Journal of Aerospace Engineering

In order to study the vibration transfer characteristics of a dual-rotor aeroengine system, an aeroengine system dynamic model containing high- and low-pressure rotors as well as inner and outer casings is established. The Newmark-$\beta$ method is used to solve the developed model and obtain the dynamic characteristics of the system. This paper proposes a dynamic model and operational transfer path analysis (OTPA) method to analyze the vibration transfer path of a dual-rotor aeroengine system. The concept of insertion loss is introduced, and Cramer’s rule is used to improve the computational efficiency of dynamic equations for systems with variable stiffness and damping matrices. The vibration contribution of three vibration transfer paths is calculated separately. A dual-rotor–casing vibration transfer path test bench is built to make experimental research on vibration transfer characteristics and verify the accuracy of simulation results. The results indicated that among the three vibration transfer paths, the first vibration transfer path has the highest contribution to the vibration of the outer casing of the system. Due to the nonlinear superposition of responses, the overall response amplitude of the outer casing shows an increasing trend as the rotational speed ratio increases. The contribution rate of the three paths does not change with the rotational speed, and the vibration contribution of each path at different rotational speed ratios fluctuates slightly near the mean.

Air data inertial reference system (ADIRS) parameters are very important for the safe flight of an aircraft. The ADIRS consists of air data inertial reference units (ADIRUs) and the air data reference (ADR) part of the ADIRU, which provides the air data [altitude (ALT), angle of attack (AOA), airspeed, and temperature information] examined in this study. ADR is essential to continuously ensure accurate and precise information to the flight management guidance computers (FMGCs), electronic flight instruments system (EFIS), and other systems on the aircraft for reliable and safe flight operation. This study estimated the ADR parameters (altitude, angle of attack, airspeed, and temperature) to obtain a synthetic air data system for data continuity in the event of any sensor failure on the aircraft using correlated data. According to correlation analysis, the angle of attack, computed airspeed (CAS), and static air temperature (SAT) data have the highest correlation with the stabilizer position (STAB), whereas the altitude data have the highest correlation with the low-pressure engine spool rotational speed (N1). The AOA, CAS, SAT, and ALT parameters were estimated by decision tree, support vector machine, and Gaussian process regression models using real flight data collected from a local airline. The Gaussian process regression model was better at generalizing the data set for data estimation than were the other machine learning methods used in this study. MATLAB version R2023a software was used in all operations.

To more accurately characterize the load characteristics of birds under the impact of aviation structures, this study conducted computed tomography scanning of a 1-kg chicken and proposed a geometric model of the bird, including bones, muscles, viscera, and cavities. The constitutive model of fluid dynamics was used to describe the rheological properties of muscle viscera, and a bilinear follow-up plastic model with failure was proposed to describe the mechanical behavior of bones under high-speed impact, and then the bone and muscle/viscera models were assembled into a refined bird model to establish a finite element model. The model was verified with bird impact testing on a rigid target. By comparing and analyzing the impact pressure with the traditional bird model, it was found that the initial impact pressure and stagnation flow pressure of the CT scan refined bird model were lower than those of the traditional bird model and were close to the experimental values. The reason for this phenomenon is that the CT scan refined bird model to some extent reproduces the response of the real structure inside the bird body during the impact process, the high strength level of the bone part model will reduce the material’s movement speed after the bird body model rheological changes, and it well demonstrates the phenomenon of reduced mixing density after rheological deformation during simulation.