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PRINCIPLE TO CLOSED LOOP CONTROL DIFFERENTIAL CYLINDER WITH DOUBLE SPEED VARIABLE PUMPS AND SINGLE LOOP CONTROL SIGNAL 被引量:8
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作者 QuanLong NeubertT HelduserS 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2004年第1期85-88,共4页
To control the position of differential cylinder closed loop without usingany throttle elements, a flew idea that two speed variable pumps are used to compensate thenon-symmetric flow of differential cylinder is carri... To control the position of differential cylinder closed loop without usingany throttle elements, a flew idea that two speed variable pumps are used to compensate thenon-symmetric flow of differential cylinder is carried out. According to the leaking property of thesystem, a speed offset principle is also proposed to eliminate the cavitation and tension caused bythe leakage and condensation of oil, which makes the system be in the same state as a valvecontrolled circuit. This principle is explained theoretically and experimentally. Further therelationship that the pressures in cylinder chambers change with load and leakage, and therelationship between biasing speed and pre-load pressures in cylinder chambers are established. Theresearch has proved that the new system has similar technique features as those of controlled withservo valves, but due to the elimination of all the throttle lose the efficiency of system can beimproved greatly. 展开更多
关键词 Electro-hydraulic servo control Speed variable pump Differential cylindersystem
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Variation characteristics of aquifer parameters induced by groundwater source heat pump operation under variable flow 被引量:5
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作者 王松庆 张旭 《Journal of Central South University》 SCIE EI CAS 2011年第4期1272-1277,共6页
The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of buildin... The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of building air conditioning load were considered.The results,compared with the constant flow operation,indicate that the influence on the variations of porosity,hydraulic conductivity and confined water head is decreased by 48%,51% and 71%,respectively,under variable flow operation.The security of variable flow operation is superior to that of constant flow.It is also concluded that the climate region and function of the buildings are primary factors which affect the suitability of variable flow operation in GWSHP. 展开更多
关键词 groundwater source heat pump variation characteristic aquifer parameter variable flow
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Cavitation Detection in Variable Speed Pump by Analyzing the Acoustic and Vibration Spectrums 被引量:6
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作者 Ashraf Kotb Abdulaziz Morgan Abdulaziz 《Engineering(科研)》 2015年第10期706-716,共11页
Cavitation in pumps must be detected and prevented. The present work is an attempt to use the simultaneous measurements of vibration and sound for variable speed pump to detect cavitation. It is an attempt to declare ... Cavitation in pumps must be detected and prevented. The present work is an attempt to use the simultaneous measurements of vibration and sound for variable speed pump to detect cavitation. It is an attempt to declare the relationship between the vibration and sound for the same discharge of 780 L/h and NPSHA of 0.754 at variable speeds of 1476 rpm, 1644 rpm, 1932 rpm, 2190 rpm, 2466 rpm, and 2682 rpm. Results showed that: the occurrence of cavitation depends on the rotational speed, and the sound signals in both no cavitation and cavitation conditions appear in random manner. While, surveying the vibration and sound spectrums at the second, third, and fourth blade passing frequencies reveals no indications or phenomenon associated with the cavitation at variable speeds. It is recommended to survey the vibration spectra at the rotational and blade passing frequencies simultaneously as a detection unique method of cavitation. 展开更多
关键词 CENTRIFUGAL pump CAVITATION Vibration BLADE PASSING Frequency variable Speed
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Principle and Experimental Verification of Caudal-fin-type Piezoelectric-stack Pump with Variable-cross-section Oscillating Vibrator 被引量:12
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作者 HU Xiaoqi ZHANG Jianhui +3 位作者 HUANG Yi XIA Qixiao HUANG Weiqing ZHAO Chunsheng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第1期128-136,共9页
