检索结果-南通市图书馆

Cavitation Optimization for a Centrifugal Pump Impeller by Using Orthogonal Design of Experiment

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2017年第1期30卷 103-109页

作者： pei ji YIN Tingyun YUAN Shouqi WANG Wenjie WANG jiabin National Research Center of Pumps Jiangsu UniversityZhenjiang 212013China Shandong Shuanglun Co. Ltd.Weihai 264203China

Cavitation is one of the most important performance of centrifugal pumps. However, the current optimization works of centrifugal pump are mostly focusing on hydraulic efficiency only, which may result in poor cavitation performance. Therefore, it is necessary to find an appropriate solution to improve cavitation performance with acceptable efficiency. In this paper, to improve the cavitation performance of a centrifugal pump with a vaned diffuser, the influence of impeller geometric parameters on the cavitation of the pump is investigated using the orthogonal design of experiment （DOE） based on computational fluid dynamics. The impeller inlet diameter D1, inlet incidence angle Aft, and blade wrap angle ~0 are selected as the main impeller geometric parameters and the orthogonal experiment of L9（3＂3） is performed. Three-dimensional steady simulations for cavitation are conducted by using constant gas mass fraction model with second-order upwind, and the predicated cavitation performance is validated by laboratory experiment. The optimization results are obtained by the range analysis method to improve cavitation performance without obvious decreasing the efficiency of the centrifugal pump. The internal flow of the pump is analyzed in order to identify the flow behavior that can affect cavitation performance. The results show that D1 has the greatest influence on the pump cavitation and the final optimized impeller provides better flow distribution at blade leading edge. The final optimized impeller accomplishes better cavitation and hydraulic performance and the NPSHR decreases by 0.63m compared with the original one. The presented work supplies a feasible route in engineering practice to optimize a centrifugal pump impeller for better cavitation performance.

关键词： cavitation optimization computational fluid dynamics orthogonal design of experiment range analysis

Experimental Investigation on the Flow-induced Noise under Variable Conditions for Centrifugal Pumps

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第3期25卷 456-462页

作者： YUAN Shouqi YANG Jun YUAN jianping LUO Yin pei ji Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang 212013China

With extensively using of centrifugal pumps,noise generation in these pumps is increasingly receiving research attention in recent *** noise sources in centrifugal pumps are mainly composed of mechanical noise and flow-induced *** the study of flow-induced noise has become a hotspot and important domain in the *** flow-induced noise closely related to the inner pressure pulses and vibration of volute in pumps,therefore,it is necessary to research the interaction and mechanism among *** investigate the relationships,a test system is designed which includes a test loop and a measurement *** hydrophones and pressure sensors are installed on the outlet of the pump and vibration acceleration sensors are disposed on the pump *** these instruments,the signals of noise,pressure pulses and vibration are collected and *** results show that the level of flow-induced noise becomes smaller as the flow increment during low flow rate operations,and it is steadily close to the design point,then it increases with the growing of flow rate in high flow rate ***,there are some similar peak points in the power spectrum charts of noise,pressure pulses and *** broadband noise at low flow rate is mostly focused on the region of 0-40 times shaft frequency,which is mostly made by rotating stall and vortex;while the noise at high flow rate conditions is focused on the region of 60-100 times shaft frequency,which may be mostly made by *** proposed research is of practical and academic significance to the study of noise reduction for centrifugal pumps.

关键词： centrifugal pump flow-induced noise pressure pulses vibration of volute

Ince-Strutt Stability Charts for Ship Parametric Roll Resonance in Irregular Waves

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2017年第4期31卷 447-457页

作者： ZHANG Xiao YANG He-zhen XIAO Fei XU pei-ji National Key Laboratory on Ship Vibration &Noise China Ship Development and Design Center State Key Laboratory of Ocean Engineering School of Naval Architecture.Ocean and Civil EngineeringShanghai Jiao Tong University School of Civil and Environmental Engineering Nanyang Technological University

Ince-Strutt stability chart of ship parametric roll resonance in irregular waves is conducted and utilized for the exploration of the parametric roll resonance in irregular waves. Ship parametric roll resonance will lead to large amplitude roll motion and even wreck. Firstly, the equation describing the parametric roll resonance in irregular waves is derived according to Grim’s effective theory and the corresponding Ince-Strutt stability charts are obtained. Secondly, the differences of stability charts for the parametric roll resonance in irregular and regular waves are compared. Thirdly, wave phases and peak periods are taken into consideration to obtain a more realistic sea condition. The influence of random wave phases should be taken into consideration when the analyzed points are located near the instability boundary. Stability charts for different wave peak periods are various. Stability charts are helpful for the parameter determination in design stage to better adapt to sailing condition. Last, ship variables are analyzed according to stability charts by a statistical approach. The increase of the metacentric height will help improve ship stability.

