Investigations regarding the relation of noise performance for centrifugal pump operating in pump and turbine modes continue to be inadequate.This paper presents a series of comparisons of flow-induced noise for both ...Investigations regarding the relation of noise performance for centrifugal pump operating in pump and turbine modes continue to be inadequate.This paper presents a series of comparisons of flow-induced noise for both operation modes.The interior flow-borne noise and structure modal were verified through experiments.The flow-borne noise was calculated by the acoustic boundary element method(ABEM),and the flow-induced structure noise was obtained by the coupled acoustic boundary element method(ABEM)/structure finite element method(SFEM).The results show that in pump mode,the pressure fluctuation in the volute is comparable to that in the outlet pipe,but in turbine mode,the pressure fluctuation in the impeller is comparable to that in the draft tube.The main frequency of interior flow-borne noise lies at blade passing frequency(BPF)and it shifts to the 9th BPF for interior flow-induced structure noise.The peak values at horizontal plane appear at the 5th BPF,and at axial plane,they get the highest sound pressure level(SPL)at the 8th BPF.Comparing with interior noise,the SPL of exterior flow-induced structure noise is incredibly small.At the 5th BPF,the pump body,cover and suspension show higher SPL in both modes.The outer walls of turbine generate relatively larger SPL than those of the pump.展开更多
Thyroid stimulating hormone receptor（TSHR） is thought to be a significant candidate for genetic susceptibility to Graves＇ disease（GD）.However,the association between TSHR gene polymorphism and the risk of GD rema...Thyroid stimulating hormone receptor（TSHR） is thought to be a significant candidate for genetic susceptibility to Graves＇ disease（GD）.However,the association between TSHR gene polymorphism and the risk of GD remains controversial.In this study,we investigated the relationship between the two conditions by meta-analysis.We searched all relevant case-control studies in PubMed,Web of Science,CNKI and Wanfang for literature available until May2015,and chose studies on two single nucleotide polymorphisms（SNPs）：rs 179247 and rsl2101255,within TSHR intron-1.Bias of heterogeneity test among studies was determined by the fixed or random effect pooled measure,and publication bias was examined by modified Begg＇s and Egger＇s test.Eight eligible studies with 15 outcomes were involved in this meta-analysis,including 6,976 GD cases and 7,089 controls from China,Japan,Poland,UK and Brazil.Pooled odds ratios（ORs） for allelic comparisons showed that both TSHR rsl79247A/G and rsl2101255T/C polymorphism had significant association with GD（OR=1.422,95%CI=1.353—1.495,P〈0.001,P_（heterogeneity）=0.448;OR= 1.502,95%CI：1.410-1.600,P〈0.001,P_（heterogeneity）=0.642）,and the associations were the same under dominant,recessive and co-dominant models.In subgroup analyses,the conclusions are also consistent with all those in Asian,European and South America subgroups（P〈0.001）.Our meta-analysis revealed a significant association between TSHR rsl79247A/G and rsl2101255T/C polymorphism with GD in five different populations from Asia,Europe and South America.Further studies are needed in other ethnic backgrounds to independently confirm our findings.展开更多
In order to reveal the regularity of unsteady flow of centrifugal pump under different cavitation stages,a visual closed test-bed is built to collect signals such as the distribution of cavitation bubbles at the impel...In order to reveal the regularity of unsteady flow of centrifugal pump under different cavitation stages,a visual closed test-bed is built to collect signals such as the distribution of cavitation bubbles at the impeller inlet and external characteristics,etc.in the process of cavitation of centrifugal pumps.Combined with the shape and distribution of bubbles captured by high-speed photography,the cavitation stage of the centrifugal pump is divided.In addition,the variation of vorticity distribution,pressure pulsation and radial force of centrifugal pump under different cavitation stages are studied using the standard κ-ε turbulence model and the Kunz cavitation model.Main contributions are as follows:The cavitation bubbles can absorb the energy of vortex core to a certain extent and increase the volume of vortex core.Cavitation bubbles can also block the flow-path and induce the distortion of the internal flow field,resulting in unstable pressure waves that cause a significant increase in pressure pulsation rate.Besides,with the development of cavitation,the radial force on the impeller tends to remain invariable first and then decrease,and trajectory of the radial force changes from closed to open.展开更多