In the traditional flow-resistance-differential (FRD) type valve-less piezoelectric pump, the generated outflow and pressure are discontinuous because of the inherent periodicity and fluctuation of the pump. To overco... In the traditional flow-resistance-differential (FRD) type valve-less piezoelectric pump, the generated outflow and pressure are discontinuous because of the inherent periodicity and fluctuation of the pump. To overcome these drawbacks, utilizing the bending vibration of piezoelectric bimorph to drive fluid was conducted. However, our investigation on the current status of this piezoelectric bimorph pump shows that larger driving force and vibration amplitude are required for fluid pumping; the pumping can be realized through the centrifugal force; and the mechanism of fluid pumping is no longer further studied. Based on these cases, the paper designed a piezoelectric-stack pump with variable-cross-section oscillating (VCSO) vibrator by imitating the swing of the caudal-fin of tuna, and the pump is neither the rotating type nor the volumetric type according to the taxonomy. The interaction between the oscillating vibrator and the fluid parcel is firstly analyzed from the viewpoint of momentum conservation, and the analytical expression of pump flow rate is obtained. Then the modal and harmonic response analyses on the vibrator immerged in water are carried out. From the analyses the first two orders resonance frequencies are 832 Hz and 1 939 Hz, respectively, and the peak value of the tip amplitude is 0.6 mm. Laser Doppler vibrometer is used to measure both the frequency and vibration amplitude, and the determined first two orders resonance frequencies are 617 Hz and 1 356 Hz, respectively. The measured tip amplitude reaches to the peak value of 0.3 mm. At last, experimental measurement for the flow rates with different driving frequencies is conducted. The results show that the flow rate can reach 560 mL/min at 1 370 Hz when the pump runs under the backpressure of 30 mm water column. And the flow rate is as much as 560% of that of experiment results carried out by researchers from Brazil. The proposed pump innovates in both theory and taxonomy; in addition, the pump overcomes the drawbacks such as large flow fluctuation and low flow rate in the traditional FRD type pumps, which will help to broaden the application of the valve-less piezoelectric pump. 展开更多
关键词 caudal-fin-type variable-cross-section piezoelectric-stack valve-less pump
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Health status assessment of axial piston pump under variable speed 被引量:1
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作者 Guo Rui Li Hucheng +3 位作者 Zhao Zhiqian Zhang Rongbing Zhao Jingyi Gao Dianrong 《High Technology Letters》 EI CAS 2020年第3期315-322,共8页
The axial piston pump usually works under variable speed conditions.It is important to evaluate the health status of the axial piston pump under the variable speed condition.Aiming at the characteristic signals obtain... The axial piston pump usually works under variable speed conditions.It is important to evaluate the health status of the axial piston pump under the variable speed condition.Aiming at the characteristic signals obtained under different wear levels of the port plate,a feature signal extraction method under variable speed conditions is proposed.Firstly,the combination of complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)energy spectrum and fast spectral kurtosis principle is used to accurately extract the intrinsic mode function(IMF)component containing the sensitive information of the degraded feature.Then,the aspect ratio analysis method of the angle domain variational mode decomposition(VMD)is used to process the feature index containing the sensitive information of the degraded feature.In order to evaluate the health status of the axial piston pump under variable speed,the vibration reliability analysis method for axial piston pump based on Weibull proportional failure rate model is proposed.The experimental results show that the proposed method can accurately evaluate the health status of the axial piston pump. 展开更多
关键词 axial piston pump variable speed condition order ratio variational mode decomposition(VMD)in angle domain health status assessment
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A novel technology for control of variable speed pumped storage power plant 被引量:1
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作者 Seyed Mohammad Hassan Hosseini Mohammad Reza Semsar 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第8期2008-2023,共16页
Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control(DTFC) of a variable speed pumped storage power plant(V... Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control(DTFC) of a variable speed pumped storage power plant(VSPSP). By this method both torque and flux have been applied to control the VSPSP. The comparison between VSPSP's control strategies is studied. At the first, a wind turbine with the capacity 2.2 k W and DTFC control strategies simulated then a 250 MW VSPSP is simulated with all of its parts(including electrical, mechanical, hydraulic and its control system) by MATLAB software. In all of simulations, both converters including two-level voltage source converter(2LVSC) and three-level voltage source converter(3LVSC) are applied. The results of applying 2LVSC and 3LVSC are the rapid dynamic responses with better efficiency, reducing the total harmonic distortion(THD) and ripple of rotor torque and flux. 展开更多
