Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
Time is crucial in the airlines industry. Among all factors contributing to an aircraft\nturnaround time; passenger boarding delays is the most challenging one. Airlines do not have\ncontrol over the behavior of passengers; thus, focusing their effort on reducing passenger\nboarding time through implementing efficient boarding strategies. In this work, we attempt to\nuse cellular Discrete-Event System Specification (Cell-DEVS) modeling and simulation to provide a\ncomprehensive evaluation of aircraft boarding strategies. We have developed a simulation benchmark\nconsisting of eight boarding strategies including Back-to-Front; Window Middle Aisle; Random;\nZone Rotate; Reverse Pyramid; Optimal; Optimal Practical; and Efficient. Our simulation models are\nscalable and adaptive; providing a powerful analysis apparatus for investigating any existing or yet\nto be discovered boarding strategy. We explain the details of our models and present the results both\nvisually and numerically to evaluate the eight implemented boarding strategies. We also compare our\nresults with other studies that have used different modeling techniques; reporting nearly identical\nperformance results. The simulations revealed thatWindow Middle Aisle provides the least boarding\ndelay; with a small fraction of time difference compared to the optimal strategy. The results of this\nwork could highly benefit the commercial airlines industry by optimizing and reducing passenger\nboarding delays....
In past several decades, vortex-structure interaction generated aerodynamic noise became one of the main concerns in aircraft\ndesign. In order to understand the mechanism, the acoustic analogy method combined with the RANS-based nonlinear acoustics\nsolver (NLAS) is investigated. The numerical method is firstly evaluated by the experiment data of the classic rod-airfoil model.\nCompared with the traditional analogy methods, the RANS/NLAS can capture the nonlinear aerodynamic noise more accurately\nwith lower gird requirements. Then different rod-airfoil configurations were simulated to investigate the aeroacoustic interaction\neffects. The numerical results are in good agreement with those of the earlier experimental research. It is found that the vortexshedding\ncrash to the airfoil is the main reason for the noise generation which is dependent on the configurations, distance, and\nflow conditions....
The main structure of the composite powered unmanned airship is consists\nof airbags and four-rotor system, which airbag increases the available lift, and has\nmore advantages in terms of load and flight when compared with the traditional fourrotor\n.In order to compare the aerodynamic performance of the composite powered\nunmanned airship and the traditional four-rotor, the SIMPLE algorithm and the RNG\nk-epsilon model method are be used. The energy consumption of the composite\npowered unmanned airship is lesser than the traditional four-rotor under the same load\nand range was found....
An experimental study has been performed on water droplet deformation in the shoulder region of an airfoil. The experiments\nhave been carried out in a rotating arm facility 2.2m long and able to rotate up to 400 rpm (90 m/s). A blunt airfoil model\n(chord length equal to 0.468 m) was placed at the end of the arm. A droplet generator was used to generate a stream of water\ndroplets with an initial diameter of 1000 �¼m. An imaging system was set up to record the trajectories and deformations of the\ndroplets in three different regions close to the airfoil shoulder. The base flow field was characterized using a particle image\nvelocimetry system. The experiments show that droplet deformation results in the shoulder region of the airfoil are different\nfrom those pertaining to the leading edge region. In particular, droplets in the shoulder region tend to rotate to the direction\nof the incoming airfoil which generates an interference effect between the droplets that make up the stream. These differences\nhave been quantified applying an existing theoretical model specifically developed for the leading edge region to the results\nobtained in the present study....
In order to reduce wear and design high-performance spline coupling, the friction coefficient, wear coefficient, and wear depth of 14\ngroups of material specimens were tested using multifunctional friction and wear tester. The effect of materials, loads, rotation\nspeed, and surface treatment on friction coefficient, wear coefficient, and wear depth was investigated. A method using an\nArchard�s equation based on the finite element method to calculate the wear depth of 14 groups of material specimens was\nproposed, and the results were consistent with the experimental results. Then, the wear of a floating involute spline coupling of\naero-engine was predicted using this method. It can be concluded that carburizing and silvering can decrease the friction\ncoefficient. The wear and wear coefficient decreased after carburizing. So, it is necessary to take 18CrNi4A with carburization\nand 32Cr3MoVA with nitridation as the material of the spline coupling in aero-engine to minimize wear. Furthermore, the\nmethod presented to predicate the wear of spline coupling in this work provided a good fundament for the fatigue prediction\nmethodology of spline coupling....
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