The modifications of impeller may show diverse impact on centrifugal pump operating in pump and turbine modes.To clarify this problem,the hydraulic performance of a low specific speed centrifugal pump operating in bot...The modifications of impeller may show diverse impact on centrifugal pump operating in pump and turbine modes.To clarify this problem,the hydraulic performance of a low specific speed centrifugal pump operating in both modes was firstly obtained by CFD method and verified by experiment.Then,based on the single-factor design method,a series of calculations have been conducted to identify the effects of impeller geometry parameters on the hydraulic performance in different modes.The variations of head,shaft power and hydraulic efficiency curves with different impeller parameters were explored.It is found that compared with turbine,the pump shows a more obvious variation of head.The outlet angle has positive impact both on the head consumed by pump or generated by turbine.The change of turbine shaft power is apparently smaller than that of pump for different impeller geometry parameters.Only the outlet width somewhat changes the turbine shaft power.The hydraulic efficiency in both modes shows different variation under different impeller geometric parameters,while the hydraulic efficiency of both modes is reduced with the outlet angle increasing.Meanwhile,the response amount of hydraulic efficiency caused by certain change of impeller parameters was estimated by sensitivity analysis method.It is found that only the appropriate blade number and outlet width can improve the hydraulic performance both in pump and turbine modes.Eventually,the hydraulic loss,skin friction loss and theoretical analysis were performed to explore the reason of hydraulic performance variation due to different impeller parameters.The change of slip factor,impeller inlet area,impeller outlet area or hydraulic loss results in the change of hydraulic performance in both modes.The results can be useful for hydraulic performance improvement for both pump and turbine modes through impeller geometry modification.展开更多
In order to study the variation of brake torque,vibration,pressure fluctuation,exterior noise and internal flow for a hydraulic retarder with different inclination angles and liquid-filled amount,a bench-scale hydraul...In order to study the variation of brake torque,vibration,pressure fluctuation,exterior noise and internal flow for a hydraulic retarder with different inclination angles and liquid-filled amount,a bench-scale hydraulic retarder was built.The INV3020 data collection system was used for the synchronous acquisition of brake torque,vibration,pressure fluctuation and exterior noise signals.Experiments were performed with different inclination angles(90°and 75°)and six liquid-filled amount(50 vol%,60 vol%,70 vol%,80 vol%,90vol%and 100 vol%).The torque-volume ratio was proposed to accurately analyze the influence of inclination angle on the liquid volume in stator and rotor and the brake performance.Mixture multiphase flow model was employed to capture the volume and velocity distribution.The research shows that the brake performance improves and the vibration increases with the decrease of inclination angle and the increase of liquid-filled amount.The pressure fluctuation increases as the liquid-filled amount increases,while the lower inclination angle effectively lowers the pressure fluctuation amplitude.The sound pressure level trends upward with increasing liquid-filled amount,and the lower inclination angle can effectively reduce the noise.The volume distribution of the liquid phase under different liquid-filled amount is basically consistent.The lower inclination angle can induce more vortexes.展开更多
基金Project (51509111) supported by the National Natural Science Foundation of ChinaProject (2017M611721) supported by the China Postdoctoral Science Foundation+4 种基金Project (BY2016072-01) supported by the Association Innovation Fund of Production,Learning,and Research,ChinaProjects (GY2017001,GY2018025) supported by Zhenjiang Key Research and Development Plan,ChinaProjects (szjj2015-017,szjj2017-094) supported by the Open Research Subject of Key Laboratory of Fluid and Power Machinery,ChinaProject (GK201614) supported by Sichuan Provincial Key Lab of Process Equipment and Control,ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),China
文摘Investigations regarding the relation of noise performance for centrifugal pump operating in pump and turbine modes continue to be inadequate.This paper presents a series of comparisons of flow-induced noise for both operation modes.The interior flow-borne noise and structure modal were verified through experiments.The flow-borne noise was calculated by the acoustic boundary element method(ABEM),and the flow-induced structure noise was obtained by the coupled acoustic boundary element method(ABEM)/structure finite element method(SFEM).The results show that in pump mode,the pressure fluctuation in the volute is comparable to that in the outlet pipe,but in turbine mode,the pressure fluctuation in the impeller is comparable to that in the draft tube.The main frequency of interior flow-borne noise lies at blade passing frequency(BPF)and it shifts to the 9th BPF for interior flow-induced structure noise.The peak values at horizontal plane appear at the 5th BPF,and at axial plane,they get the highest sound pressure level(SPL)at the 8th BPF.Comparing with interior noise,the SPL of exterior flow-induced structure noise is incredibly small.At the 5th BPF,the pump body,cover and suspension show higher SPL in both modes.The outer walls of turbine generate relatively larger SPL than those of the pump.