关键词 direct torque and flux control(DTFC) two-level three-level voltage source converter(2LVSC&3LVSC) variable speed pumped storage power plant(VSPSP)
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Small and Mid-Size Pump-Turbines with Variable Speed
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作者 Jürgen Krenn Helmut Keck Manfred Sallaberger 《Energy and Power Engineering》 2013年第2期48-54,共7页
The stability of the grid is jeopardized with the large percentage of non-dispatchable renewables like wind power and also with increasing solar power. This creates various problems because these forms of energy are v... The stability of the grid is jeopardized with the large percentage of non-dispatchable renewables like wind power and also with increasing solar power. This creates various problems because these forms of energy are very volatile and difficult to predict. In most countries the in-feed of these sources must not be curtailed. In addition most of the renewables do not provide short circuit capacity and inertia in the same way as classical units and so further worsen the stability of the grid. The growing exploitation of wind and solar might be limited due to grid stability problems. In order to compensate those problems a large amount of reserve capacity is needed and therefore new technologies for electricity storage are required. Hydraulic pumped storage—the classical storage technology—has some disadvantages. These plants are in mountain regions often far away from wind farms. The distance to the wind farms mean additional loading for the already stressed grid and additional transmission losses. To compensate the very volatile wind energy, the pump input power should be varied continuously. This is so far only possible with variable speed units. Up to now double-fed asynchronous motor-generators are used which are rather expensive. In order to provide a solution for the described situation, ANDRITZ HYDRO has developed a new innovative concept of decentralized pump storage plants. Small standardized pump turbines are combined with a synchronous motor-generator and a full size converter which allows speed variation in pump and turbine mode over a wide range. These plants can be built locally close to wind farms and other sources to be balanced, allowing the increase of renewable energy without increasing the transmission line capacity. For the future smart grids this will be a key storage technology. This concept is reliable, innovative and more economic than other storage technologies. 展开更多
关键词 Grid Stability pump Storage variable SPEED Full SIZE Converter WIND Energy
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Design and research on a variable ballast system for deep-sea manned submersibles 被引量:7
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作者 邱中梁 《Journal of Marine Science and Application》 2008年第4期255-260,共6页
Variable ballast systems are necessary for manned submersibles to adjust their buoyancy.In this paper,the design of a variable ballast system for a manned submersible is described.The variable ballast system uses a su... Variable ballast systems are necessary for manned submersibles to adjust their buoyancy.In this paper,the design of a variable ballast system for a manned submersible is described.The variable ballast system uses a super high pressure hydraulic seawater system.A super high pressure seawater pump and a deep-sea brushless DC motor are used to pump seawater into or from the variable ballast tank,increasing or decreasing the weight of the manned submersible.A magnetostrictive linear displacement transducer can detect the seawater level in the variable ballast tank.Some seawater valves are used to control pumping direction and control on-off states.The design and testing procedure for the valves is described.Finally,the future development of variable ballast systems and seawater hydraulic systems is projected. 展开更多
关键词 DEEP-SEA manned submersible variable ballast system WEIGHT seawater pump seawater hydraulic system
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Research on DTC System with Variable Flux for Switched Reluctance Motor 被引量:2
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作者 Xianchao Zhao Aide.Xu Wen Zhang 《CES Transactions on Electrical Machines and Systems》 2017年第2期199-206,共8页