关键词： parametric instability parametric rolling multi-frequency irregular waves Ince-Strutt stability chart

Analysis and optimization based on a sex pheromone and pesticide pest model with gestation delay

在线全文

学校读者我要写书评

暂无评论

International Journal of Biomathematics 2019年第5期12卷 115-136页

作者： Shu Xiang Yongzhen pei Xiyin liang School of Mathematical Sciences Tianjin Polytechnic University Tianjin 300387 P.R.China

Sex pheromone,aiming at mating disruption (MD),being species specific and leaving no toxic residues in the produce grown,offers an attractive alternative to conventional *** this paper,by incorporating the gestation delay and sex pheromone,we explore the impact of MD control on the dynamic behaviors of pest ***,the boundness,stability and bifurcation of system are ***,an optimal control problem based on sex pheromone and pesticide is transformed into an equivalent optimal parameter selection problem by introducing the constrain violation ***,the gradients of the cost function with respect to the dose of sex pheromone and the killing rate are ***,simulations are executed to validate the validity of our ***,our results indicate that gestation delay increases the extinction risk of the population and liberating sex pheromone destroys the stability of equilibrium states.

关键词： Sex pheromone gestation constrain violation function stability optimization.

Study on a novel flat renewal supported liquid membrane with D2EHPA and hydrogen nitrate for neodymium extraction

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rare Earths 2012年第1期30卷 63-68页

作者： pei liang WANG Liming YU Guoqiang Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Faculty of Water Resources and Hydraulic Power Xi'an University of TechnologyXi'an 710048China School of Environment and Chem-istry Engineering Xi'an Polytechnic UniversityXi'an 710048China

The Nd（III） extraction in flat renewal supported liquid membrane（FRSLM）,with polyvinylidene fluoride membrane and renewal solution including HNO3 solution as the stripping solution and di（2-ethylhexyl） phosphoric acid（D2EHPA） dissolved in kerosene as the membrane solution,was *** effects of pH in the feed phase,volume ratio of membrane solution to stripping solution,concentra-tion of HNO3 solution and concentration of carrier in the renewal phase on extraction of Nd（III） were also studied,*** a result,the optimum extraction conditions of Nd（III） were obtained when concentration of HNO3 solution was 4.00 mol/L,concentration of D2EHPA was 0.100 mol/L,and volume ratio of membrane solution to stripping solution was 1.00 in the renewal phase,and pH was 4.60 in the feed *** initial concentration of Nd（III） was 2.00×10-4 mol/L,the extraction percentage of Nd（III） was up to 92.9% in 75 min.

关键词： membrane extraction flat renewal supported liquid membrane di(2-ethylhexyl) phosphoric acid neodymium extraction flux rare earths

Numerical and Experimental Study on Flow-induced Noise at Blade-passing Frequency in Centrifugal Pumps

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2014年第3期27卷 606-614页

作者： YANG Jun YUAN Shouqi YUAN jianping SI Qiaorui pei ji Research Center of Fluid Machinery Engineering and Technology Jiangsu University

With the increasing noise pollution, low noise optimization of centrifugal pimps has become a hot topic. However, experimental study on this problem is unacceptable for industrial applications due to unsustainable cost. A hybrid method that couples computational fluid dynamics （CFD） with computational aeroacoustic software is used to predict the flow-induced noise of pumps in order to minimize the noise of centrifugal pumps in actual projects. Under Langthjem＇s assumption that the blade surface pressure is the main flow-induced acoustic source in centrifugal pumps, the blade surface pressure pulsation is considered in terms of the acoustical sources and simulated using CFX software. The pressure pulsation and noise distribution in the near-cutoff region are examined for the blade-passing frequency （BPF） noise, and the sound pressure level （SPL） reached peaks near the cutoff that corresponded with the pressure pulsation in this region. An experiment is performed to validate this prediction. Four hydrophones are fixed to the inlet and outlet ports of the test pump to measure the flow-induced noise from the four-port model. The simulation results for the noise are analyzed and compared with the experimental results. The variation in the calculated noise with changes in the flow agreed well with the experimental results. When the flow rate was increased, the SPL first decreased and reached the minimum near the best efficient point （BEP）; it then increased when the flow rate was further increased. The numerical and experimental results confirmed that the BPF noise generated by a blade-rotating dipole roughly reflects the acoustic features of centrifugal pumps. The noise simulation method in current study has a good feasibility and suitability, which could be adopted in engineering design to predict and optimize the hydroacoustic behavior of centrifugal pumps.