基金supported by grants from the National Natural Science Foundation of China(Grant No.81102032)
文摘Thyroid stimulating hormone receptor（TSHR） is thought to be a significant candidate for genetic susceptibility to Graves＇ disease（GD）.However,the association between TSHR gene polymorphism and the risk of GD remains controversial.In this study,we investigated the relationship between the two conditions by meta-analysis.We searched all relevant case-control studies in PubMed,Web of Science,CNKI and Wanfang for literature available until May2015,and chose studies on two single nucleotide polymorphisms（SNPs）：rs 179247 and rsl2101255,within TSHR intron-1.Bias of heterogeneity test among studies was determined by the fixed or random effect pooled measure,and publication bias was examined by modified Begg＇s and Egger＇s test.Eight eligible studies with 15 outcomes were involved in this meta-analysis,including 6,976 GD cases and 7,089 controls from China,Japan,Poland,UK and Brazil.Pooled odds ratios（ORs） for allelic comparisons showed that both TSHR rsl79247A/G and rsl2101255T/C polymorphism had significant association with GD（OR=1.422,95%CI=1.353—1.495,P〈0.001,P_（heterogeneity）=0.448;OR= 1.502,95%CI：1.410-1.600,P〈0.001,P_（heterogeneity）=0.642）,and the associations were the same under dominant,recessive and co-dominant models.In subgroup analyses,the conclusions are also consistent with all those in Asian,European and South America subgroups（P〈0.001）.Our meta-analysis revealed a significant association between TSHR rsl79247A/G and rsl2101255T/C polymorphism with GD in five different populations from Asia,Europe and South America.Further studies are needed in other ethnic backgrounds to independently confirm our findings.
基金supported by the National Key Research and Development Program of China(2017YFC0804107)National Natural Science Foundation of China(No.51879122,51779106,51509111)+6 种基金the association innovation fund of production,learning,and research(BY2016072-01)Zhenjiang key research and development plan(GY2017001,GY2018025)the Open Research Subject of Key Laboratory of Fluid and Power Machinery,Ministry of Education,Xihua University(szjj2015-017,szjj2017-094,szjj2016-068)Sichuan Provincial Key Lab of Process Equipment and Control(GK201614,GK201816)the Advanced Talent Foundation of Jiangsu University(15JDG052)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Jiangsu top six talent summit project(GDZB-017)
文摘In order to reveal the regularity of unsteady flow of centrifugal pump under different cavitation stages,a visual closed test-bed is built to collect signals such as the distribution of cavitation bubbles at the impeller inlet and external characteristics,etc.in the process of cavitation of centrifugal pumps.Combined with the shape and distribution of bubbles captured by high-speed photography,the cavitation stage of the centrifugal pump is divided.In addition,the variation of vorticity distribution,pressure pulsation and radial force of centrifugal pump under different cavitation stages are studied using the standard κ-ε turbulence model and the Kunz cavitation model.Main contributions are as follows:The cavitation bubbles can absorb the energy of vortex core to a certain extent and increase the volume of vortex core.Cavitation bubbles can also block the flow-path and induce the distortion of the internal flow field,resulting in unstable pressure waves that cause a significant increase in pressure pulsation rate.Besides,with the development of cavitation,the radial force on the impeller tends to remain invariable first and then decrease,and trajectory of the radial force changes from closed to open.
