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Optimization of equimolar reverse constant-temperature mass-diffusion process for minimum entransy dissipation

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Science China(Technological Sciences) 2016年第12期59卷 1867-1873页

作者： XIA Shao Jun CHEN Lin Gen SUN Feng Rui Institute of Thermal Science and Power engineering Naval University of Engineering Military Key Laboratory for naval Ship Power engineering Naval University of Engineering college of Power engineering Naval University of Engineering

The mass entransy describes the mass-diffusion ability of the solution system, and the mass-diffusion process with the finite concentration difference always leads to the mass-entransy dissipation. This paper studies the equimolar reverse constant-temperature mass-diffusion process with Fick's law( g∝Δ(c)). The optimal concentration paths for the MED(Minimum Entransy Dissipation) are derived and compared with those for the MEG(Minimum Entropy Generation) and CCR(Constant Concentration Ratio) operations. It is indicated that the strategy of the MED is equivalent to that of the CCD(Constant Concentration Difference) of the same component; whether the MED or the MEG is selected as the optimization objective, the strategy of the CCD is much better than that of the CCR.

关键词： mass entransy finite time thermodynamics equimolar reverse mass-diffusion Fick's mass-diffusion law optimal concentration path generalized thermodynamic optimization

Influences of external heat transfer and Thomson effect on the performance of TEG-TEC combined thermoelectric device

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Science China(Technological Sciences) 2018年第10期61卷 1600-1610页

作者： FENG YuanLi CHEN LinGen MENG FanKai SUN FengRui Institute of Thermal Science and Power engineering Naval University of Engineering Military Key Laboratory for naval Ship Power engineering Naval University of Engineering college of Power engineering Naval University of Engineering

A thermodynamic model of a thermoelectric generator(TEG)-driven thermoelectric cooler(TEC) device considering Thomson effect and external heat transfer(HT) is established based on the combination of non-equilibrium and finite time thermodynamic theories. The expressions of cooling capacity and coefficient of performance(COP) are obtained. Performances are compared with and without considering Thomson effect using numerical optimization method. The influences of Thomson effect on the optimal performances, optimum allocations of thermoelectric(TE) element number and HT surface area are discussed. The results indicate that Thomson effect decreases the maximum cooling capacity and COP. More TE elements should be allocated to TEG, and more HT area should be allocated to the heat exchanger(HEX) of TEG, the hot-side HEX of TEG and the cold-side HEX of TEC in the design of the device considering Thomson effect. The results obtained can be used to help design TEG-TEC devices.

关键词： thermoelectric generator thermoelectric cooler combined thermoelectric device performance optimization non-equilibrium thermodynamics finite time thermodynamics

An improved lattice Boltzmann model for high gas and liquid density ratio in composite grids

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Theoretical & Applied Mechanics Letters 2018年第5期8卷 326-333,362页

作者： Shaojun Zhang Wanqing Wu Qinggong Zheng Marine engineering college Dalian Maritime University college of naval architecture and Marine engineering Shandong Jiaotong University

Lattice Boltzmann method is one of the widely used in multiphase fluid ***,the two main disadvantages of this method are the instability of numerical calculations due to the large density ratio of two phases and impossibility of the temperature distribution to be fed back into the velocity distribution function when the temperature is *** on the combination prescribed by Inamuro,the large density ratio two-phase flow model and thermal model makes the density ratio of the model simulation to be increased to 2778:1 by optimizing the interface distribution function of two-phase which improves the accuracy of differential *** phase transition term is added as source term into the distribution function controlling two phase order parameters to describe the temperature effect on the gas-liquid phase *** latent heat generated from the phase change is also added as a source term into the temperature distribution function which simulates the movement of the flow under the common coupling of density,velocity,pressure and *** density and the temperature distribution of single bubble are *** of the simulation results with experimental results indicates a good agreement pointing out the effectiveness of the improved model.

