Vaughn College of Aeronautics and Technology

About: Vaughn College of Aeronautics and Technology is a education organization based out in New York, New York, United States. It is known for research contribution in the topics: Gravitational microlensing & Planetary system. The organization has 727 authors who have published 708 publications receiving 14082 citations. The organization is also known as: College of Aeronautics.

Study of variable stars in the MOA data base: long-period red variables in the Large Magellanic Cloud

Abstract: ABSTRA C T 146 long-period red variable stars in the Large Magellanic Cloud (LMC) from the three-year Microlensing Observations in Astrophysics (MOA) project data base were analysed. A careful periodic analysis was performed on these stars and a catalogue of their magnitudes, colours, periods and amplitudes is presented. We convert our blue and red magnitudes to K-band values using 19 oxygen-rich stars. A group of red short-period stars separated from the Mira sequence has been found on a (log P,K) diagram. They are located at the short period side of the Mira sequence consistent with the work of Wood & Sebo. There are two interpretations for such stars; a difference in pulsation mode or a difference in chemical composition. We investigated the properties of these stars together with their colour, amplitude and periodicity. We conclude that they have small amplitudes and less regular variability. They are likely to be higher-mode pulsators. A large scatter has also been found on the longperiod side of the (log P,K) diagram. This is possibly a systematic spread given that the blue band of our photometric system covers both standard B and V bands and affects carbon-rich stars.

Spiral vortex flow over a swept-back wing

Abstract: An experimental investigation has been performed to study the formation and development of spiral vortex flow over a swept-back wing. An aerofoil section with three alternative leading edge shapes was tested at sweep angles ranging from 0° to 56° for unit Reynolds numbers of 1 × 106/m and 2 × 106/m. The principal diagnostic tool was the surface oil-flow visualisation technique supplemented by pressure distribution measurements in certain cases. No spiral vortex flow was observed for sweep angles of 0° and 15° but at higher sweep angles the oil-flows indicated that there were three different mechanisms for the formation of spiral vortices. The angle of incidence at the onset of vortex flow, and the mechanism responsible for its formation, were found to depend upon the sweep angle, the leading edge shape and the Reynolds number. It was also noted that the larger the leading edge radius the greater the dependence upon Reynolds number. However, comparison with other work suggests that Reynolds number, incidence and sweep angle alone are insufficient to determine the type of spiral vortex flow occurring on a given wing.

The effect of skewing on the vorticity produced by an airjet vortex generator

Abstract: The vorticity production by a single vortex generator jet in a turbulent boundary layer at high speed and zero pressure gradient was studied by analysing surface-flow patterns. The investigation involved a range of jet mass flow rates and skew angles while the freestream Mach number and jet pitch angle were held constant. A qualitative analysis of the skin friction patterns demonstrated the effective role of the skew angle as a bifurcation parameter. The vortex production is classified into three main regimes as the skew angle increases from zero (fully downstream) to 180° (fully upstream). Better understanding of the physical mechanism behind the transition from the first regime to the second is crucial in the design of the airjet vortex generator.

Lightning Strike Ablation Damage Influence Factors Analysis of Carbon Fiber/Epoxy Composite Based on Coupled Electrical-Thermal Simulation

Abstract: According to the mathematical analysis model constructed on the basis of energy-balance relationship in lightning strike, and accompany with the simplified calculation strategy of composite resin pyrolysis degree dependent electrical conductivity, an effective three dimensional thermal-electrical coupling analysis finite element model of composite laminate suffered from lightning current was established based on ABAQUS, to elucidate the effects of lighting current waveform parameters and thermal/electrical properties of composite laminate on the extent of ablation damage. Simulated predictions agree well with the composite lightning strike directed effect experimental data, illustrating the potential accuracy of the constructed model. The analytical results revealed that extent of composite lightning strike ablation damage can be characterized by action integral validly, there exist remarkable power function relationships between action integral and visual damage area, projected damage area, maximum damage depth and damage volume of ablation damage, and enhancing the electrical conductivity and specific heat of composite, ablation damage will be descended obviously, power function relationships also exist between electrical conductivity, specific heat and ablation damage, however, the impact of thermal conductivity on the extent of ablation damage is not notable. The conclusions obtained provide some guidance for composite anti-lightning strike structure-function integration design.