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Qin W.,Harbin Institute of Technology | Pan Y.,Shanghai Institute of Spacecraft Equipment
RSC Advances | Year: 2015

Electron irradiation in outer space causes severe damage to the polymer materials of spacecrafts. An effective approach to prevent such damage is to incorporate nanoparticles into the polymeric materials. Herein, we fabricated modified cyanate ester (CE) and carbon/CE composites by the incorporation of reduced graphene oxide-TiO2 (rGO-TiO2) nanoparticles and studied their resistance performance to electronic radiation. Compared with the carbon/TiO2/CE composite, the interlayer shear strength of the resulting carbon/rGO-TiO2/CE composite increased by 10.4% and its mass loss reduced by 16.5%. Scanning electron microcopy (SEM) images showed that there are more cracks at the fiber and resin interfaces of carbon/CE than at the interfaces of carbon/rGO-TiO2/CE after irradiation. X-ray photoelectron spectroscopy (XPS) investigation showed that irradiation with 160 keV electrons could break the chemical bonds at the surface layer of the pristine CE resin, which is effectively prevented by the incorporation of rGO-TiO2 nanoparticles. © The Royal Society of Chemistry 2015. Source

Zhang Y.,Northeastern University China | Huang H.,Northeastern University China | Huang H.,Chinese Academy of Sciences | Li C.,Shanghai Institute of Spacecraft Equipment
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2014

The pumping speed curves of a variety of rotary vacuum pump, provided by the manufacturers, were empirically fitted with polynomials and digitized for the designer of vacuum system. The program of data-fitting and digitization was written in Visual Basic 6.0. The newly-digitized pumping speed provides a total solution to the common problem that in conventional design of a vacuum system, the pumping-speed range involved is routinely assumed to be a constant in the calculation, which often results in a large error. As an example, the pumping speed curve of 2XZ-8 rotary vane pump was fitted and digitized; and the calculation precision increased by about 22%. In addition, the calculation precision for the pump-down time and average pipeline pressure were also considerably improved. Source

Wang D.,Central South University | Wang X.,Central South University | Zhou P.,Central South University | Wu Z.,Central South University | And 2 more authors.
Powder Technology | Year: 2014

In the present work, experimental trials were carried out to investigate the influence of packing density on performance of porous wick for loop heat pipe (LHP). Carbonyl nickel powders with an average size of 1.19μm were used as raw materials. During the filling of powders the graphite mold was put on a mechanical vibrator for different times to get different packing densities. The results show that the porosity, average pore size and permeability decrease with the increasing packing density, respectively. However, the capillary pressure increases with it. And there are no obvious effects on micro-structure and shrinkage ratio. Moreover, the packing density has complex effects on thermal property. After the optimization of parameters, the cylindrical wick with porosity of 59%, average pore size of 1.41μm, permeability of 1.25×10-13m2, capillary pressure of 204kPa and excellent thermal property could be realized. © 2014 Elsevier B.V. Source

Liu C.-L.,Northwestern Polytechnical University | Zhu H.-R.,Northwestern Polytechnical University | Zhang X.,Shanghai Institute of Spacecraft Equipment | Xu D.-C.,Northwestern Polytechnical University | Zhang Z.-W.,Northwestern Polytechnical University
International Journal of Heat and Mass Transfer | Year: 2014

Film cooling performances of the cylindrical film holes and the laid-back film holes on the turbine blade leading edge model are investigated in this paper. Experimental measurements have been carried out to investigate the influence of the inclined angle in the spanwise direction (i.e. radial angle for a blade in the engine) on the film cooling performances of these two kinds of holes. Three rows of holes are arranged in a semi-cylinder model which is used to model the blade leading edge. Two inclined angles and three blowing ratios are tested. Transient heat transfer measurement technique with double thermochromic liquid crystals is employed in the present experiment. The results show that the trajectory of the film jets in the leading edge region deviates from the mainstream direction to the spanwise direction gradually as the blowing ratio increases. Under large blowing ratio, more area can benefit from the film protection and the film cooling effectiveness distribution is more uniform than those under small blowing ratio, while the heat transfer coefficient is also higher. The basic distribution features of heat transfer coefficient are similar for all the tested models. The heat transfer coefficient in the region where the jet core flows through is relatively lower, while the heat transfer coefficient in the jet edge region is relatively higher. Compared with the cylindrical holes, the jets from the laid-back holes have better film coverage and meanwhile make more area have relatively higher heat transfer coefficient, especially under large blowing ratio. Under the same blowing ratio, the jets from film holes with small radial angle can attach on the wall surface better and give higher film cooling effectiveness in the region close to the hole exit than the film holes with large radial angle, while they also produce relatively higher heat transfer coefficient. © 2013 Elsevier Ltd. All rights reserved. Source

Wen X.,Shanghai Institute of Spacecraft Equipment | Wen X.,Zhejiang University | Chen Z.-W.,Zhejiang University | He H.-N.,Zhejiang University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

A continuous contact force model was built in order to investigate joint clearance effects on the dynamics of two-axis hydraulic vibration test system. The test system with clearance joint was imported into the software ADAMS for dynamic simulation, and an experimental set-up was designed and built to achieve some experimental validations under the simple harmonic excitation inputs with different phases. The results indicate that the coupling vibration effect between two exciters leads to the apparent fluctuation of steady response of accelerations in the case of certain clearance size and with excitations out of phase, meanwhile, the rapid increase of peak acceleration happens when the excitation frequency and excitation amplitude increase. Thus, the selection of appropriate clearance size in revolute joint for two-axis hydraulic vibration test system is a crucial step for eliminating the non-linear influence. Source

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