A unit pump test bench is developed on an in-line pump test platform. The bench is composed of pump adapting assembly, fuel supply subsystem, lubricating subsystem and a control unit. A crank angle domain injection co...A unit pump test bench is developed on an in-line pump test platform. The bench is composed of pump adapting assembly, fuel supply subsystem, lubricating subsystem and a control unit. A crank angle domain injection control method is given out and the control accuracy can be 0.1° crank degree. The bench can test both mechanical unit pump and electronic unit pump. A test model-PLD12 electronic unit pump is tested. Full pump delivery map and some influence factors test is done. Experimental results show that the injection quantity is linear with the delivery angle. The quantity change rate is 15% when fuel temperature increases 30 ℃. The delivery quantity per cycle increases 30 mg at 28 V drive voltage. The average delivery difference for two same type pumps is 5 %. Test results show that the bench can be used for unit pump verification.展开更多
Pumping test of a water table aquifer is carried out to estimate the aquifer parameters, the obtained data were analysed through the solution of both Neuman(1975) and Jacob(1946) methods through AQTESOLV and Spreadshe...Pumping test of a water table aquifer is carried out to estimate the aquifer parameters, the obtained data were analysed through the solution of both Neuman(1975) and Jacob(1946) methods through AQTESOLV and Spreadsheet programs, the results of each methods are compared to evaluate the applicability and accuracy of the solution theoretically and practically. In the paper an example is presented, which is conducted for a constant rate pumping test from Ohio, in Fairborn(near Dayton), and it supplied by S.E. Norris(U.S. Geological Survey, Columbus, Ohio). The main objective of this study is to introduce both program and the way of the applications, and compare the results and the hand on of both programs in the field.展开更多
The origin and movement of groundwater are the fundamental questions that address both the temporal and spatial aspects of ground water run and water supply related issues in hydrological systems.As groundwater flows ...The origin and movement of groundwater are the fundamental questions that address both the temporal and spatial aspects of ground water run and water supply related issues in hydrological systems.As groundwater flows through an aquifer,its composition and temperature may variation dependent on the aquifer condition through which it flows.Thus,hydrologic investigations can also provide useful information about the subsurface geology of a region.But because such studies investigate processes that follow under the Earth's shallow,obtaining the information necessary to answer these questions is not continuously easy.Springs,which discharge groundwater table directly,afford to study subsurface hydrogeological processes.The present study of estimation of aquifer factors such as transmissivity(T)and storativity(S)are vital for the evaluation of groundwater resources.There are several methods to estimate the accurate aquifer parameters(i.e.hydrograph analysis,pumping test,etc.).In initial days,these parameters are projected either by means of in-situ test or execution test on aquifer well samples carried in the laboratory.The simultaneous information on the hydraulic behavior of the well(borehole)that provides on this method,the reservoir and the reservoir boundaries,are important for efficient aquifer and well data management and analysis.The most common in-situ test is pumping test performed on wells,which involves the measurement of the fall and increase of groundwater level with respect to time.The alteration in groundwater level(drawdown/recovery)is caused due to pumping of water from the well.Theis(1935)was first to propose method to evaluate aquifer parameters from the pumping test on a bore well in a confined aquifer.It is essential to know the transmissivity(T=Kb,where b is the aquifer thickness;pumping flow rate,Q=TW(dh/dl)flow through an aquifer)and storativity(confined aquifer:S=bS_s,unconfined:S=S_y),for the characterization of the aquifer parameters in an unknown area so as to predict the rate of drawdown of the groundwater table/potentiometric surface throughout the pumping test of an aquifer.The determination of aquifer's parameters is an important basis for groundwater resources evaluation,numerical simulation,development and protection as well as scientific management.For determining aquifer's parameters,pumping test is a main method.A case study shows that these techniques have been fast speed and high correctness.The results of parameter's determination are optimized so that it has important applied value for scientific research and geology engineering preparation.展开更多