基金supported by National Key Research and Development Program of China(Grant No.2016YFB0200901,2017YFC0804107)National Natural Science Foundation of China(No.51879122,51509111,51779106)+5 种基金Zhenjiang key research and development plan(GY2017001,GY2018025)the Open Research Subject of Key Laboratory of Fluid and Power Machinery,Ministry of Education,Xihua University(szjj2015-017,szjj2017-094,szjj2016-068)Sichuan Provincial Key Lab of Process Equipment and Control(GK201614,GK201816)Young Talent Incubation Program of Jiangsu Universitya project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Jiangsu top six talent summit project(GDZB-017)。
文摘The modifications of impeller may show diverse impact on centrifugal pump operating in pump and turbine modes.To clarify this problem,the hydraulic performance of a low specific speed centrifugal pump operating in both modes was firstly obtained by CFD method and verified by experiment.Then,based on the single-factor design method,a series of calculations have been conducted to identify the effects of impeller geometry parameters on the hydraulic performance in different modes.The variations of head,shaft power and hydraulic efficiency curves with different impeller parameters were explored.It is found that compared with turbine,the pump shows a more obvious variation of head.The outlet angle has positive impact both on the head consumed by pump or generated by turbine.The change of turbine shaft power is apparently smaller than that of pump for different impeller geometry parameters.Only the outlet width somewhat changes the turbine shaft power.The hydraulic efficiency in both modes shows different variation under different impeller geometric parameters,while the hydraulic efficiency of both modes is reduced with the outlet angle increasing.Meanwhile,the response amount of hydraulic efficiency caused by certain change of impeller parameters was estimated by sensitivity analysis method.It is found that only the appropriate blade number and outlet width can improve the hydraulic performance both in pump and turbine modes.Eventually,the hydraulic loss,skin friction loss and theoretical analysis were performed to explore the reason of hydraulic performance variation due to different impeller parameters.The change of slip factor,impeller inlet area,impeller outlet area or hydraulic loss results in the change of hydraulic performance in both modes.The results can be useful for hydraulic performance improvement for both pump and turbine modes through impeller geometry modification.
基金supported by National Natural Science Foundation of China(No.51879122,51579117,51779106)National Key Research and Development Program of China(Grant No.2016YFB0200901,2017YFC0804107)+5 种基金Zhenjiang key research and development plan(GY2017001,GY2018025)the Open Research Subject of Key Laboratory of Fluid and Power Machinery,Ministry of Education,Xihua University(szjj2017-094,szjj2016-068)Sichuan Provincial Key Lab of Process Equipment and Control(GK201614,GK201816)Jiangsu University Young Talent training Program-Outstanding Young backbone TeacherProgram Development of Jiangsu Higher Education Institutions(PAPD)Jiangsu top six talent summit project(GDZB-017)。
文摘In order to study the variation of brake torque,vibration,pressure fluctuation,exterior noise and internal flow for a hydraulic retarder with different inclination angles and liquid-filled amount,a bench-scale hydraulic retarder was built.The INV3020 data collection system was used for the synchronous acquisition of brake torque,vibration,pressure fluctuation and exterior noise signals.Experiments were performed with different inclination angles(90°and 75°)and six liquid-filled amount(50 vol%,60 vol%,70 vol%,80 vol%,90vol%and 100 vol%).The torque-volume ratio was proposed to accurately analyze the influence of inclination angle on the liquid volume in stator and rotor and the brake performance.Mixture multiphase flow model was employed to capture the volume and velocity distribution.The research shows that the brake performance improves and the vibration increases with the decrease of inclination angle and the increase of liquid-filled amount.The pressure fluctuation increases as the liquid-filled amount increases,while the lower inclination angle effectively lowers the pressure fluctuation amplitude.The sound pressure level trends upward with increasing liquid-filled amount,and the lower inclination angle can effectively reduce the noise.The volume distribution of the liquid phase under different liquid-filled amount is basically consistent.The lower inclination angle can induce more vortexes.
