To investigate the unsteady flow characteristics in centrifugal pump, the flow field in a low-specific-speed centri- fugal pump with complex impeller is numerically simulated under different conditions. The RNG r-e tu...To investigate the unsteady flow characteristics in centrifugal pump, the flow field in a low-specific-speed centri- fugal pump with complex impeller is numerically simulated under different conditions. The RNG r-e turbulence model and sliding mesh are adopted during the process of computation. The results show that the interaction be- tween impeller and volute results in the unstable flow of the fluid, which causes the uneven distribution of pres- sure fluctuations around the circumference of volute. Besides the main frequency and its multiple frequency of pressure fluctuations in the centrifugal pump, the frequency caused by the long blades of complex impeller also plays a dominant role in the low-frequency areas. Furthermore, there exists biggish fluctuation phenomenon near the tongue. The composition of static pressure fluctuations frequency on the volute wall and blade outlet is similar except that the fluctuation amplitude near the volute wall reduces. In general, the different flow rates mainly have influence on the amplitude of fluctuation frequency in the pump, while have little effect on the frequency compo- sition.展开更多
With the horizontal Coriolis terms included in motion equations and the influence of compressibility of seawater on Brunt-Vaeisiaelae frequency considered, a numerical method of calculating the dispersion relation for...With the horizontal Coriolis terms included in motion equations and the influence of compressibility of seawater on Brunt-Vaeisiaelae frequency considered, a numerical method of calculating the dispersion relation for linear internal waves, which is an improvement of Cai and Gan （1995）, and hence Fliegel and Hunkins （1975）, had been set up. For different models （Pacific model, Atlantic model and Arctic model）, simulations using the three different methods were compared and the following conclusions were reached： （1） the influence of horizontal Coriolis terms on dispersion relation cannot be neglected and is connected with the direction of the wave celerity, the latitude, and the modes of the wave （2） the effect of compressibility of seawater in stratification is not an important factor for the dispersion relation of linear internal wave, at least for those three models, With the improved method, the wavefunction curves for the Pacific model had also been built.展开更多
基金supported by the National Natural Science Foundation of China granted No.51276172
文摘To investigate the unsteady flow characteristics in centrifugal pump, the flow field in a low-specific-speed centri- fugal pump with complex impeller is numerically simulated under different conditions. The RNG r-e turbulence model and sliding mesh are adopted during the process of computation. The results show that the interaction be- tween impeller and volute results in the unstable flow of the fluid, which causes the uneven distribution of pres- sure fluctuations around the circumference of volute. Besides the main frequency and its multiple frequency of pressure fluctuations in the centrifugal pump, the frequency caused by the long blades of complex impeller also plays a dominant role in the low-frequency areas. Furthermore, there exists biggish fluctuation phenomenon near the tongue. The composition of static pressure fluctuations frequency on the volute wall and blade outlet is similar except that the fluctuation amplitude near the volute wall reduces. In general, the different flow rates mainly have influence on the amplitude of fluctuation frequency in the pump, while have little effect on the frequency compo- sition.
基金the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-201).
文摘With the horizontal Coriolis terms included in motion equations and the influence of compressibility of seawater on Brunt-Vaeisiaelae frequency considered, a numerical method of calculating the dispersion relation for linear internal waves, which is an improvement of Cai and Gan （1995）, and hence Fliegel and Hunkins （1975）, had been set up. For different models （Pacific model, Atlantic model and Arctic model）, simulations using the three different methods were compared and the following conclusions were reached： （1） the influence of horizontal Coriolis terms on dispersion relation cannot be neglected and is connected with the direction of the wave celerity, the latitude, and the modes of the wave （2） the effect of compressibility of seawater in stratification is not an important factor for the dispersion relation of linear internal wave, at least for those three models, With the improved method, the wavefunction curves for the Pacific model had also been built.
