Shanghai Marine Equipment Research Institute
Shanghai Marine Equipment Research Institute
Guo Z.,University of Shanghai for Science and Technology |
Xin Y.,Shanghai Marine Equipment Research Institute |
Li L.,University of Shanghai for Science and Technology
Shanghai Ligong Daxue Xuebao/Journal of University of Shanghai for Science and Technology | Year: 2017
The physical properties of methane change drastically and the phenomenon of phase change vanishes under supercritical pressure, so the heat exchange process is extremely complex. The heat transfer characteristics of supercritical methane in a heating vertical circular tube were investigated numerically. The thermal performance and transport properties of supercritical methane were obtained by introducing the material model of methane in the refrigerant properties software REFPROP. The results show that it is advantageous to the heat transfer when the averaged fluid temperature is close to the critical temperature and the wall temperature is higher than the critical temperature. And the heat transfer coefficient increases with the decrease of pressure. High heat flux and low mass flow rate will cause the deterioration of heat transfer. Then the influence of buoyancy on the heat transfer was studied carefully and the buoyancy judgment standard suitable for methane was obtained. It is found that the buoyancy which changes the distribution of radial velocity and inhibits the generation of turbulent kinetic energy weakens the convective heat transfer. © 2017, Editorial Board of Journal of USST. All right reserved.
Kang C.,Jiangsu University |
Mao N.,Jiangsu University |
Zhang W.,Shanghai Marine Equipment Research Institute |
Gu Y.,Jiangsu University
Annals of Nuclear Energy | Year: 2017
The cavitation performance of the centrifugal pump depends significantly on geometrical traits of the impeller blade. An investigation is performed on the centrifugal condensate pump which is featured by operating under cavitation condition. Both experimental and numerical techniques are utilized. Three impeller schemes are devised to improve the cavitation performance. Pump head, cavitation and flow parameter distribution are investigated systematically. Experimental results show that the impeller with five long and five short blades possesses the smallest critical value of net positive suction head at rated flow rate. It is further proved that this impeller maintains the most desirable cavitation performance over the entire flow rate range. Both hydraulic and cavitation performance of the impeller equipped with nine blades of three kinds of length are low relative to the other schemes. Cavities in the pump impeller are produced at the suction side of long blades and approaching the blade inlet, while cavities are absent near the inlet of the short blades. The correlation between pressure distribution and cavitation is manifested at impeller inlet. Long blades contribute to the enhancement of flow uniformity, but the low-pressure area immediately upstream of the blade inlet is enlarged due to narrowed inter-blade area, as is evident in the three pump impellers. © 2017 Elsevier Ltd
Zhang J.,Harbin Engineering University |
Qiao G.,Harbin Engineering University |
Wang C.,Shanghai Marine Equipment Research Institute
Proceedings - 2012 5th International Symposium on Computational Intelligence and Design, ISCID 2012 | Year: 2012
Acoustic modem is one of the key components of underwater acoustic communication, in order to adapt to the complex and changeable acoustic environment and complete the underwater sensor network, an intelligent modem management platform is needed to achieve the parameter adjustment and the network protocol operation, while the commercial underwater acoustic modems which are already in use are hard to meet this requirement. In this paper, we designed and implemented an intelligent underwater acoustic modem management platform, based on the chip ARM6410. The platform supports the executable program written by users, and can complete the functions of modem state control, data storage and forwarding, and network protocol implementation. Experiments on testing capability of the platform were conducted in the yellow sea, results show that the management platform performs well. © 2012 IEEE.
Zhang X.,Shanghai Marine Equipment Research Institute |
Yang P.,Shanghai Marine Equipment Research Institute
Qiche Gongcheng/Automotive Engineering | Year: 2011
A sliding mode control strategy for the powertrain of a series hybrid electric vehicle (SHEV) is presented with a desired battery charge curve set. Two robust fixed-boundary-layer sliding mode controllers are configured in powertrain control system for controlling engine speed and torque respectively, to make engine operate in optimal efficiency region. Meanwhile a proper battery charging curve is designed to help extend battery life. The results of simulation with software ADVISOR verify the effectiveness of the strategy proposed and its superiority over the conventional one.
