The Experts below are selected from a list of 17853 Experts worldwide ranked by ideXlab platform

Wenjie Wang - One of the best experts on this subject based on the ideXlab platform.

  • numerical analysis of pressure fluctuation intensity for a low speed sewage centrifugal pump
    Advances in Mechanical Engineering, 2014
    Co-Authors: Shouqi Yuan, Wenjie Wang
    Abstract:

    Sewage centrifugal pumps can operate at different flow rates with variable rotating speeds to meet different performance requirements and achieve certain energy consumption criteria in pipeline systems. In this paper, the unsteady pressure field has been investigated numerically by CFD calculation to evaluate the transient pressure variation in a single-blade pump running with low rotating speeds. Based on the CFD results, the pressure fluctuation intensity was analyzed quantitatively by defining the standard deviation of the pressure fluctuation of a revolution period. The analysis of the results shows that the flow rate can influence the fluctuation intensity distribution obviously, and the same intensity distribution law can be found in the volute domain for the same flow rates with different rotating speeds. Obvious asymmetrical distributions can be observed in both front and back Side Chamber channels, and the pressure fluctuation intensity in back Side Chamber is weaker than in front Side Chamber. T...

  • The influence of the flow rate on periodic flow unsteadiness behaviors in a sewage centrifugal pump
    Journal of Hydrodynamics, 2013
    Co-Authors: Ji Pei, Shouqi Yuan, Jianping Yuan, Wenjie Wang
    Abstract:

    To design a single-blade pump with a good performance in a wide operational range and to increase the pump reliability in the multi-conditional hydraulic design process, an understanding of the unsteady flow behaviors as related with the flow rate is very important. However, the traditional design often conSiders only a single design condition, and the unsteady flow behaviors have not been well studied for single-blade pumps under different conditions. A comparison analysis of the flow unsteadiness behaviors at different flow rates within the whole flow passage of the pump is carried out in this paper by solving the three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with the Shear Stress Transport (SST) turbulence model. A definition of the unsteadiness in the pump is made and applied to analyze the unsteady intensity distributions, and the flow rate effect on the complex unsteady flow in the pump is studied quantitatively while the flow mechanism is also analyzed. The CFD results are validated by experimental data collected at the laboratory. It is shown that a significant flow rate effect on the time-averaged unsteadiness and the turbulence intensity distribution can be observed in both rotor and stator domains including the Side Chamber. The findings would be useful to reduce the flow unsteadiness and to increase the pump reliability under multi-conditions.

  • Numerical Investigation on Periodic Flow Unsteadiness in a Centrifugal Pump With Volute
    Volume 1B Symposia: Fluid Machinery; Fluid Power; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in , 2013
    Co-Authors: Ji Pei, Shouqi Yuan, Jianping Yuan, Li Xiaojun, Wenjie Wang
    Abstract:

    In this paper, the CFD simulation and flow unsteadiness analysis for a centrifugal pump with volute were carried out in whole flow passage including impeller, volute and Side Chamber. The periodic flow unsteadiness based on URANS equations has been quantitatively investigated in detail by defining unsteady velocity intensity, and turbulence intensity under design condition was also studied. Meanwhile, three-dimensional effect has been conSidered for the twisted blade channels. The time-averaged unsteady velocity intensity and time-averaged turbulence intensity were calculated by averaging the results of each grid node for entire impeller revolution period to evaluate the strength distributions of flow unsteadiness directly and comprehensively. The accumulative results of an impeller revolution can directly show the positions and strength of the flow unsteadiness and turbulence intensity in both rotor and stator domains which can be an important aspect to be conSidered in the centrifugal pump optimum design procedure for obtaining more stable inner flow of the pump and cutting down certain components of flow-induced vibration and noise.© 2013 ASME

Babak Nasiri - One of the best experts on this subject based on the ideXlab platform.

  • Myxoma of the superior vena cava origin presented as a right atrial mass.
    The journal of Tehran Heart Center, 2013
    Co-Authors: Feridoun Sabzi, Babak Nasiri
    Abstract:

    Myxomas are the most common benign cardiac tumors. Myxomas are more common in the left heart Chamber than the right Side Chamber. An extracardiac origin presenting as a right atrial mass is very rare. We present a case of myxoma originating in the superior vena cava (SVC) in a 24-year-old man, who underwent surgical resection. Preoperative two-dimensional echocardiography demonstrated a mass in the right atrium. Intraoperatively, the tumor was found to have originated from the SVC orifice. The tumor was excised from the SVC by opening the one-third proximal portion of the SVC. Pathological examination revealed a myxoma, and one-year follow-up showed no evidence of the recurrence of any tumors in the SVC.

Shouqi Yuan - One of the best experts on this subject based on the ideXlab platform.