When switched reluctance motor(SRM)is in the status of the traditional direct torque control(DTC)system,due to the high saturation nonlinearity of the electromagnetic relationships of switched reluctance motors,the to... When switched reluctance motor(SRM)is in the status of the traditional direct torque control(DTC)system,due to the high saturation nonlinearity of the electromagnetic relationships of switched reluctance motors,the torque ripple and the stator phase current are larger.In order to resolve the above problems,through the analysis and deduction for SRM flux model and the influence of characteristics of flux and speed on torque ripple,this paper presents a variable-flux control strategy with the three closed-loop structure based on the critical flux supersaturated speed.And a DTC system of SRM with variable flux and three closed-loop is built up in Matlab/simulink.Moreover,the DSP hardware experiment platform based on the TMS320F2812 is established to validate the performance of the improved algorithm.The simulation and experimental results show that the new scheme has an obvious effect on torque ripple reduction,and the three-phase stator current is obviously reduced,which greatly reduces the stator winding copper consumption during the operation of SRM.Moreover,the improved system has good system stability. 展开更多
关键词 Critical flux supersaturated speed direct torque control switched reluctance motor three closed-loop variable flux
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Research on Energy Saving Technology of Load Sensitive Variable Steering System for Vehicles
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作者 LI Guangheng LU Yufeng 《International Journal of Plant Engineering and Management》 2020年第1期24-35,共12页
In view of the large energy loss problem in the traditional full hydraulic steering system,a scheme of replacing the ordinary pump with the priority valve with the load sensitive variable pump is proposed to make the ... In view of the large energy loss problem in the traditional full hydraulic steering system,a scheme of replacing the ordinary pump with the priority valve with the load sensitive variable pump is proposed to make the variable pump provide the corresponding flow rate according to the needs of the steering system to achieve the purpose of energy saving.Through the establishment of the system AMESim simulation model,the data comparison shows that the energy loss of the load sensitive variable steering system is significantly reduced relative to the traditional full hydraulic steering system. 展开更多
关键词 variable load pump steering system energy saving HYDRAULIC AMESIM SIMULATION
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An efficient FEM for pressure analysis of oil film in a piston pump 被引量:1
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作者 Tadeusz Zloto Arkadiusz Nagorka 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第1期49-61,共13页
The paper concerns numerical analysis of pressure distribution of an oil film on the valve plate in the variable height gap of an axial piston pump. The analysis employs the finite element method. For determination of... The paper concerns numerical analysis of pressure distribution of an oil film on the valve plate in the variable height gap of an axial piston pump. The analysis employs the finite element method. For determination of oil pressure variations in the gap, the Reynolds equation, commonly applied in the theory of lubrication, is applied. The equation is solved numerically with the use of self-developed program based on the finite element method. In order to obtain high accuracy of the results, an adaptive mesh refinement based on residual estimations of solution errors is applied. The calculation results are represented as dependent on the geometric and working parameters of the pump. 展开更多
关键词 pump variable height gap pressure distribution modeling adaptive finite element method
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Present status of pumped hydro storage operations to mitigate renewable energy fluctuations in Japan 被引量:1
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作者 Shota Ichimura Seiichiro Kimura 《Global Energy Interconnection》 2019年第5期424-429,共6页
This paper focuses on pumped hydro energy storage(PHES)plants’current operations after electricity system reforms and variable renewable energy(VRE)installations in Japan.PHES plants have historically been developed ... This paper focuses on pumped hydro energy storage(PHES)plants’current operations after electricity system reforms and variable renewable energy(VRE)installations in Japan.PHES plants have historically been developed to create electricity demand at night in order to operate base load power plants,such as nuclear power plants,in stable conditions.Therefore,many PHES plants are located midway between nuclear power plants and large demand areas.However,all nuclear power plants had to–at least temporarily–shut down after the Great East Japan Earthquake followed by a nuclear accident at Fukushima Daiichi in 2011,and renewable energy power plants have been deployed rapidly after the introduction of a feed-in-tariff(FIT)scheme.Therefore,PHES plants are being used to mitigate fluctuations of VRE,especially in areas where renewable energy has been significantly installed.The daily highest capacity ratio of PHES plants in Kyushu area has recorded three times higher than it in the other areas where the past operating mode is still conducted.But those operations on PHES plants are simply followed as a dispatch rule of the Organization for Crossregional Coordination of Transmission Operators(OCCTO),market-based operations have not been conducted enough yet.The market design shall be changed to harmonize VRE installation and PHES plants’operations are necessary to make the transition from the past operating mode of PHES plants across Japan. 展开更多