Hu J.,Shanghai Marine Equipment Research Institute |
Qiu Z.,Beihang University |
Su T.C.,Florida Atlantic University
Journal of Sound and Vibration | Year: 2011
Axisymmetric vibrations of a viscous-fluid-filled piezoelectric sphere, with radial polarization, submerged in a compressible viscous fluid medium are investigated. The oscillations are harmonically driven by an axisymmetrically applied electric potential difference across the surface of the shell. A theoretical formulation cast the piezoelectric shell problem into a corresponding problem of an elastic shell with the contribution of piezoelectricity confined to slightly modified in vacuum natural frequencies and their associated mode shapes. It is noted that the fluid inside the shell will have a dominating influence on the vibrational characteristics of the submerged shell. The circular components of the natural frequency spectra closely follow those of the fluid-filled shell in vacuo. Furthermore, the corresponding damping components of those natural frequencies are rather small, making acoustic radiation and under-damped oscillation possible for an infinite number of natural frequencies. The characteristics of natural frequencies are elucidated using a fluid-filled polyvinglindene fluoride (PVDF) shell submerged in both air and water as an example. It is found that the piezoelectric parameters that contribute to the shells natural frequencies is of a small order for thin PVDF shells, and is thereby negligible. It is noted that, with the mechanical constant typically associated with piezoelectric materials, fluid viscosity could have a significant effect on some vibrations. In certain cases, a natural frequency associated with a minimum viscous damping and a maximum of total damping (indicating highly efficient acoustic radiation) is possible with such a frequency. The vibrational characteristics, fluid loading, and energy flow are evaluated for a fluid-filled PVDF shell submerged in air and water. The inclusion of fluid inside the shell is shown to produce various narrow band peaks responses, vibrational absorbing frequencies, and non-dissipating frequencies. Those vibrational characteristics could have many potential applications. For example, the interior fluid could offer the option of generating a desired narrow band near resonant sound radiation while keeping power dissipation due to fluid viscosity to a minimum. Those well-defined narrow band characteristics also open up possibilities of using a vibrating, fluid-filled shell as a micro scale sensor for sensing and detection applications. © 2011 Elsevier Ltd. All rights reserved.
Li N.,Xi'an University of Technology |
Xu J.,Shanghai Marine Equipment Research Institute |
Man W.,Xi'an University of Technology
China International Conference on Electricity Distribution, CICED | Year: 2016
Rapid and correct detection of harmonics is the premise of suppressing harmonics in power system, and is also of great significance to the improvement of power quality. A new detection method for the harmonics based on TT-transform (Time-Time Transform) is proposed in this paper. In view of the instantaneous data of the power system, TT-transform is firstly used and diagonal element of the transformation result is got, then, FFT transform is used on diagonal element to extract the characteristic quantities of harmonics such as harmonic order, amplitude, and the start and end time of transient state, etc. The fundamental principle and characteristics of TT-transform are firstly presented, and then the detection method of harmonics in power system based on TT-transform is elaborated in detail. Finally, the steady harmonics, transient harmonics and the harmonics with noise are simulated respectively. The simulation results verify the efficiency of the proposed method, and show that it is also characterized by simple utilization, high accuracy, and good anti-interference performance. © 2016 IEEE.