The current research about the flow ripple of axial piston pump mainly focuses on the effect of the structure of parts on the flow ripple. Therein, the structure of parts are usually designed and optimized at rated wo...The current research about the flow ripple of axial piston pump mainly focuses on the effect of the structure of parts on the flow ripple. Therein, the structure of parts are usually designed and optimized at rated working conditions. However, the pump usually has to work in large-scale and time-variant working conditions. Therefore, the flow ripple characteristics of pump and analysis for its test accuracy with respect to variant steady-state conditions and transient conditions in a wide range of operating parameters are focused in this paper. First, a simulation model has been constructed, which takes the kinematics of oil film within friction pairs into account for higher accuracy. Afterwards, a test bed which adopts Secondary Source Method is built to verify the model. The simulation and tests results show that the angular position of the piston, corresponding to the position where the peak flow ripple is produced, varies with the different pressure. The pulsating amplitude and pulsation rate of flow ripple increase with the rise of pressure and the variation rate of pressure. For the pump working at a constant speed, the flow pulsation rate decreases dramatically with the increasing speed when the speed is less than 27.78% of the maximum speed, subsequently presents a small decrease tendency with the speed further increasing. With the rise of the variation rate of speed, the pulsating amplitude and pulsation rate of flow ripple increase. As the swash plate angle augments, the pulsating amplitude of flow ripple increases, nevertheless the flow pulsation rate decreases. In contrast with the effect of the variation of pressure, the test accuracy of flow ripple is more sensitive to the variation of speed. It makes the test accuracy above 96.20% available for the pulsating amplitude of pressure deviating within a range of ~6% from the mean pressure. However, with a variation of speed deviating within a range of ±2% from the mean speed, the attainable test accuracy of flow ripple is above 93.07%. The model constructed in this research proposes a method to determine the flow ripple characteristics of pump and its attainable test accuracy under the large-scale and time-variant working conditions. Meanwhile, a discussion about the variation of flow ripple and its obtainable test accuracy with the conditions of the pump working in wide operating ranges is given as well.展开更多
AIM: To investigate the effects of proton pump inhibitor (PPI) treatment on stool antigen test using the TestMate pylori enzyme immunoassay. METHODS: This study assessed 28 patients [16 men and 12 women; mean age (63....AIM: To investigate the effects of proton pump inhibitor (PPI) treatment on stool antigen test using the TestMate pylori enzyme immunoassay. METHODS: This study assessed 28 patients [16 men and 12 women; mean age (63.1 ± 5.9) years; range, 25-84 years] who underwent stool antigen test and urea breath test (UBT) before and after PPI administration. RESULTS: Using the UBT as the standard, the sensitivity, specif icity and agreement of the stool antigen test in all 28 patients were 95.2%, 71.4%, and 89.3%, respectively, before PPI administration, and 88.9%, 90.9%, and 89.3%, respectively, after PPI treatment. Mean UBT values were 23.98% ± 5.33% before and 16.19% ± 4.75% after PPI treatment and, in 15 patients treated for ≥ 4 wk, were signif icantly lower after than before 4 wk of PPI treatment (12.58% ± 4.49% vs 24.53% ± 8.53%, P = 0.048). The mean optical density (A450/630) ratios on the stool antigen test were 1.16 ± 0.20 before and 1.17 ± 0.24 after PPI treatment (P = 0.989), and were 1.02 ± 0.26 and 0.69 ± 0.28, respectively, in the group treated for > 4 wk (P = 0.099).展开更多
The determination of aquifer parameters is the basis for groundwater resource evaluation,development and protection as well as scientific management. Pumping test is a main method to determine the aquifer parameters.H...The determination of aquifer parameters is the basis for groundwater resource evaluation,development and protection as well as scientific management. Pumping test is a main method to determine the aquifer parameters.However,the analytic methods can’t be used to describe the heterogeneous and spatial variant of the parameters in detail.The aquifer parameters derived from analytic methods may lead much uncertainty of groundwater resource evaluation.展开更多
The traditional testing method of a hydraulic pump requires a large amount of test data from a variety of pump working conditions. The test is usually time-consuming and energy-consu- ming. And the accurate characteri...The traditional testing method of a hydraulic pump requires a large amount of test data from a variety of pump working conditions. The test is usually time-consuming and energy-consu- ming. And the accurate characteristic curves of the pump were hardly obtained due to a limited a- mount and discreteness of the test data. In order to simplify the test procedure and improve the test accuracy, a novel method for measuring hydraulic pump operating characteristic based on multi-ele- ment nonlinear regression （NLMR） modeling is proposed in this paper. The main idea of this model- ing method is establishing a mathematical model to predict the performance parameters of the hy- draulic pump, only a small amount of test data is needed. Consequently, the pump operating charac- teristics in any working conditions are obtained. And the test results of the pump are easily charac- terized in the graphs, charts, tables and so on. The evaluations of the model are carried out and dis- cussed in this paper. The result shows that the test error of the novel method can be controlled to be about 0. 1%. Compared with the traditional test method, the proposed method reduces greatly the test time and the random error of the test data, and improves the efficiency and accuracy of the pump test.展开更多