关键词 pumpED hydro ENERGY STORAGE PLANT Nuclear power PLANT variable RENEWABLE ENERGY Solar photovoltaic Marketdesign
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Pressure pulsation in stages of electric submersible pump at shut-off under various speeds 被引量:1
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作者 DHANASEKARAN Arumugam KUMARASWAMY Sivasailam 《排灌机械工程学报》 EI CSCD 北大核心 2020年第7期649-657,共9页
Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the li... Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the life and performance of its system. The objective of this study was to experimentally investigate the characteristics of pressure pulsation which were generated at various stages of a multistage electric submersible pump during closed valve operation at different speeds. An electric submersible pump with five stages was selected for conducting experiments. A variable frequency drive( VFD)was used to operate the electric submersible pump at five different speed settings from 40 to 60 Hz. Piezoresistive pressure transducers were mounted at each stage of the electric submersible pump to capture the unsteady pressure signals. At each speed setting,the electric submersible pump was operated at the shut-off condition and the signals of unsteady pressure from all the five stages were captured. A fast fourier transformation( FFT) was carried out on the pressure signals to convert into frequency domain.From the spectra of pressure pulsation signals,the characteristics of pressure pulsation are obtained for each stage and for various speed settings which were then used to understand its variation with speed and stages. 展开更多
关键词 electric submersible pump shut-off STAGE pressure pulsation variable frequency
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Successful use of closed-loop allostatic neurotechnology for post-traumatic stress symptoms in military personnel: self-reported and autonomic improvements 被引量:1
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作者 Catherine L.Tegeler Lee Gerdes +4 位作者 Hossam A.Shaltout Jared F.Cook Sean L.Simpson Sung W.Lee Charles H.Tegeler 《Military Medical Research》 SCIE CAS 2018年第1期1-12,共12页
Background:Military-related post-traumatic stress(PTS)is associated with numerous symptom clusters and diminished autonomic cardiovascular regulation.Highresolution,relational,resonance-based,electroencephalic mirrori... Background:Military-related post-traumatic stress(PTS)is associated with numerous symptom clusters and diminished autonomic cardiovascular regulation.Highresolution,relational,resonance-based,electroencephalic mirroringis a noninvasive,closed-loop,allostatic,acoustic stimulation neurotechnology that produces realtime translation of dominant brain frequencies into audible tones of variable pitch and timing to support the autocalibration of neural oscillations.We report clinical,autonomic,and functional effects after the use offor symptoms of military-related PTS.Methods:Eighteen service members or recent veterans(15 active-duty,3 veterans,most from special operations,1 female),with a mean age of 40.9(SD=6.9)years and symptoms of PTS lasting from 1 to 25 years,undertook19.5(SD=1.1)sessions over 12 days.Inventories for symptoms of PTS(Posttraumatic Stress Disorder Checklist–Military version,PCL-M),insomnia(Insomnia Severity Index,ISI),depression(Center for Epidemiologic Studies Depression Scale,CES-D),and anxiety(Generalized Anxiety Disorder 7-item scale,GAD-7)were collected before(Visit1,V1),immediately after(Visit2,V2),and at 1 month(Visit3,V3),3(Visit4,V4),and 6(Visit5,V5)months after intervention completion.Other measures only taken at V1 and V2 included blood pressure and heart rate recordings to analyze heart rate variability(HRV)and baroreflex sensitivity(BRS),functional performance(reaction and grip strength)testing,blood and saliva for biomarkers of stress and inflammation,and blood for epigenetic testing.Paired t-tests,Wilcoxon signed-rank tests,and a repeated-measures ANOVA were performed.Results:Clinically relevant,significant reductions in all symptom scores were observed at V2,with durability through V5.There were significant improvements in multiple measures of HRV and BRS[Standard deviation of the normal beat to normal beat interval(SDNN),root mean square of the successive differences(rMSSD),high frequency(HF),low frequency(LF),and total power,HF alpha,sequence all,and systolic,diastolic and mean arterial pressure]as well as reaction testing.Trends were seen for improved grip strength and a reduction in C-Reactive Protein(CRP),Angiotensin II to Angiotensin 1–7 ratio and Interleukin-10,with no change in DNA n-methylation.There were no dropouts or adverse events reported. Conclusion:Service members or veterans showed reductions in symptomatology of PTS,insomnia,depressive mood,and anxiety that were durable through 6 months after the use of a closed-loop allostatic neurotechnology for the autocalibration of neural oscillations.This study is the first to report increased HRV or BRS after the use of an intervention for service members or veterans with PTS.Ongoing investigations are strongly warranted.Trial registration:NCT03230890,retrospectively registered July 25,2017. 展开更多