关键词： centrifugal pumps flow-induced noise prediction blade-passing noise blade surface pressure pulsations

Anisotropic Mechanical Response of Nacre to Heat Treatment Under Indentation:Effect of Structural Orientation

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2024年第3期21卷 1453-1464页

作者： Simin liang Yingying Li Hongmei ji Xiaowu Li Department of Materials Physics and Chemistry School of Materials Science and EngineeringKey Laboratory for Anisotropy and Texture of MaterialsMinistry of EducationNortheastern UniversityShenyang110819China

It is generally considered that heat treatments have a negative impact on the mechanical properties of nacre due to thermal decomposition of the organic ***,the present work investigated the microindentation behavior on fresh and heat-treated nacres from two orthogonal directions,and the results demonstrate that both hardness value and damage tolerance can remain almost unchanged on the cross-section with the organic matrix degeneration,despite a significant deterioration on the platelet *** analyses suggest that the anisotropic response of indentation behavior to heat treatment in nacre is primarily caused by its structural ***,compared with a single layer of irregular interplatelet interfaces in cross-sectional specimens,the multiple layers of parallel interlamellar interfaces in in-plane specimens exhibit a much greater ability to impede indenter-triggered destruction,and heat treatments would reduce the in-plane hardness but nearly have no effect on the cross-sectional ***,the deeper embedding of platelets in cross-sectional specimens enhances their resistance to interface cracking caused by organic matrix degradation at high temperatures,leading to a reduced sensitivity to ***,the indentation behavior of nacre shows different tendencies in response to variations in the organic matrix state along normal and parallel directions.

关键词： Nacre Structural orientation Heat treatment Indentation behavior Organic matrix

Stripping dispersion hollow fiber liquid membrane containing carrier PC-88A and HNO_3 for the extraction of Sm^(3+)

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2012年第1期23卷 101-104页

作者： liang pei Li Ming Wang Wei Guo Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China School of Environment and Chemistry Engineering Xi'an Polytechnic UniversityXi'an 710048China Faculty of Water Resources and Hydraulic Power Xi'an University of TechnologyXi'an 710048China

Stripping dispersion hollow fiber liquid membrane system（SDHFLM） containing feed phase adding acetate buffer solution and dispersion solution with HNO_3 solution as the stripping solution and membrane solution of 2-ethyl hexyl phosphoric acid-mono-2-ethylhexyl ester（PC-88A） dissolved in kerosene,has been studied for the extraction of Sm^（3＋）.Many factors including pH value, volume ratio of membrane solution to stripping solution（OAV） and carrier concentration on Sm^（3＋） extraction were investigated. Experimental results indicate that the optimum extraction conditions of Sm^（3＋） were obtained as that PC-88A concentration was 0.120 mol/L,and OAV was 1.00 in the dispersion phase,and pH value was 4.80 in the feed *** initial Sm^（3＋） concentration was 1.20×10^（-4） mol/L,the extraction percentage of Sm^（3＋） was up to 92.8%in 160 min.

关键词： Stripping dispersion hollow fiber liquid membrane 2-Ethyl hexyl phosphoric acid-mono-2-ethyl hexyl ester Samarium Dispersion phase Extraction flux Extraction rate

Trajectory prediction of ballistic missiles using Gaussian process error model

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第1期35卷 458-469页

作者： Ruiping ji Yan liang Linfeng XU Zhenwei WEI School of Automation Northwestern Polytcchnical UniversityXi'an 710129China Key Laboratory of Information Fusion Technology Ministry of EducationXi'an 710129China

Ballistic Missile Trajectory Prediction(BMTP)is critical to air defense *** Trajectory Prediction(TP)methods focus on the coast and reentry phases,in which the Ballistic Missile(BM)trajectories are modeled as ellipses or the state components are propagated by the dynamic integral equations on time *** contrast,the boost-phase TP is more challenging because there are many unknown forces acting on the BM in this *** tackle this difficult problem,a novel BMTP method by using Gaussian Processes(GPs)is proposed in this *** particular,the GP is employed to train the prediction error model of the boost-phase trajectory database,in which the error refers to the difference between the true BM state at the prediction moment and the integral extrapolation of the BM *** the final BMTP is a combination of the dynamic equation based numerical integration and the GP-based prediction *** the trained GP aims to capture the relationship between the numerical integration and the unknown error,the modified BM state prediction is closer to the true one compared with the original ***,the GP is able to output the uncertainty information of the TP,which is of great significance for determining the warning range centered on the predicted BM *** results show that the proposed method effectively improves the BMTP accuracy during the boost phase and provides reliable uncertainty estimation boundaries.

关键词： Ballistic missile Boost-phase trajectory State prediction Gaussian processes Uncertainty estimation