  • numerical analysis of pressure fluctuation intensity for a low speed sewage centrifugal pump
    Advances in Mechanical Engineering, 2014
    Co-Authors: Shouqi Yuan, Wenjie Wang
    Abstract:

    Sewage centrifugal pumps can operate at different flow rates with variable rotating speeds to meet different performance requirements and achieve certain energy consumption criteria in pipeline systems. In this paper, the unsteady pressure field has been investigated numerically by CFD calculation to evaluate the transient pressure variation in a single-blade pump running with low rotating speeds. Based on the CFD results, the pressure fluctuation intensity was analyzed quantitatively by defining the standard deviation of the pressure fluctuation of a revolution period. The analysis of the results shows that the flow rate can influence the fluctuation intensity distribution obviously, and the same intensity distribution law can be found in the volute domain for the same flow rates with different rotating speeds. Obvious asymmetrical distributions can be observed in both front and back Side Chamber channels, and the pressure fluctuation intensity in back Side Chamber is weaker than in front Side Chamber. T...

  • Numerical prediction of 3-D periodic flow unsteadiness in a centrifugal pump under part-load condition
    Journal of Hydrodynamics, 2014
    Co-Authors: Ji Pei, Shouqi Yuan, Jianping Yuan
    Abstract:

    Abstract Numerical simulation and 3-D periodic flow unsteadiness analysis for a centrifugal pump with volute are carried out in whole flow passage, including the impeller with twisted blades, the volute and the Side Chamber channels under a part-load condition. The pressure fluctuation intensity coefficient (PFIC) based on the standard deviation method, the time-averaged velocity unsteadi- ness intensity coefficient (VUIC) and the time-averaged turbulence intensity coefficient (TIC) are defined by averaging the results at each grid node for an entire impeller revolution period. Therefore, the strength distributions of the periodic flow unsteadiness based on the unsteady Reynolds-averaged Navier-Stokes (URANS) equations can be analyzed directly and in detail. It is shown that under the 0.6 Q des. condition, the pressure fluctuation intensity is larger near the blade pressure Side than near the suction Side, and a high fluctuation intensity can be observed at the beginning section of the spiral of the volute. The flow velocity unsteadiness intensity is larger near the blade suction Side than near the pressure Side. A strong turbulence intensity can be found near the blade suction Side, the impeller shroud Side as well as in the Side Chamber. The leakage flow has a significant effect on the inflow of the impeller, and can increase both the flow velocity unsteadiness intensity and the turbulence intensity near the wall. The accumulative flow unstea- diness results of an impeller revolution can be an important aspect to be conSidered in the centrifugal pump optimum design for ob- taining a more stable inner flow of the pump and reducing the flow-induced vibration and noise in certain components.

  • The influence of the flow rate on periodic flow unsteadiness behaviors in a sewage centrifugal pump
    Journal of Hydrodynamics, 2013
    Co-Authors: Ji Pei, Shouqi Yuan, Jianping Yuan, Wenjie Wang
    Abstract:

    To design a single-blade pump with a good performance in a wide operational range and to increase the pump reliability in the multi-conditional hydraulic design process, an understanding of the unsteady flow behaviors as related with the flow rate is very important. However, the traditional design often conSiders only a single design condition, and the unsteady flow behaviors have not been well studied for single-blade pumps under different conditions. A comparison analysis of the flow unsteadiness behaviors at different flow rates within the whole flow passage of the pump is carried out in this paper by solving the three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with the Shear Stress Transport (SST) turbulence model. A definition of the unsteadiness in the pump is made and applied to analyze the unsteady intensity distributions, and the flow rate effect on the complex unsteady flow in the pump is studied quantitatively while the flow mechanism is also analyzed. The CFD results are validated by experimental data collected at the laboratory. It is shown that a significant flow rate effect on the time-averaged unsteadiness and the turbulence intensity distribution can be observed in both rotor and stator domains including the Side Chamber. The findings would be useful to reduce the flow unsteadiness and to increase the pump reliability under multi-conditions.

  • Numerical Investigation on Periodic Flow Unsteadiness in a Centrifugal Pump With Volute
    Volume 1B Symposia: Fluid Machinery; Fluid Power; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in , 2013
    Co-Authors: Ji Pei, Shouqi Yuan, Jianping Yuan, Li Xiaojun, Wenjie Wang
    Abstract:

