Centrifugal compressors with parallel-wall and contracting wall vaneless diffuser are designed by using centrifugal compressor computer-aided integrated design system. The internal flow fields of the compressor are ca...Centrifugal compressors with parallel-wall and contracting wall vaneless diffuser are designed by using centrifugal compressor computer-aided integrated design system. The internal flow fields of the compressor are calculated by solving three-dimensional Navier-Stokes equation. Four aspects are investigated and calculation results show that the total efficiencies and total pressure ratios of the compressor with contracting wall vandess diffuser is higher than that of the compressor with parallel-wall. The jet and wake don＇t mix rapidly inside vandess diffuser. The outlet blade lean angle doesn＇t affect the compressor performance. The greater the mass flow rate through impeller, the more uneven the velocity distribution at impeller outlet is.展开更多
The paper refers to the analysis of interactions between the impeller and the vaned diffuser based on the air model of a radial flow pump.The study deals with a numerical simulation of the flow for a full 360°ent...The paper refers to the analysis of interactions between the impeller and the vaned diffuser based on the air model of a radial flow pump.The study deals with a numerical simulation of the flow for a full 360°entire impeller and diffuser.The task is carried out closely under the design operating conditions and for one particular position of the impeller blade with respect to the diffuser frame.Among all the results,the focus is mainly on the flow pattern at the exit part inside the impeller facing the diffuser vanes.The results are compared to the available PIV measurements.展开更多
Numerical simulation on the unsteady flow in a centrifugal compressor isperformed, and compared with the experimental data. The influence of the impeller-diffuserinteraction on the flow-fields is discussed, and the re...Numerical simulation on the unsteady flow in a centrifugal compressor isperformed, and compared with the experimental data. The influence of the impeller-diffuserinteraction on the flow-fields is discussed, and the reasons for the losses are also explored.Results show that qualitative and quite fair quantitative agreements are achieved between thepredicted and measured flowfields. The influence of the impeller wake on the convexity surface ofdiffuser is great. The potential repercussion of the diffuser on the suction surface of the impelleris much larger than on the pressure surface. Effect of the unsteady interaction is strongest in theradial gap. The unsteady flow itself may compensate for the loss generated in stage, and the stageefficiency is inversely proportional to the entropy production.展开更多
The strong interaction in a radial pump due to the relative movement between the impeller and the diffuser may excite not only strong pressure fluctuations but also velocity fluctuations. In this paper, the laser Dopp...The strong interaction in a radial pump due to the relative movement between the impeller and the diffuser may excite not only strong pressure fluctuations but also velocity fluctuations. In this paper, the laser Doppler velocimetry （LDV） technique is successfully applied to measure the periodic flow field in a radial diffuser pump with low-specific speed, in order to investigate the velocity fluctuations caused by the impeller-diffuser interactions both in the impeller and diffuser regions. The velocity fluctuations in the impeller region are quantitatively examined at different radial positions, and the flow structure at the radial gap between two flow components is analyzed at different relative positions. In addition, the downstream effect on the diffuser flow is quantitatively and qualitatively assessed and compared with the turbulence effect.展开更多
文摘Centrifugal compressors with parallel-wall and contracting wall vaneless diffuser are designed by using centrifugal compressor computer-aided integrated design system. The internal flow fields of the compressor are calculated by solving three-dimensional Navier-Stokes equation. Four aspects are investigated and calculation results show that the total efficiencies and total pressure ratios of the compressor with contracting wall vandess diffuser is higher than that of the compressor with parallel-wall. The jet and wake don＇t mix rapidly inside vandess diffuser. The outlet blade lean angle doesn＇t affect the compressor performance. The greater the mass flow rate through impeller, the more uneven the velocity distribution at impeller outlet is.
文摘The paper refers to the analysis of interactions between the impeller and the vaned diffuser based on the air model of a radial flow pump.The study deals with a numerical simulation of the flow for a full 360°entire impeller and diffuser.The task is carried out closely under the design operating conditions and for one particular position of the impeller blade with respect to the diffuser frame.Among all the results,the focus is mainly on the flow pattern at the exit part inside the impeller facing the diffuser vanes.The results are compared to the available PIV measurements.
文摘Numerical simulation on the unsteady flow in a centrifugal compressor isperformed, and compared with the experimental data. The influence of the impeller-diffuserinteraction on the flow-fields is discussed, and the reasons for the losses are also explored.Results show that qualitative and quite fair quantitative agreements are achieved between thepredicted and measured flowfields. The influence of the impeller wake on the convexity surface ofdiffuser is great. The potential repercussion of the diffuser on the suction surface of the impelleris much larger than on the pressure surface. Effect of the unsteady interaction is strongest in theradial gap. The unsteady flow itself may compensate for the loss generated in stage, and the stageefficiency is inversely proportional to the entropy production.
基金supported by the National Natural Science Foundation of China(Grant Nos.51339005,51379174 and 51279160)the Doctoral Fund of Ministry of Education of China(Grant No.20126118130002)
文摘The strong interaction in a radial pump due to the relative movement between the impeller and the diffuser may excite not only strong pressure fluctuations but also velocity fluctuations. In this paper, the laser Doppler velocimetry （LDV） technique is successfully applied to measure the periodic flow field in a radial diffuser pump with low-specific speed, in order to investigate the velocity fluctuations caused by the impeller-diffuser interactions both in the impeller and diffuser regions. The velocity fluctuations in the impeller region are quantitatively examined at different radial positions, and the flow structure at the radial gap between two flow components is analyzed at different relative positions. In addition, the downstream effect on the diffuser flow is quantitatively and qualitatively assessed and compared with the turbulence effect.