Aquifers derived from the crystalline basement rocks for parts of Sanga Local Government area of Kaduna State, Nigeria consist of clay, silt, sand, gravel and laterite materials which may be in various proportions. Us...Aquifers derived from the crystalline basement rocks for parts of Sanga Local Government area of Kaduna State, Nigeria consist of clay, silt, sand, gravel and laterite materials which may be in various proportions. Using Cooper-Jacobs non-equilibrium graphical method, the hydraulic properties were estimated from pumping test data of 18 boreholes. Conductivity varies from 1.02 × 10<sup>﹣2</sup> m/s to 4.07 × 10<sup>﹣2</sup> m/s and transmissivity varies from 1.14 × 10<sup>﹣1</sup> m<sup>2</sup>/s to 4.40 × 10<sup>﹣1</sup> m<sup>2</sup>/s. The values of specific capacity range between 1.03 × 10<sup>﹣1</sup> m<sup>2</sup>/s/m and 9.00 × 10<sup>﹣2</sup> m<sup>2</sup>/s/m, and these values indicate that the aquifers in the area have low to moderate ground water potentials. The low yield range of between 0.45 l/s and 1.00 l/s recorded in the area shows the heterogeneous and anisotropy nature of the basement aquifer system in terms of groundwater discharge. On the average, the boreholes assessed have potentials to sustain local to regional supply provided the best drilling method and materials are used and well completion properly done.展开更多
Reliability of medical devices such as infusion pumps is extremely important because these devices are being used in patients who are in critical condition. Occlusion pressure, as an important parameter of infusion pu...Reliability of medical devices such as infusion pumps is extremely important because these devices are being used in patients who are in critical condition. Occlusion pressure, as an important parameter of infusion pumps, should be detected when an occlusion occurred. How-ever, infusion pumps’ occlusion pressure could not be tested and the performance of these pumps is not known to us. In order to test the occlusion pressure of infusion pump, a testing system has been put forward according to standards of IEC 60601-2-24:1998/ GB 9706.27- 2005. The system is comprised of sensor, acquisition card, three-way tap and so on;this system is controlled by a PC. At the same time, sampling rate could be changed if necessary and test time could be recorded. And then the characteristics of this system were studied, such as linear, effects of pump rates and different pumps. The system remained linear in a given environment. The higher is the pump rate, the faster is the time to reach occlusion condi-tion. The testing system has been proved to be effective in testing the occlusion pressure of infusion pumps and the accuracy error of pressure is content the demand of ±1% of range.展开更多
The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with an...The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with any model of Bosch injection pump test benches for PT Pumps and injector calibration. During PT Pump calibration, the type PT-821 test stand should be used in conjunction with a Bosch injection pump lest bench. The PT Pump to be tested is installed on the Bosch injection pump test bench through a mounting bracket and is driven by the bench shaft. When calibrating PT injectors, both the PT-881 injector test stand and the PT-821 PT Pump test stand should be used in conjunction with a Bosch injection pump test bench, with the PT-881 injector test stand installed on Bosch test bench. The injector to be tested is driven by the Bosch injection pump test bench through a coupling. This paper describes the structure and function of the PT-821 PT Pump test stand and PT-881 injector test stand. Some technical problems arc described in detail.展开更多
The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at ...The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at present.To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions,inner flows in a double blade pump impeller,whose specific speed is 111,are measured under the five off-design conditions and design condition by using 3D PIV test technology.In order to ensure the accuracy of the 3D PIV test,the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied.The 3D PIV relative velocity synthesis procedure is compiled by using Visual C＋＋ 2005.Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained.Test results show that vortex exists in each condition,but the location,size and velocity of vortex core are different.Average absolute velocity value of impeller outlet increases at first,then decreases,and then increases again with increase of flow rate.Again average relative velocity values under 0.4,0.8,and 1.2 design condition are higher than that under 1.0 design condition,while under 0.6 and 1.4 design condition it is lower.Under low flow rate conditions,radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate,while that of relative velocities at the suction side near the pump shaft decreases.Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions.The research results can be applied to instruct the hydraulic optimization design of double blade pumps.展开更多
基金the Ministerial Level Advanced Research Foundation (404050301 .4)
文摘A unit pump test bench is developed on an in-line pump test platform. The bench is composed of pump adapting assembly, fuel supply subsystem, lubricating subsystem and a control unit. A crank angle domain injection control method is given out and the control accuracy can be 0.1° crank degree. The bench can test both mechanical unit pump and electronic unit pump. A test model-PLD12 electronic unit pump is tested. Full pump delivery map and some influence factors test is done. Experimental results show that the injection quantity is linear with the delivery angle. The quantity change rate is 15% when fuel temperature increases 30 ℃. The delivery quantity per cycle increases 30 mg at 28 V drive voltage. The average delivery difference for two same type pumps is 5 %. Test results show that the bench can be used for unit pump verification.