关键词： Lattice Boltzmann model Density ratio Composite grids Bubble motion Temperature effect

Performance deterioration modeling and optimal preventive maintenance strategy under scheduled servicing subject to mission time

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Chinese Journal of Aeronautics 2014年第4期27卷 821-828页

作者： Li Dawei Zhang Zhihua Zhong Qianghui Zhai Yali Department of Weapon engineering Naval University of Engineering Office of Research & Development Naval University of Engineering Department of Equipment Economics & Management Naval University of Engineering college of Science Naval University of Engineering

Servicing is applied periodically in practice with the aim of restoring the system state and prolonging the lifetime. It is generally seen as an imperfect maintenance action which has a chief influence on the maintenance strategy. In order to model the maintenance effect of servicing, this study analyzes the deterioration characteristics of system under scheduled servicing. And then the deterioration model is established from the failure mechanism by compound Poisson process. On the basis of the system damage value and failure mechanism, the failure rate refresh factor is proposed to describe the maintenance effect of servicing. A maintenance strategy is developed which combines the benefits of scheduled servicing and preventive maintenance. Then the optimization model is given to determine the optimal servicing period and preventive maintenance time, with an objective to minimize the system expected life-cycle cost per unit time and a constraint on system survival probability for the duration of mission time. Subject to mission time, it can control the ability of accomplishing the mission at any time so as to ensure the high dependability. An example of water pump rotor relating to scheduled servicing is introduced to illustrate the failure rate refresh factor and the proposed maintenance strategy. Compared with traditional methods, the numerical results show that the failure rate refresh factor can describe the maintenance effect of servicing more intuitively and objectively. It also demonstrates that this maintenance strategy can prolong the lifetime, reduce the total lifetime maintenance cost and guarantee the dependability of system.

关键词： Dependability Imperfect maintenance Preventive maintenance Reliability Scheduled servicing

Research Progress of Tip Winglet Technology in Compressor

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Journal of Thermal Science 2021年第1期30卷 18-31页

作者： ZHONG Jingjun WU Wanyang HAN Shaobing Merchant Marine college Shanghai Maritime UniversityShanghai 201306China naval architecture and Ocean engineering college Dalian Maritime UniversityDalian 116026China

In the present study,the research progress of tip winglets that control tip clearance leakage flow in compressors is ***,the effects of tip leakage flow on the aerodynamic performance of the compressor are ***,the development of tip winglet technology is ***,a series of studies on compressor tip winglet technology are ***,the effects of tip winglets on the aerodynamic performance of rectangular cascades of low-speed and high-subsonic compressors,subsonic compressor rotor and transonic compressor rotor are discussed,respectively,and the control effect of tip winglet technology combined with tip groove design on tip leakage is ***,the subsequent development direction and research prospect of compressor tip winglet technology are presented.

关键词： blade tip winglet compressor tip leakage flow tip leakage vortex

PARAMETRIC IDENTIFICATION AND SENSITIVITY ANALYSIS FOR AUTONOMOUS UNDERWATER VEHICLES IN DIVING PLANE

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Journal of Hydrodynamics 2012年第5期24卷 744-751页

作者： XU Feng ZOU Zao-jian YIN Jian-chuan CAO Jian School of naval architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240China School of naval architecture Ocean and Civil Engineering and State Key Laboratory of Ocean EngineeringShanghai Jiao Tong University Shanghai 200240 China college of Shipbuilding engineering Harbin Engineering University Harbin 150001 China

The inherent strongly nonlinear and coupling performance of the Autonomous Underwater Vehicles （AUV）, maneuvering motion in the diving plane determines its difficulty in parametric identification. The motion parameters in diving plane are obtained by executing the Zigzag-like motion based on a mathematical model of maneuvering motion. A separate identification method is put forward for parametric identification by investigating the motion equations. Support vector machine is proposed to estimate the hydrodynamic derivatives by analyzing the data of surge, heave and pitch motions. Compared with the standard coefficients, the identified parameters show the validation of the proposed identification method. Sensitivity analysis based on numerical simulation demonstrates that poor sensitive derivative gives bad estimation results. Finally the motion simulation is implemented based on the dominant sensitive derivatives to verify the reconstructed model.