关键词 NEUROTECHNOLOGY ALLOSTASIS AUTONOMIC Heart rate variability Baroreflex sensitivity closed-loop Acoustic stimulation Military Post-traumatic stress disorder HIRREM
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Discrete Optimization on Unsteady Pressure Fluctuation of a Centrifugal Pump Using ANN and Modified GA 被引量:1
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作者 Wenjie Wang Qifan Deng +2 位作者 Ji Pei Jinwei Chen Xingcheng Gan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2023年第4期242-256,共15页
Pressure fluctuation due to rotor-stator interaction in turbomachinery is unavoidable,inducing strong vibration in the equipment and shortening its lifecycle.The investigation of optimization methods for an industrial... Pressure fluctuation due to rotor-stator interaction in turbomachinery is unavoidable,inducing strong vibration in the equipment and shortening its lifecycle.The investigation of optimization methods for an industrial centrifugal pump was carried out to reduce the intensity of pressure fluctuation to extend the lifecycle of these devices.Considering the time-consuming transient simulation of unsteady pressure,a novel optimization strategy was proposed by discretizing design variables and genetic algorithm.Four highly related design parameters were chosen,and 40 transient sample cases were generated and simulated using an automatic program.70%of them were used for training the surrogate model,and the others were for verifying the accuracy of the surrogate model.Furthermore,a modified discrete genetic algorithm(MDGA)was proposed to reduce the optimization cost owing to transient numerical simulation.For the benchmark test,the proposed MDGA showed a great advantage over the original genetic algorithm regarding searching speed and effectively dealt with the discrete variables by dramatically increasing the convergence rate.After optimization,the performance and stability of the inline pump were improved.The efficiency increased by more than 2.2%,and the pressure fluctuation intensity decreased by more than 20%under design condition.This research proposed an optimization method for reducing discrete transient characteristics in centrifugal pumps. 展开更多
关键词 Centrifugal pump Unsteady performance optimization Discrete design variable Discrete genetic algorithm
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基于PumpLinx的变量燃料泵流动特性仿真研究
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作者 王凯 孙涛 +3 位作者 史小锋 伊寅 李永东 黄艳芬 《鱼雷技术》 2015年第6期444-448,共5页
为了研究鱼雷变量燃料泵的流动特性,文中提出了一种使用标准模版实现静缸式柱塞泵的研究方法,通过3D建模软件UG与计算流体力学(CFD)仿真软件Pump Linx完成对柱塞泵的仿真。在此基础上,进一步对泵的流量、压力和空化进行了仿真和分析。... 为了研究鱼雷变量燃料泵的流动特性,文中提出了一种使用标准模版实现静缸式柱塞泵的研究方法,通过3D建模软件UG与计算流体力学(CFD)仿真软件Pump Linx完成对柱塞泵的仿真。在此基础上,进一步对泵的流量、压力和空化进行了仿真和分析。仿真结果表明,变量泵不会产生空化现象,但流量脉动较大且高低压过渡不平稳,这些结论对变量泵的改进设计有一定的参考价值。 展开更多
关键词 鱼雷 变量燃料泵 静缸式
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Closed-loop identification of systems using hybrid Box–Jenkins structure and its application to PID tuning 被引量:1
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作者 李全善 李大字 曹柳林 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第12期1997-2004,共8页
The paper describes a closed-loop system identification procedure for hybrid continuous-time Box–Jenkins models and demonstrates how it can be used for IMC based PID controller tuning. An instrumental variable algori... The paper describes a closed-loop system identification procedure for hybrid continuous-time Box–Jenkins models and demonstrates how it can be used for IMC based PID controller tuning. An instrumental variable algorithm is used to identify hybrid continuous-time transfer function models of the Box–Jenkins form from discretetime prefiltered data, where the process model is a continuous-time transfer function, while the noise is represented as a discrete-time ARMA process. A novel penalized maximum-likelihood approach is used for estimating the discrete-time ARMA process and a circulatory noise elimination identification method is employed to estimate process model. The input–output data of a process are affected by additive circulatory noise in a closedloop. The noise-free input–output data of the process are obtained using the proposed method by removing these circulatory noise components. The process model can be achieved by using instrumental variable estimation method with prefiltered noise-free input–output data. The performance of the proposed hybrid parameter estimation scheme is evaluated by the Monte Carlo simulation analysis. Simulation results illustrate the efficacy of the proposed procedure. The methodology has been successfully applied in tuning of IMC based flow controller and a practical application demonstrates the applicability of the algorithm. 展开更多