    In this paper, the CFD simulation and flow unsteadiness analysis for a centrifugal pump with volute were carried out in whole flow passage including impeller, volute and Side Chamber. The periodic flow unsteadiness based on URANS equations has been quantitatively investigated in detail by defining unsteady velocity intensity, and turbulence intensity under design condition was also studied. Meanwhile, three-dimensional effect has been conSidered for the twisted blade channels. The time-averaged unsteady velocity intensity and time-averaged turbulence intensity were calculated by averaging the results of each grid node for entire impeller revolution period to evaluate the strength distributions of flow unsteadiness directly and comprehensively. The accumulative results of an impeller revolution can directly show the positions and strength of the flow unsteadiness and turbulence intensity in both rotor and stator domains which can be an important aspect to be conSidered in the centrifugal pump optimum design procedure for obtaining more stable inner flow of the pump and cutting down certain components of flow-induced vibration and noise.© 2013 ASME

  • Numerical Prediction of Unsteady Pressure Field Within the Whole Flow Passage of a Radial Single-Blade Pump
    Journal of Fluids Engineering, 2012
    Co-Authors: Ji Pei, Shouqi Yuan, Friedrich-karl Benra, Hans Josef Dohmen
    Abstract:

    In this paper, the periodically unsteady pressure field caused by rotor-stator interaction has been investigated numerically by computational fluid dynamics (CFD) calculation to evaluate the transient pressure variation in a single-blade pump for multiconditions. Side Chamber flow effect is also conSidered for the simulation to accurately predict the flow in a whole-flow passage. The strength of the pressure fluctuation is analyzed quantitatively by defining the standard deviation of the pressure fluctuation of a revolution period. The analysis of the results shows that higher pressure fluctuation magnitudes can be observed near the blade pressure Side and high gradients of fluctuation magnitudes can be obtained at the trailing edge near the pressure Side of the blade. An asymmetrical distribution of fluctuation magnitudes in the volute domain can be clearly obtained. On the cylindrical surface around the impeller outlet, although the absolute pressure value is higher for the Q = 11 l/s condition, the magnitude distribution of fluctuations is lower, and a relatively symmetrical fluctuation distribution is obtained for the Q = 22 l/s condition when clearly asymmetrical distributions of fluctuation magnitude can be observed for the design point and for large flow rates. Obvious periodicity can be observed for the pressure fluctuation magnitude distribution on the circumference with different radii in the volute domain, and some subpeaks and subvalleys can be found. The effects of unsteady flow in the Side Chambers on the entire passage flow cannot be neglected for accurately predicting the inner flow of the pump. The results of unsteady pressure fluctuation magnitude can be used to guide the optimum design of the single-blade pump to decrease the hydrodynamic unbalance and to obtain more stable performance of the pump.

Feridoun Sabzi - One of the best experts on this subject based on the ideXlab platform.

  • Myxoma of the superior vena cava origin presented as a right atrial mass.
    The journal of Tehran Heart Center, 2013
    Co-Authors: Feridoun Sabzi, Babak Nasiri
    Abstract:

    Myxomas are the most common benign cardiac tumors. Myxomas are more common in the left heart Chamber than the right Side Chamber. An extracardiac origin presenting as a right atrial mass is very rare. We present a case of myxoma originating in the superior vena cava (SVC) in a 24-year-old man, who underwent surgical resection. Preoperative two-dimensional echocardiography demonstrated a mass in the right atrium. Intraoperatively, the tumor was found to have originated from the SVC orifice. The tumor was excised from the SVC by opening the one-third proximal portion of the SVC. Pathological examination revealed a myxoma, and one-year follow-up showed no evidence of the recurrence of any tumors in the SVC.

Ji Pei - One of the best experts on this subject based on the ideXlab platform.

  • Numerical prediction of 3-D periodic flow unsteadiness in a centrifugal pump under part-load condition
    Journal of Hydrodynamics, 2014
    Co-Authors: Ji Pei, Shouqi Yuan, Jianping Yuan
    Abstract:

    Abstract Numerical simulation and 3-D periodic flow unsteadiness analysis for a centrifugal pump with volute are carried out in whole flow passage, including the impeller with twisted blades, the volute and the Side Chamber channels under a part-load condition. The pressure fluctuation intensity coefficient (PFIC) based on the standard deviation method, the time-averaged velocity unsteadi- ness intensity coefficient (VUIC) and the time-averaged turbulence intensity coefficient (TIC) are defined by averaging the results at each grid node for an entire impeller revolution period. Therefore, the strength distributions of the periodic flow unsteadiness based on the unsteady Reynolds-averaged Navier-Stokes (URANS) equations can be analyzed directly and in detail. It is shown that under the 0.6 Q des. condition, the pressure fluctuation intensity is larger near the blade pressure Side than near the suction Side, and a high fluctuation intensity can be observed at the beginning section of the spiral of the volute. The flow velocity unsteadiness intensity is larger near the blade suction Side than near the pressure Side. A strong turbulence intensity can be found near the blade suction Side, the impeller shroud Side as well as in the Side Chamber. The leakage flow has a significant effect on the inflow of the impeller, and can increase both the flow velocity unsteadiness intensity and the turbulence intensity near the wall. The accumulative flow unstea- diness results of an impeller revolution can be an important aspect to be conSidered in the centrifugal pump optimum design for ob- taining a more stable inner flow of the pump and reducing the flow-induced vibration and noise in certain components.

