The characteristics of pressure fluctuation in a sub me rged circulative impinging stream reactor (SCISR) were experimentally studied.Th e instantaneous signals of pressure fluctuation resulting from the turbulence in...The characteristics of pressure fluctuation in a sub me rged circulative impinging stream reactor (SCISR) were experimentally studied.Th e instantaneous signals of pressure fluctuation resulting from the turbulence in the SCISR were measured by sensors and recorded by a computer.The pressure sign als at some special positions were sampled at different rotary speeds of propell er.After analyzing the signals with the Power Spectrum method,it was found that there was an inherent frequency in the dynamic pressure signals.The inherent fr equencies of the point on the impinging plane were greater than 1000 Hz,so the pressure fluctuation was called high-frequency fluctuation.The fluctuation velo cities with high inherent frequency resulted in a strong shear force field,whic h enabled the fluid to mix quickly on the micro-scale and the agglomerates of s olid particles to disperse effectively.展开更多
The turbulent cavitating flow around the propelling pump tip clearance is numerically simulated using the large eddy simulation(LES)method coupled with the Zwart-Gerber-Belamri(ZGB)cavitation model to investigate the ...The turbulent cavitating flow around the propelling pump tip clearance is numerically simulated using the large eddy simulation(LES)method coupled with the Zwart-Gerber-Belamri(ZGB)cavitation model to investigate the cavitation-vortex interaction mechanism.The calculated cavitation structures around the blades are in a remarkable agreement with the experimental results.The distributions of the tip clearance vortex under two cavitation conditions are obtained and compared.The results show that the cavitation development enhances the vorticity generation and the flow unsteadiness around the tip clearance of a propelling pump.Vortices are basically located around the cavitation areas,particularly in the tip clearance region,during the cavitation.The relative vorticity transport equation is applied for the cavitating turbulent flows and it is further indicated that the vortex stretching term makes the main contribution in the vortex production,and the baroclinic torque and dilation terms are important source terms for the vorticity generation in the cavitating flow.In addition,the viscous diffusion term and the Coriolis force term are significant in modifying the vorticity field inside the blade tip clearance.展开更多
文摘The characteristics of pressure fluctuation in a sub me rged circulative impinging stream reactor (SCISR) were experimentally studied.Th e instantaneous signals of pressure fluctuation resulting from the turbulence in the SCISR were measured by sensors and recorded by a computer.The pressure sign als at some special positions were sampled at different rotary speeds of propell er.After analyzing the signals with the Power Spectrum method,it was found that there was an inherent frequency in the dynamic pressure signals.The inherent fr equencies of the point on the impinging plane were greater than 1000 Hz,so the pressure fluctuation was called high-frequency fluctuation.The fluctuation velo cities with high inherent frequency resulted in a strong shear force field,whic h enabled the fluid to mix quickly on the micro-scale and the agglomerates of s olid particles to disperse effectively.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51822903,11772239).
文摘The turbulent cavitating flow around the propelling pump tip clearance is numerically simulated using the large eddy simulation(LES)method coupled with the Zwart-Gerber-Belamri(ZGB)cavitation model to investigate the cavitation-vortex interaction mechanism.The calculated cavitation structures around the blades are in a remarkable agreement with the experimental results.The distributions of the tip clearance vortex under two cavitation conditions are obtained and compared.The results show that the cavitation development enhances the vorticity generation and the flow unsteadiness around the tip clearance of a propelling pump.Vortices are basically located around the cavitation areas,particularly in the tip clearance region,during the cavitation.The relative vorticity transport equation is applied for the cavitating turbulent flows and it is further indicated that the vortex stretching term makes the main contribution in the vortex production,and the baroclinic torque and dilation terms are important source terms for the vorticity generation in the cavitating flow.In addition,the viscous diffusion term and the Coriolis force term are significant in modifying the vorticity field inside the blade tip clearance.