关键词： parametric identification Autonomous Underwater Vehicles (AUVs) support vector machine sensitivity analysis

Effect of Meridional Characteristic Angle on Aerodynamic Performance of Ram-Rotor

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Journal of Thermal Science 2020年第3期29卷 753-762页

作者： HAN Ji'ang GUAN Jian ZHONG Jingjun CHEN Luting naval architecture and Ocean engineering college Dalian Maritime UniversityDalian 116026China Merchant Marine college Shanghai Maritime UniversityShanghai 201306China

A kind of meridional concept which has a shape of contraction-expansion(Con-Exp)was applied to the ram-rotor in the paper,and detailed numerical simulation to understand the impact of meridional shape and geometric characteristic angle on the aerodynamic behavior of ram-rotors has been *** to baseline,there was a positive effect in intensifying shock train and suppressing low momentum fluid in Con-Exp scheme,and the pressure ratio and efficiency of Con-Exp scheme increased by 2.075%and 3.160%,*** the contracting angle was increasing,supersonic flow at and after throat region accelerated remarkably,and the static pressure rise was decreased *** terminating shock train was transformed to terminating shock,and the efficiency of ram-rotor was unfavorable to improve due to low throttle *** expanding angle rose,the terminating shock moved forward and turned to shock train *** pressure rise capacity and throttling ability of ram-rotor were *** low momentum fluid was accumulated near the middle and upper flow-path,yielding greater flow loss at large expanding angle.

关键词： ram-rotor meridional shape contracting angle expanding angle numerical simulation

Numerical Forecasting of Icing on Structural Components of Offshore Platforms in Polar Regions

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China Ocean engineering 2021年第4期35卷 588-597页

作者： BAI Xu SHEN Jie XUE Yan-zhuo SHU Yuan-chao School of naval architecture&Ocean engineering Jiangsu University of Science and TechnologyZhenjiang 212003China college of Shipbuilding engineering Harbin Engineering UniversityHarbin 150001China

The Polar Regions are rich in natural resources but experience an extremely cold *** surfaces of offshore platforms operating in the Polar Regions are prone to *** develop solutions to this problem of surface icing,the influence of both the liquid water concentration of the surrounding atmosphere and the average water droplet diameter on the formation of ice on two major structural components of offshore platforms was analyzed using a combination of Fluent and *** showed that at a wind speed of 7 m/s,as the concentration of liquid water in the air increases from 0.05 to 0.25 g/m3,the amount and thickness of the icing on the surfaces of the two structural components increase *** a wind speed of 7 m/s and when the size of the average water droplet diameter is 20–30(30–35)μm,as the average water droplet diameter increases,the amount and thickness of the icing on the surfaces of the two structural components increase(decrease)gradually.

关键词： offshore platform in cold regions icing numerical analysis icing thermodynamic model icing calculation process

Non-deterministic fatigue life analysis using convex set models

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Science China(Physics,Mechanics & Astronomy) 2013年第4期56卷 765-774页

作者： SUN WenCai YANG ZiChun LI KunFeng college of Power engineering Naval University of Engineering

The non-probabilistic approach to fatigue life analysis was studied using the convex models-interval, ellipsoidal and multiconvex models. The lower and upper bounds of the fatigue life were obtained by using the second-order Taylor series and Lagrange multiplier method. The solving process for derivatives of the implicit life function was presented. Moreover, a median ellipsoidal model was proposed which can take into account the sample blind zone and almost impossibility of concurrence of some small probability events. The Monte Carlo method for multi-convex model was presented, an important alternative when the analytical method does not work. A project example was given. The feasibility and rationality of the presented approach were verified. It is also revealed that the proposed method is conservative compared to the traditional probabilistic method, but it is a useful complement when it is difficult to obtain the accurate probability densities of parameters.

关键词： non-deterministic fatigue life convex set model non-probabilistic Taylor expansion Monte Carlo