文摘Pumping test of a water table aquifer is carried out to estimate the aquifer parameters, the obtained data were analysed through the solution of both Neuman(1975) and Jacob(1946) methods through AQTESOLV and Spreadsheet programs, the results of each methods are compared to evaluate the applicability and accuracy of the solution theoretically and practically. In the paper an example is presented, which is conducted for a constant rate pumping test from Ohio, in Fairborn(near Dayton), and it supplied by S.E. Norris(U.S. Geological Survey, Columbus, Ohio). The main objective of this study is to introduce both program and the way of the applications, and compare the results and the hand on of both programs in the field.
文摘The origin and movement of groundwater are the fundamental questions that address both the temporal and spatial aspects of ground water run and water supply related issues in hydrological systems.As groundwater flows through an aquifer,its composition and temperature may variation dependent on the aquifer condition through which it flows.Thus,hydrologic investigations can also provide useful information about the subsurface geology of a region.But because such studies investigate processes that follow under the Earth's shallow,obtaining the information necessary to answer these questions is not continuously easy.Springs,which discharge groundwater table directly,afford to study subsurface hydrogeological processes.The present study of estimation of aquifer factors such as transmissivity(T)and storativity(S)are vital for the evaluation of groundwater resources.There are several methods to estimate the accurate aquifer parameters(i.e.hydrograph analysis,pumping test,etc.).In initial days,these parameters are projected either by means of in-situ test or execution test on aquifer well samples carried in the laboratory.The simultaneous information on the hydraulic behavior of the well(borehole)that provides on this method,the reservoir and the reservoir boundaries,are important for efficient aquifer and well data management and analysis.The most common in-situ test is pumping test performed on wells,which involves the measurement of the fall and increase of groundwater level with respect to time.The alteration in groundwater level(drawdown/recovery)is caused due to pumping of water from the well.Theis(1935)was first to propose method to evaluate aquifer parameters from the pumping test on a bore well in a confined aquifer.It is essential to know the transmissivity(T=Kb,where b is the aquifer thickness;pumping flow rate,Q=TW(dh/dl)flow through an aquifer)and storativity(confined aquifer:S=bS_s,unconfined:S=S_y),for the characterization of the aquifer parameters in an unknown area so as to predict the rate of drawdown of the groundwater table/potentiometric surface throughout the pumping test of an aquifer.The determination of aquifer's parameters is an important basis for groundwater resources evaluation,numerical simulation,development and protection as well as scientific management.For determining aquifer's parameters,pumping test is a main method.A case study shows that these techniques have been fast speed and high correctness.The results of parameter's determination are optimized so that it has important applied value for scientific research and geology engineering preparation.
