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
To a kind of centrifugal water chiller with R22 and about 1 745 kW of cooling capacity,a heat exchanger was added between the outlet of compressor and original condenser to get part of or all the condensing heat.Conde...To a kind of centrifugal water chiller with R22 and about 1 745 kW of cooling capacity,a heat exchanger was added between the outlet of compressor and original condenser to get part of or all the condensing heat.Condensing heat can be recovered by compound condensing method,which adopts air-cooling model +water-cooling model or water-cooling model +water-cooling model at the condensing side of the system.By exergy analysis and experiment research on compound condensing heat recovery of centrifugal chiller,the results are obtained that the capability of the whole system increases,the energy efficiency ratio(EER)becomes 3.2～5.0 from 2.2～3.4,which implies the EER increases about 1.0～1.5,the exergy efficiency increases about 10%,and the chiller runs more stably after reformation.展开更多
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
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.
文摘To a kind of centrifugal water chiller with R22 and about 1 745 kW of cooling capacity,a heat exchanger was added between the outlet of compressor and original condenser to get part of or all the condensing heat.Condensing heat can be recovered by compound condensing method,which adopts air-cooling model +water-cooling model or water-cooling model +water-cooling model at the condensing side of the system.By exergy analysis and experiment research on compound condensing heat recovery of centrifugal chiller,the results are obtained that the capability of the whole system increases,the energy efficiency ratio(EER)becomes 3.2～5.0 from 2.2～3.4,which implies the EER increases about 1.0～1.5,the exergy efficiency increases about 10%,and the chiller runs more stably after reformation.
文摘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.