  • The influence of the flow rate on periodic flow unsteadiness behaviors in a sewage centrifugal pump
    Journal of Hydrodynamics, 2013
    Co-Authors: Ji Pei, Shouqi Yuan, Jianping Yuan, Wenjie Wang
    Abstract:

    To design a single-blade pump with a good performance in a wide operational range and to increase the pump reliability in the multi-conditional hydraulic design process, an understanding of the unsteady flow behaviors as related with the flow rate is very important. However, the traditional design often conSiders only a single design condition, and the unsteady flow behaviors have not been well studied for single-blade pumps under different conditions. A comparison analysis of the flow unsteadiness behaviors at different flow rates within the whole flow passage of the pump is carried out in this paper by solving the three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with the Shear Stress Transport (SST) turbulence model. A definition of the unsteadiness in the pump is made and applied to analyze the unsteady intensity distributions, and the flow rate effect on the complex unsteady flow in the pump is studied quantitatively while the flow mechanism is also analyzed. The CFD results are validated by experimental data collected at the laboratory. It is shown that a significant flow rate effect on the time-averaged unsteadiness and the turbulence intensity distribution can be observed in both rotor and stator domains including the Side Chamber. The findings would be useful to reduce the flow unsteadiness and to increase the pump reliability under multi-conditions.

  • Numerical Investigation on Periodic Flow Unsteadiness in a Centrifugal Pump With Volute
    Volume 1B Symposia: Fluid Machinery; Fluid Power; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in , 2013
    Co-Authors: Ji Pei, Shouqi Yuan, Jianping Yuan, Li Xiaojun, Wenjie Wang
    Abstract:

    In this paper, the CFD simulation and flow unsteadiness analysis for a centrifugal pump with volute were carried out in whole flow passage including impeller, volute and Side Chamber. The periodic flow unsteadiness based on URANS equations has been quantitatively investigated in detail by defining unsteady velocity intensity, and turbulence intensity under design condition was also studied. Meanwhile, three-dimensional effect has been conSidered for the twisted blade channels. The time-averaged unsteady velocity intensity and time-averaged turbulence intensity were calculated by averaging the results of each grid node for entire impeller revolution period to evaluate the strength distributions of flow unsteadiness directly and comprehensively. The accumulative results of an impeller revolution can directly show the positions and strength of the flow unsteadiness and turbulence intensity in both rotor and stator domains which can be an important aspect to be conSidered in the centrifugal pump optimum design procedure for obtaining more stable inner flow of the pump and cutting down certain components of flow-induced vibration and noise.© 2013 ASME

  • Numerical Prediction of Unsteady Pressure Field Within the Whole Flow Passage of a Radial Single-Blade Pump
    Journal of Fluids Engineering, 2012
    Co-Authors: Ji Pei, Shouqi Yuan, Friedrich-karl Benra, Hans Josef Dohmen
    Abstract:

    In this paper, the periodically unsteady pressure field caused by rotor-stator interaction has been investigated numerically by computational fluid dynamics (CFD) calculation to evaluate the transient pressure variation in a single-blade pump for multiconditions. Side Chamber flow effect is also conSidered for the simulation to accurately predict the flow in a whole-flow passage. The strength of the pressure fluctuation is analyzed quantitatively by defining the standard deviation of the pressure fluctuation of a revolution period. The analysis of the results shows that higher pressure fluctuation magnitudes can be observed near the blade pressure Side and high gradients of fluctuation magnitudes can be obtained at the trailing edge near the pressure Side of the blade. An asymmetrical distribution of fluctuation magnitudes in the volute domain can be clearly obtained. On the cylindrical surface around the impeller outlet, although the absolute pressure value is higher for the Q = 11 l/s condition, the magnitude distribution of fluctuations is lower, and a relatively symmetrical fluctuation distribution is obtained for the Q = 22 l/s condition when clearly asymmetrical distributions of fluctuation magnitude can be observed for the design point and for large flow rates. Obvious periodicity can be observed for the pressure fluctuation magnitude distribution on the circumference with different radii in the volute domain, and some subpeaks and subvalleys can be found. The effects of unsteady flow in the Side Chambers on the entire passage flow cannot be neglected for accurately predicting the inner flow of the pump. The results of unsteady pressure fluctuation magnitude can be used to guide the optimum design of the single-blade pump to decrease the hydrodynamic unbalance and to obtain more stable performance of the pump.