基金Supported by National Basic Research Program of China(973 Program,Grant No.2014CB046403)National Key Technology R&D Program of the Twelfth Five-year Plan of China(Grant No.2013BAF07B01)
文摘The current research about the flow ripple of axial piston pump mainly focuses on the effect of the structure of parts on the flow ripple. Therein, the structure of parts are usually designed and optimized at rated working conditions. However, the pump usually has to work in large-scale and time-variant working conditions. Therefore, the flow ripple characteristics of pump and analysis for its test accuracy with respect to variant steady-state conditions and transient conditions in a wide range of operating parameters are focused in this paper. First, a simulation model has been constructed, which takes the kinematics of oil film within friction pairs into account for higher accuracy. Afterwards, a test bed which adopts Secondary Source Method is built to verify the model. The simulation and tests results show that the angular position of the piston, corresponding to the position where the peak flow ripple is produced, varies with the different pressure. The pulsating amplitude and pulsation rate of flow ripple increase with the rise of pressure and the variation rate of pressure. For the pump working at a constant speed, the flow pulsation rate decreases dramatically with the increasing speed when the speed is less than 27.78% of the maximum speed, subsequently presents a small decrease tendency with the speed further increasing. With the rise of the variation rate of speed, the pulsating amplitude and pulsation rate of flow ripple increase. As the swash plate angle augments, the pulsating amplitude of flow ripple increases, nevertheless the flow pulsation rate decreases. In contrast with the effect of the variation of pressure, the test accuracy of flow ripple is more sensitive to the variation of speed. It makes the test accuracy above 96.20% available for the pulsating amplitude of pressure deviating within a range of ~6% from the mean pressure. However, with a variation of speed deviating within a range of ±2% from the mean speed, the attainable test accuracy of flow ripple is above 93.07%. The model constructed in this research proposes a method to determine the flow ripple characteristics of pump and its attainable test accuracy under the large-scale and time-variant working conditions. Meanwhile, a discussion about the variation of flow ripple and its obtainable test accuracy with the conditions of the pump working in wide operating ranges is given as well.
文摘AIM: To investigate the effects of proton pump inhibitor (PPI) treatment on stool antigen test using the TestMate pylori enzyme immunoassay. METHODS: This study assessed 28 patients [16 men and 12 women; mean age (63.1 ± 5.9) years; range, 25-84 years] who underwent stool antigen test and urea breath test (UBT) before and after PPI administration. RESULTS: Using the UBT as the standard, the sensitivity, specif icity and agreement of the stool antigen test in all 28 patients were 95.2%, 71.4%, and 89.3%, respectively, before PPI administration, and 88.9%, 90.9%, and 89.3%, respectively, after PPI treatment. Mean UBT values were 23.98% ± 5.33% before and 16.19% ± 4.75% after PPI treatment and, in 15 patients treated for ≥ 4 wk, were signif icantly lower after than before 4 wk of PPI treatment (12.58% ± 4.49% vs 24.53% ± 8.53%, P = 0.048). The mean optical density (A450/630) ratios on the stool antigen test were 1.16 ± 0.20 before and 1.17 ± 0.24 after PPI treatment (P = 0.989), and were 1.02 ± 0.26 and 0.69 ± 0.28, respectively, in the group treated for > 4 wk (P = 0.099).
文摘The determination of aquifer parameters is the basis for groundwater resource evaluation,development and protection as well as scientific management. Pumping test is a main method to determine the aquifer parameters.However,the analytic methods can’t be used to describe the heterogeneous and spatial variant of the parameters in detail.The aquifer parameters derived from analytic methods may lead much uncertainty of groundwater resource evaluation.
基金Supported by the National Science & Technology Pillar Program During the 12th Five-Year Plan Period(2014BAF08B06)the Research Foundation of Beijing Institute of Technology20110601061)
文摘The traditional testing method of a hydraulic pump requires a large amount of test data from a variety of pump working conditions. The test is usually time-consuming and energy-consu- ming. And the accurate characteristic curves of the pump were hardly obtained due to a limited a- mount and discreteness of the test data. In order to simplify the test procedure and improve the test accuracy, a novel method for measuring hydraulic pump operating characteristic based on multi-ele- ment nonlinear regression （NLMR） modeling is proposed in this paper. The main idea of this model- ing method is establishing a mathematical model to predict the performance parameters of the hy- draulic pump, only a small amount of test data is needed. Consequently, the pump operating charac- teristics in any working conditions are obtained. And the test results of the pump are easily charac- terized in the graphs, charts, tables and so on. The evaluations of the model are carried out and dis- cussed in this paper. The result shows that the test error of the novel method can be controlled to be about 0. 1%. Compared with the traditional test method, the proposed method reduces greatly the test time and the random error of the test data, and improves the efficiency and accuracy of the pump test.
