strategy to manage the power available in the propulsion system. Earlier methods reviewed did not quantify the mass and efficiency penalties incurred by each method, especially at system level. This work compares three power management approaches on the basis of feasibility, mass and efficiency. The focus is on voltage synchronisation and adaptation to the load rating. The three methods are the regulated rectification, the generator field flux variation and the buck-boost. This comparison was made using the propulsion system of the propulsive fuselage aircraft concept as the reference electrical configuration. Based on the findings, the generator field flux variation approach appeared to be the most promising, based on a balance of feasibility, mass and efficiency, for a 2.6MW system.

Wing magnetohydrodynamic facility of aircraft propulsion system

Magnetohydrodynamics is one of the relatively new fields of physics studying the dynamics of magnetic fields in electrically conductive fluids. The implementation using magnetohydrodynamic principles applied to aircraft propulsion systems is so far only in a range of experiments. So far, real applications have occurred only a few times and always only at the level of experiments and prototypes. In my paper, I deal with the application of a magnetohydrodynamic device built into the wing of an airplane. This means should work as a secondary type of drive in cooperation with the primary drive, which is represented by a turbofan motor. The device´s main function is to reduce the fuel requirements of the primary drive and reduce noise and other harmful emissions. The work also includes drawings created in the program AutoCAD, where I designed the location and implementation of a wing magnetohydrodynamic device in the wing of general construction. In this work, I also explore the advantages and disadvantages of using different tips of the primary drive. I am also researching the current state of the problem where I am analyzing the Japanese project of the YAMATO-1 semi-catamaran with magnetohydronymous propulsion and a prototype of an ion-powered crawler from IMT scientists. I also examine in detail all the theoretical knowledge concerning magnetohydrodynamics and wing design. Finally, I compare the advantages and disadvantages of using this tool as well as other technical issues related to construction. This work can serve as a basis for further future research into the application of magnetohydrodynamic principles in aviation

Multi-Agent Fuzzy Logic Controller applied to One Lever Variable Pitch Turboprop Aircraft

Modern aircraft turboprop engines are generally managed by pilots by using the well-established two-levers approach which allows the pilot to control independently the engine thrust (power lever) and the propeller rotational speed (condition lever). On the other hand, the twolevers governing system presents several disadvantages in terms of pilot training, fuel consumption and aircraft maintenance. The one-lever approach tries to solve such drawbacks regulating at the same time the engine power and the propeller pitch. In the present work a Multi-Agent Fuzzy Logic control algorithm has been proposed to implement the one-lever approach for the control of the variable pitch turboprop aircraft propulsion system. The whole aircraft ecosystem has been developed in Simulink® framework to verify the feasibility and performance of the proposed one-lever approach.

A Study of Two Variable Cycle Engine Concepts for High Speed Civil Aircraft

High speed civil aircraft has become a promising field with the development of globalization. The propulsion system is an indispensable part of the aircraft. Conventional engines have difficulty meeting the performance requirement of the high-speed civil aircraft. In this article, two variable cycle engines were studied to preliminarily as aircraft propulsion system. Their performance and matching mechanism were analyzed and compared with each other. Firstly, the cycle parameters design was conducted to explain the principle of cycle parameter determination for the high-speed civil aircraft. Secondly, the control law of variable geometry components was studied to optimize engine performance during supersonic cruising. Finally, the throttling process with constant airflow was studied to solve the problem of thrust surplus during subsonic cruising. According to this study, given same cycle parameters, the engine with variable fan stage can produce equal or slightly higher thrust with slightly less fuel consumption than the engine with core-driven-fan stage. The engine with core-driven-fan stage has advantages in aero-dynamical stabilities. It can also throttle to slightly lower thrust level during subsonic cruising. Considering the advantages in performance and derived development comprehensively, the engine with variable fan stage is a better option for high speed civil aircraft.