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NAA
Beijing, China

He S.,NAA | Liu D.,NAA | Tan D.L.P.,NAA
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2015

A method to build preliminary wind over deck envelope of aircraft landing and launching aboard battle ship was proposed. Similarity rules and some considerations during results comparison among CFD simulation, wind tunnel test and full-scale test at sea were given. Take a battle ship for an example, ship bow anemometer disposition, histogram of relative wind velocity measured by the bow ship anemometer, histogram of the wind velocity of one concerned point in the airfield, comparison of non-dimensional wind velocities as a function of relative wind angle, regression analysis of wind velocity data, and comparison of turbulence intensity were performed. The preliminary wind over deck envelope proposed could be a guidance to flight test at sea, and quicken the generation of formal WOD envelope. ©, 2015, Wuhan University of Technology. All right reserved. Source


Zhang L.-J.,Shanghai JiaoTong University | Zhang L.-J.,Wuhan University | Wang D.-Y.,Shanghai JiaoTong University | Zhu X.,Wuhan University | Zhang L.-J.,NAA
Chuan Bo Li Xue/Journal of Ship Mechanics | Year: 2010

The frequency selective surface (FSS) is applied widely. In many circumstances, the FSS is subjected to all kinds of forces, such as the FSS embedded in the shell of integrated mast and microwave absorber structure. In this paper, a research is conducted to find out whether and how the electromagnetic property of FSS changes when the FSS is subjected to force. Firstly, an analysis is conducted on the mechanism of the influence of force on the electromagnetic property of FSS. Then, by using both mechanics finite element method and electromagnetics finite element method, an investigation is conducted to find out the pattern and magnitude of the change of FSS's EM property caused by forces various in direction and magnitude. The curve of EM property-force gotten shows: the change mainly lies in the excursion of the resonant frequency and the altering of the bandwidth; the sensitivity of EM property to the force alters greatly when the direction of force changes. In order to depress the influence of the force on the EM property, the disposal of the FSS should ensure the direction, in which the forces are loaded, to avoid the ones which may make greater influence occur; the FSS with round-cornered aperture is needed to be researched. Source


He S.-H.,NAA | Liu D.-Y.,NAA | Tan D.-L.,NAA
Applied Mechanics and Materials | Year: 2014

For numerical simulation of ship airwake by CFD, based on the use of an unstructured grid, the k-ε turbulence model and SIMPLE algorithm, the characteristic features of complex fluid flows eg recirculation zones and strong vortex fields in the aircarft operating region of a generic 3D frigate model was presented. The accuracy of the predication was checked by performing calculations on different grid sizes and comparing with wind-tunnel flow visualization data. A comparison of several typical spatial discretization schemes was performed. y+ values were also tested. The general features of the flow predicted in this paper compare reasonably well with experimental data. However, CFD simulation produced a higher velocity in the vicinity of vortex zone when compared to experimental data. Obvious differences exist between results by first-order upwind scheme (power law scheme) and second-order upwind scheme (QUICK scheme, third-order MUSCL scheme). Second-order upwind scheme (QUICK scheme, third-order MUSCL scheme) are recommended for the CFD simulation of ship airwakes with a modest increase in computational cost. y+ values from o(10) to o(1000) can all be accepted for the CFD simulation of ships(e.g., SFS1) with Reynolds number 108 or more. © 2014 Trans Tech Publications, Switzerland. Source


He S.,NAA | Liu D.,NAA | Fang S.,Office for Importing Equipment of the South China Sea Fleet | Tan D.,NAA | Liu P.,NAA
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2015

For rapid predication of characteristics of ship air flow fields by CFD, Reynolds number independence, unviscous assumption, steady computation replacing time-accurate simulation were proposed. It was also emphasized that discretization schemes, turbulence models, flow algorithms are some factors not to be ignored for rapid ship airwakes predication. The feasibility and deficiency of application of Reynolds number independence, unviscous assumption, and steady computation replacing time-accurate simulation on ship airwakes predication were studied through a generic 3D frigate model. Part of the simulation results were checked by experimental data. The results of these studies show that, based on the Reynolds independence, only one solution need be run for each wind angle of interest. Based on unviscous assumption, the computational speed of ship airwakes could improve up to 30%, and less the word load of meshing. Replacing the time-accurate simulation with steady simulation, the cost of time could be reduced substantially, however, the steady simulation can only be accepted for qualitative characteristics of ship air flow fields. On the premise of high orthogonal quality of mesh, computational efficiency could be improved by employing lower order discretization schemes when compared to higher order discretization schemes, and the accuracy can keep at a same level. RANS turbulence model, SIMPLER and PISO flow algorithms were prior to others for a higher computational speed in CFD simulation of ship airwakes. ©, 2015, Wuhan University of Technology. All right reserved. Source

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