A boundary plasma turbulence code BOUT is presented. The preliminary encour- aging results have been obtained when comparing with probe measurements for a typical Ohmic discharge in HT-7 tokamak. The validation and be...A boundary plasma turbulence code BOUT is presented. The preliminary encour- aging results have been obtained when comparing with probe measurements for a typical Ohmic discharge in HT-7 tokamak. The validation and benchmark of BOUT code and experimental diagnostic tools for fusion boundary plasma turbulence is proposed.展开更多
This paper presents an experimental investigation of the circulation of the horseshoe vortex system within the equilibrium scour hole at a circular pier, with the data measured by an acoustic Doppler velocimeter （ADV...This paper presents an experimental investigation of the circulation of the horseshoe vortex system within the equilibrium scour hole at a circular pier, with the data measured by an acoustic Doppler velocimeter （ADV）. Velocity vector plots and vorticity contours of the flow field on the upstream plane of symmetry （y = 0 cm） and on the planes ：e3 cm away from the plane of symmetry Cv = ~3 cm） are presented. The vorticity and circulation of the horseshoe vortices were determined using the forward difference technique and Stokes theorem, respectively. The results show that the magnitudes of circulations are similar on the planes y = 3 cm and y = -3 cm, which are less than those on the plane y = 0 cm. The circulation decreases with the increase of flow shallowness, and increases with the densimetric Froude number. It also increases with the pier Reynolds number at a constant densimetric Froude number, or at a constant flow shallowness. The relative vortex strength （dimensionless circulation） decreases with the increase of the pier Reynolds number. Some empirical equations are proposed based on the results. The predicted circulation values with these equations match the measured data, which indicates that these equations can be used to estimate the circulation in future studies.展开更多
An extensive set of measurements in 2-D turbulent mixing layer, wake and jet flow by the hot-wire technique and data sampling are presented. The measured quantities, i. e. the mean velocity, the turbulence intensity, ...An extensive set of measurements in 2-D turbulent mixing layer, wake and jet flow by the hot-wire technique and data sampling are presented. The measured quantities, i. e. the mean velocity, the turbulence intensity, the Reynolds stress and higher-order correlations of the fluctuating velocity in the self-preserving region of the above free shear flows are compared with the computational results based on Zhou's theory for the shear turbulence of in- compressible fluid. The experimental and computational results are in good agreement.展开更多
This study deals with the turbulent structure in the surface layer over the Qinghai-Xizang Plateau.Using gradient transfer and heat balance methods we have determined the nondimensional coefficient 1/(?)_m(?)h in the ...This study deals with the turbulent structure in the surface layer over the Qinghai-Xizang Plateau.Using gradient transfer and heat balance methods we have determined the nondimensional coefficient 1/(?)_m(?)h in the expression of turbulent transfer coefficient for sensible heat (K_h).It is found that the results are in good agreement with the 1/(?)_m(?)_h obtained by Pruitt,et al.The K_h at a height of 1m under cloudy and cloudless conditions is calculated.Finally,the ratio of K_h to momentum turbulent coefficient over the plateau is compared with those over plains.展开更多
An experimental study on TBL (turbulent boundary layer) pressure fluctuation frequeny spectrum of a revolution body is presented. With the measured results, a relation of convective frequency fo of the models is...An experimental study on TBL (turbulent boundary layer) pressure fluctuation frequeny spectrum of a revolution body is presented. With the measured results, a relation of convective frequency fo of the models is obtained. Relations of turbuleat wall-pressure fluctuation spectrum in transition region and development region to frequency and speed are obtained also展开更多
基金Work performed under the auspices of the U. S. Department of Energy by University of California Lawrence LivermoreNational Lab
文摘A boundary plasma turbulence code BOUT is presented. The preliminary encour- aging results have been obtained when comparing with probe measurements for a typical Ohmic discharge in HT-7 tokamak. The validation and benchmark of BOUT code and experimental diagnostic tools for fusion boundary plasma turbulence is proposed.
文摘This paper presents an experimental investigation of the circulation of the horseshoe vortex system within the equilibrium scour hole at a circular pier, with the data measured by an acoustic Doppler velocimeter （ADV）. Velocity vector plots and vorticity contours of the flow field on the upstream plane of symmetry （y = 0 cm） and on the planes ：e3 cm away from the plane of symmetry Cv = ~3 cm） are presented. The vorticity and circulation of the horseshoe vortices were determined using the forward difference technique and Stokes theorem, respectively. The results show that the magnitudes of circulations are similar on the planes y = 3 cm and y = -3 cm, which are less than those on the plane y = 0 cm. The circulation decreases with the increase of flow shallowness, and increases with the densimetric Froude number. It also increases with the pier Reynolds number at a constant densimetric Froude number, or at a constant flow shallowness. The relative vortex strength （dimensionless circulation） decreases with the increase of the pier Reynolds number. Some empirical equations are proposed based on the results. The predicted circulation values with these equations match the measured data, which indicates that these equations can be used to estimate the circulation in future studies.
文摘An extensive set of measurements in 2-D turbulent mixing layer, wake and jet flow by the hot-wire technique and data sampling are presented. The measured quantities, i. e. the mean velocity, the turbulence intensity, the Reynolds stress and higher-order correlations of the fluctuating velocity in the self-preserving region of the above free shear flows are compared with the computational results based on Zhou's theory for the shear turbulence of in- compressible fluid. The experimental and computational results are in good agreement.
文摘This study deals with the turbulent structure in the surface layer over the Qinghai-Xizang Plateau.Using gradient transfer and heat balance methods we have determined the nondimensional coefficient 1/(?)_m(?)h in the expression of turbulent transfer coefficient for sensible heat (K_h).It is found that the results are in good agreement with the 1/(?)_m(?)_h obtained by Pruitt,et al.The K_h at a height of 1m under cloudy and cloudless conditions is calculated.Finally,the ratio of K_h to momentum turbulent coefficient over the plateau is compared with those over plains.
文摘An experimental study on TBL (turbulent boundary layer) pressure fluctuation frequeny spectrum of a revolution body is presented. With the measured results, a relation of convective frequency fo of the models is obtained. Relations of turbuleat wall-pressure fluctuation spectrum in transition region and development region to frequency and speed are obtained also