Wu H.,Shanghai JiaoTong University |
Jiang W.,Shanghai JiaoTong University |
Zhang Y.,Shanghai JiaoTong University |
Lu W.,Shanghai Marine Equipment Research Institute
Journal of the Acoustical Society of America | Year: 2014
Application of modal expansion approach for the exterior acoustic field has drawn wide research interests in recent years. This is primarily due to the acoustic radiation modes (ARM) that can diagonalize the impedance matrix, hence significantly simplifying the computation of radiated sound power. The orthogonal ARM are typically calculated via a standard eigenvalue analysis of the impedance matrix, which normally leads to numerical difficulties especially for wideband frequency and large scale problems. In this paper, a theory of mapped ARM is proposed to avoid the cumbersome computation of ARM for convex structures. A mapping relationship between the ARM on the surface of an equivalent spherical source and the mapped ARM on the surface of a convex structure is obtained based on the equivalent source method, multipole expansion method, and boundary integral method. Furthermore, analytical expressions for the radiated sound power of structures vibrating in its mapped ARM as well as that of spheres are derived. Finally, a simple method is proposed to approximate the radiated sound power based on the modal decomposition method and the mapping relationship. Numerical simulations are conducted to validate the accuracy and efficiency of the proposed approach, and different vibrating structures with various geometries are considered. Results demonstrate that the proposed methodology for calculating the radiated sound power of convex structures is very efficient and accurate as compared with the traditional approach. © 2014 Acoustical Society of America.
Gu Y.,Zhejiang University |
Zheng W.,Shanghai Marine Equipment Research Institute |
Li W.,Zhejiang University |
He X.,Zhejiang University
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC | Year: 2015
DC microgrids may have time-varying system structures and operation patterns due to the flexibility and uncertainty of microsources. This feature poses a challenge to conventional stability analysis methods, which are based on fixed and complete system models. To solve this problem, the concept of self-disciplined stabilization is introduced in this paper. A common stability discipline is established using the passivity-based control theory, which ensures that the microgrid is always stable as long as this discipline is complied with by each individual converter. In this way, the stabilization task is localized to avoid investigating the entire microgrid, thereby providing immunity against system variations. Moreover, a passivity margin criterion is proposed to further enhance the stability margin of the self-disciplined control. The modified criterion imposes a tighter phase restriction to provide explicit phase margins and prevent under-damped transient oscillations. In line with this criterion, a practical control algorithm is also derived, which increases the converter's passivity through voltage feed forward. The major theoretical conclusions are verified by a laboratory DC microgrid test bench. © 2015 IEEE.
Shao D.,Harbin Engineering University |
Hu F.,Shanghai Marine Equipment Research Institute |
Wang Q.,Harbin Engineering University |
Pang F.,Harbin Engineering University |
Hu S.,Harbin Engineering University
Composite Structures | Year: 2016
The aim of this work is to present a unified and analytical solution for the transient response analysis of moderately thick general cross-ply composite laminated rectangular plates with general boundary restraints by using the method of reverberation ray matrix (MRRM). The wave solutions are constructed by the exact closed form solutions of the governing differential equations on the basis of the first-order shear deformation theory (FSDT). The reverberation ray matrix can be easily obtained by using the MRRM together with the wave solutions, boundary conditions and dual coordinates of the composite plate. As one merit of this paper, the spring boundary technology is applied to imitate the general boundary restraints and eliminate the barrier of the reverberation ray matrix. Then, the early short time transient responses of the composite laminated rectangular plate with general boundary restraints are obtained by using the Fast-Fourier transform (FFT) algorithm. The excellent accuracy, reliability and efficiency of the current solution are fully demonstrated and verified through numerical examples involving plates with different boundary conditions. A variety of new parameter studies for the composite laminated rectangular plate with different elastic restraint parameters, layer numbers, orthotropic ratios as well as various impact load types are analyzed. © 2016 Elsevier Ltd.
LiU L.Y.,Shanghai Ocean University |
Shi X.Z.,Shanghai Marine Equipment Research Institute
Advanced Materials Research | Year: 2014
This paper presents the simulation of a solar-powered continuous adsorption air-conditioning system with the working pair of silica gel and water. In order to make the adsorption system more suitable to use solar energy to supply cooling continuously during daytime, a new adsorption system without refrigerant valves is being developed in SJTU recently. By using this system, the problem such as pressure drop along refrigerant circuit can be resolved. The frequent switches of refrigerant valves can also be omitted. The daytime long simulation results (ranging from 6:00 to 18:00) demonstrate that the solar-powered adsorption system can supply a fairly steady cooling output all the time. Based on the results, parametric study is also undertaken to optimize the design. © (2014) Trans Tech Publications, Switzerland.