Search results

Wingtip loss is an existing type of transport aircraft hazard which is a real threat to flight safety caused by a missile strike, underwing engine explosion or impact with obstructions when performing near-ground operations. The primary effect of the wingtip loss is an asymmetric rolling moment, which may result in the fatal loss of control for the aircraft. This study aims to assess whether aerodynamic degradation will cause a wing-damaged transport aircraft to lose its balance under a certain level of wing damage and if a pilot can compensate for the loss of aerodynamic force and regain the balance of the aircraft.

In this paper, experimental and numerical studies were conducted to investigate the aerodynamic characteristics of a wingtip-lost transport aircraft in landing configuration. Various levels of wing damages including wingtip, slat and flap loss were considered. The numerical simulations were performed with ANSYS Fluent. The computational fluid dynamics calculation was validated by wind tunnel tests.

The aerodynamic performance of the aircraft with wing-damaged condition was presented. It was revealed that the wingtip loss leads to an asymmetric rolling moment and a reduction of the lift force, which affects the balance of the transport aircraft. The methods to compensate for the lift force and the asymmetric rolling moment were investigated for a safe landing. The lateral balance cannot be maintained in cases with serious damage on the wing (larger than 53% of the semi-span) or moderate damage on the wing with loss of slats and flaps.

The nonlinear results indicate the importance of aerodynamic assessment for the sake of training pilots to properly handle the hazard situation and explore the critical facts leading to the air crash.

To understand the service performance of full ceramic ball bearings under extreme working conditions and improve their service life, dynamic characteristic tests of full ceramic ball bearings under ultra-low temperature conditions were carried out by a low-temperature bearing life testing machine, and temperature rise and friction were measured under extreme low-temperature environment.

The heat-flow coupling model of bearing was established by CFD software, and the test results were further analyzed.

The results show that the temperature rise of the bearing is not obvious in the liquid nitrogen environment. With the increase of the chamber temperature, the lubrication state of the bearing changes, resulting in the temperature rise of the outer ring of the bearing. As the temperature of the test chamber increases, the friction force on the bearing increases first and then decreases under the action of multifactor coupling.

The research results provide test data and theoretical basis for the application of all-ceramic ball bearings in aerospace and other fields and have important significance for improving the service life of high-end equipment under extreme working conditions.

The research results provide test data and theoretical basis for the application of full ceramic ball bearings in aerospace and other fields and have important significance for improving the service life of high-end equipment under extreme working conditions.

The research results provide test data and theoretical basis for the application of full ceramic ball bearings in aerospace and other fields and have important significance for improving the service life of high-end equipment under extreme working conditions.

The research results provide test data and theoretical basis for the application of full ceramic ball bearings in aerospace and other fields and have important significance for improving the service life of high-end equipment under extreme working conditions.