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RISS 인기검색어
- 검색키워드
- 저자 : Chen ShiChun (검색결과 4 건)
- 무료
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- 유료
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Grinding Marks on Ultra-Precision Grinding Spherical and Aspheric Surfaces
Bing Chen,Bing Guo,Shichun Li,Zhaohui Deng,Qingliang Zhao 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.4 No.4
Grinding marks are regard as a great obstacle to manufacture spherical and aspheric surfaces with higher surface quality, lower energy and wastage. The scallop-height was studied for optimizing the grinding parameters firstly to reduce its effect on grinding marks. Secondly, the expression of grinding points distribution was established to characterize the grinding marks caused by the radial run-out of grinding wheel. And then, the aspheric grinding experiments of monocrystalline silicon were carried out to investigate the influence of grinding marks on surface quality. The experiments revealed that the remarkable grinding marks with patterned grinding points distribution would cause more fractures and roughness, deeper grooves, and more inhomogeneous surface quality compared with the weak grinding marks. The discriminating standard of grinding marks was established, and the grinding parameters were optimized for homogenizing the grinding points distribution by this discriminating standard to reduce the grinding marks in actual grinding process. Finally, the large size infrared lens was ground with high surface quality by the optimized grinding parameters, and the results of surface quality demonstrate that the discriminating standard was effective. This research provides references and ideas for grinding aspherical surface with high surface quality and efficiency, low energy and wastage.
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Simulation of Conceptual Designs of a Three-Surface Stealth Strike Fighter
Kuizhi, Yue,ShiChun, Chen,Wenlin, Liu,Dazhao, Yu The Korean Society for Aeronautical and Space Scie 2014 International Journal of Aeronautical and Space Sc Vol.15 No.4
A conceptual design of a three-surface strike fighter was studied and stealth performance was taken into account to enhance survivability and battle effectiveness. CATIA was used to design the aircraft's three-dimensional prototype model and the weapon carriage arrangement was also studied. The aircraft's RCS characteristics and distributions under X, S, C, and L bands were simulated using the RCSPlus software, which is based on the PO method. Pressure and velocity distributions of the flow field were also simulated using CFD. A turbulence model was based on standard $k-{\varepsilon}$ function and N-S functions were used during the CFD computation. Lift coefficients, drag coefficients, and lift-to-drag ratio were obtained by aerodynamic simulation. The results showed that: (1) the average value of head-on RCS between ${\pm}30^{\circ}$ is below -3.197 dBsm, and (2) the lift coefficient is 0.34674, the drag coefficient is 0.04275, and the lift-to-drag ratio is 8.11087 when the attack angle is $2.5^{\circ}$.
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Simulation of Conceptual Designs of a Three-Surface Stealth Strike Fighter
Yue Kuizhi,Chen ShiChun,Liu Wenlin,Yu Dazhao 한국항공우주학회 2014 International Journal of Aeronautical and Space Sc Vol.15 No.4
A conceptual design of a three-surface strike fighter was studied and stealth performance was taken into account to enhance survivability and battle effectiveness. CATIA was used to design the aircraft’s three-dimensional prototype model and the weapon carriage arrangement was also studied. The aircraft’s RCS characteristics and distributions under X, S, C, and L bands were simulated using the RCSPlus software, which is based on the PO method. Pressure and velocity distributions of the flow field were also simulated using CFD. A turbulence model was based on standard k-ε function and N-S functions were used during the CFD computation. Lift coefficients, drag coefficients, and lift-to-drag ratio were obtained by aerodynamic simulation. The results showed that: (1) the average value of head-on RCS between ±30° is below -3.197 ㏈sm, and (2) the lift coefficient is 0.34674, the drag coefficient is 0.04275, and the lift-to-drag ratio is 8.11087 when the attack angle is 2.5°.
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Wind tunnel tests and CFD simulations for snow redistribution on 3D stepped flat roofs
Zhixiang Yu,Fu Zhu,Ruizhou Cao,Xiaoxiao Chen,Lei Zhao,Shichun Zhao 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.28 No.1
The accurate prediction of snow distributions under the wind action on roofs plays an important role in designing structures in civil engineering in regions with heavy snowfall. Affected by some factors such as building shapes, sizes and layouts, the snow drifting on roofs shows more three-dimensional characteristics. Thus, the research on three-dimensional snow distribution is needed. Firstly, four groups of stepped flat roofs are designed, of which the width-height ratio is 3, 4, 5 and 6. Silica sand with average radius of 0.1 mm is used to model the snow particles and then the wind tunnel test of snow drifting on stepped flat roofs is carried out. 3D scanning is used to obtain the snow distribution after the test is finished and the mean mass transport rate is calculated. Next, the wind velocity and duration is determined for numerical simulations based on similarity criteria. The adaptive-mesh method based on radial basis function (RBF) interpolation is used to simulate the dynamic change of snow phase boundary on lower roofs and then a time-marching analysis of steady snow drifting is conducted. The overall trend of numerical results are generally consistent with the wind tunnel tests and field measurements, which validate the accuracy of the numerical simulation. The combination between the wind tunnel test and CFD simulation for three-dimensional typical roofs can provide certain reference to the prediction of the distribution of snow loads on typical roofs.
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