文摘Aquifers derived from the crystalline basement rocks for parts of Sanga Local Government area of Kaduna State, Nigeria consist of clay, silt, sand, gravel and laterite materials which may be in various proportions. Using Cooper-Jacobs non-equilibrium graphical method, the hydraulic properties were estimated from pumping test data of 18 boreholes. Conductivity varies from 1.02 × 10<sup>﹣2</sup> m/s to 4.07 × 10<sup>﹣2</sup> m/s and transmissivity varies from 1.14 × 10<sup>﹣1</sup> m<sup>2</sup>/s to 4.40 × 10<sup>﹣1</sup> m<sup>2</sup>/s. The values of specific capacity range between 1.03 × 10<sup>﹣1</sup> m<sup>2</sup>/s/m and 9.00 × 10<sup>﹣2</sup> m<sup>2</sup>/s/m, and these values indicate that the aquifers in the area have low to moderate ground water potentials. The low yield range of between 0.45 l/s and 1.00 l/s recorded in the area shows the heterogeneous and anisotropy nature of the basement aquifer system in terms of groundwater discharge. On the average, the boreholes assessed have potentials to sustain local to regional supply provided the best drilling method and materials are used and well completion properly done.
文摘Reliability of medical devices such as infusion pumps is extremely important because these devices are being used in patients who are in critical condition. Occlusion pressure, as an important parameter of infusion pumps, should be detected when an occlusion occurred. How-ever, infusion pumps’ occlusion pressure could not be tested and the performance of these pumps is not known to us. In order to test the occlusion pressure of infusion pump, a testing system has been put forward according to standards of IEC 60601-2-24:1998/ GB 9706.27- 2005. The system is comprised of sensor, acquisition card, three-way tap and so on;this system is controlled by a PC. At the same time, sampling rate could be changed if necessary and test time could be recorded. And then the characteristics of this system were studied, such as linear, effects of pump rates and different pumps. The system remained linear in a given environment. The higher is the pump rate, the faster is the time to reach occlusion condi-tion. The testing system has been proved to be effective in testing the occlusion pressure of infusion pumps and the accuracy error of pressure is content the demand of ±1% of range.
文摘The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with any model of Bosch injection pump test benches for PT Pumps and injector calibration. During PT Pump calibration, the type PT-821 test stand should be used in conjunction with a Bosch injection pump lest bench. The PT Pump to be tested is installed on the Bosch injection pump test bench through a mounting bracket and is driven by the bench shaft. When calibrating PT injectors, both the PT-881 injector test stand and the PT-821 PT Pump test stand should be used in conjunction with a Bosch injection pump test bench, with the PT-881 injector test stand installed on Bosch test bench. The injector to be tested is driven by the Bosch injection pump test bench through a coupling. This paper describes the structure and function of the PT-821 PT Pump test stand and PT-881 injector test stand. Some technical problems arc described in detail.
基金supported by National Outstanding Young Scientists Founds of China (Grant No. 50825902)National Key Technology R&D Program of China (Grant No. 2008BAF34B15)+2 种基金National Natural Science Foundation of China (Grant No. 51079062)Jiangsu Provincial 333 High-level Personal Training Project of ChinaJiangsu Provincial Six Talent Peak of China
文摘The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at present.To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions,inner flows in a double blade pump impeller,whose specific speed is 111,are measured under the five off-design conditions and design condition by using 3D PIV test technology.In order to ensure the accuracy of the 3D PIV test,the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied.The 3D PIV relative velocity synthesis procedure is compiled by using Visual C＋＋ 2005.Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained.Test results show that vortex exists in each condition,but the location,size and velocity of vortex core are different.Average absolute velocity value of impeller outlet increases at first,then decreases,and then increases again with increase of flow rate.Again average relative velocity values under 0.4,0.8,and 1.2 design condition are higher than that under 1.0 design condition,while under 0.6 and 1.4 design condition it is lower.Under low flow rate conditions,radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate,while that of relative velocities at the suction side near the pump shaft decreases.Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions.The research results can be applied to instruct the hydraulic optimization design of double blade pumps.