关键词 Hybrid Box–Jenkins models ARMA models Instrumental variable closed-loop identification PID tuning
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Prospect of new pumped-storage power station 被引量:4
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作者 Jingyan Li Chuanbao Yi Sujie Gao 《Global Energy Interconnection》 2019年第3期235-243,共9页
In this paper, a new type of pumped-storage power station with faster response speed, wider regulation range, and better stability is proposed. The operational flexible of the traditional pumped-storage power station ... In this paper, a new type of pumped-storage power station with faster response speed, wider regulation range, and better stability is proposed. The operational flexible of the traditional pumped-storage power station can be improved with variable-speed pumped-storage tech no logy. Combined with chemical en ergy storage, the failure to achieve sec on d-order response speed and the insufficient safety and reliability of pumped-storage power units could be solved. With the better solar en ergy and site resources, the in teg rated performance can be improved by an optical storage system in stalled in future pumped-storage stations. Through the characteristics analysis of the new type of pumped-storage power station, three types of optimal station locations are proposed, namely, the load concentration area, new energy concentration area, and ultrahigh- voltage direct current receiver area. Taking the new pumped-storage power station as an example, the advantages of multi-energy cooperation and joint operation are analyzed. It can be predicted that the frequency and load regulation of the power grid will be more flexible, and the service capacity to the main power grid will be much stronger in the future. 展开更多
关键词 pumped-storage POWER STATION variable-speed pumped-storage technology CHEMICAL ENERGY STORAGE Solarenergy STORAGE system
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Feasibility Analysis of Back-Pressure Steam Feeding Water Pump for Direct Air-Cooled Unit 被引量:1
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作者 Zhao Xiaodong Wang Meng +2 位作者 Du Xiaoze Yang Lijun Yang Yongping 《Electricity》 2013年第1期31-35,共5页
As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introd... As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introduces a new design of for steam feeding the water pump of an air-cooled unit using the back-pressure steam turbine as the prime motor. Using variable condition analysis on a 600 MW direct air-cooled unit, and with consideration of the effect on the ambient conditions, the feasibility, economy, and adaptability of the design are verified. 展开更多
关键词 air-cooled back-pressure steam turbine steam feed water pump variable condition
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Numerical simulation of transient flow performance during different periods in centrifugal pumpNumerical simulation of transient flow performance during different periods in centrifugal pump
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作者 HUANG Si ZHANG Jie +1 位作者 ZHANG Xuejiao SU Xianghui 《排灌机械工程学报》 EI CSCD 北大核心 2016年第9期737-741,共5页
The instantaneous variations of the hydraulic characteristics take place in centrifugal pumps during their start-up,shutdown and other variable speed operations.In this paper,the variable speed method was proposed to ... The instantaneous variations of the hydraulic characteristics take place in centrifugal pumps during their start-up,shutdown and other variable speed operations.In this paper,the variable speed method was proposed to simulate the transient internal flow field and the external performance of the pump during starting and stopping periods.The terms of accelerations due to variable speeds in the flow governing equations were analyzed in a multiple reference of frame(MRF).A transient CFD simulation was performed for a typical centrifugal pump by using ANSYS-CFX with the standard k-εturbulence model.The entire simulation process was composed of four stages:start-up,normal run,shutdown and post-shutdown.The function of rotating speed with regard to time was set by CEL language directly into the impeller domain in the pre-processor of the software to conduct variable speed simulation.The variations of the flow field in the centrifugal pump were obtained from the transient simulation.The changing laws of flow rate,head and other performance parameters over time were also analyzed and summarized. 展开更多
关键词 centrifugal pump variable speed method starting and STOPPING PERIODS transient flow field numerical simulation
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