The low frequency oscillatory flow in a rotating curved pipe was studied by using the method of bi parameter perturbation. Perturbation solutions up to the second order were obtained and the effects of rotation on th...The low frequency oscillatory flow in a rotating curved pipe was studied by using the method of bi parameter perturbation. Perturbation solutions up to the second order were obtained and the effects of rotation on the low frequency oscillatory flow were examined in detail. The results indicated that there exists evident difference between the low frequency oscillatory flow in a rotating curved pipe and in a curved pipe without rotation. During a period, four secondary vortexes may exist on the circular cross section and the distribution of axial velocity and wall shear stress are related to the ratio of the Coriolis force to centrifugal force and the axial pressure gradient.展开更多
In this paper,we define lower-dimensional volumes of spin manifolds with boundary.We compute thelower-dimensional volume Vol^((2,2)) for 5-dimensional and 6-dimensional spin manifolds with boundary and we also getthe ...In this paper,we define lower-dimensional volumes of spin manifolds with boundary.We compute thelower-dimensional volume Vol^((2,2)) for 5-dimensional and 6-dimensional spin manifolds with boundary and we also getthe Kastler-Kalau-Walze type theorem in this case.展开更多
The characteristics of the dual bluff body vortex shedding is investigated, and the possibility to use dual bluff body combinations to strengthen the hydrodynamic vibration around the bluff body objects is explored. T...The characteristics of the dual bluff body vortex shedding is investigated, and the possibility to use dual bluff body combinations to strengthen the hydrodynamic vibration around the bluff body objects is explored. The numerical and experimental approaches were utilized to examine the time dependent flow field and the pressure oscillation around the bluff bodies. The numerical data were obtained by the advanced large eddy simulation model. The experiment was conducted on a laboratory scale of Karman vortex flowmeter with 40 mm diameter. It is revealed that the optimized dual bluff body combinations strengthened the hydrodynamic vibration. It was also found that the hydrodynamic vibration with 180° phase difference occurred at the axisymmetric points of circular pipe on the lateral faces of the equilateral triangle-section bluff bodies. Using the dual bluff body configuration and the differential sensing technique, a novel prototype of vortex flowmeter with excellent noise immunity and improved sensibility was developed.展开更多
In this paper, FLUENT software was used to simulate the burning process in a utility boiler. Chose the kinetics/diffusion-limited as combustion model, two-competing-rates as devolatilization model, RNG k-εmodel as vi...In this paper, FLUENT software was used to simulate the burning process in a utility boiler. Chose the kinetics/diffusion-limited as combustion model, two-competing-rates as devolatilization model, RNG k-εmodel as viscous model, and PDF model as combustion turbulent flow model. Numerical calculation of NOx formation in a 330 MW cyclone-opposed coal-fired utility boiler with 32 double air registers was done. The distribution characteristics of temperature, NOx and oxygen concentration in furnace were studied. They were symmetrically distributed in furnace. In the combustion area, temperature and NOx concentration are high, while oxygen concentration is low. Temperature and NOx concentration are declined gradually along with furnace height, while oxygen concentration is raised. The higher the temperature is and the greater the excess air coefficient is, the more NOx formation.展开更多
In this study, kinetic energy budget equations of rotational and divergent flow in pressure coordinates are derived on terrain-following coordinates. The new formulation explicitly shows the terrain effects and can be...In this study, kinetic energy budget equations of rotational and divergent flow in pressure coordinates are derived on terrain-following coordinates. The new formulation explicitly shows the terrain effects and can be applied directly to model-simulated dynamic and thermodynamic fields on the model's original vertical grid. Such application eliminates interpolation error and avoids errors in virtual weather systems in mountainous areas. These advantages and their significance are demonstrated by a numerical study in terrain-following coordinates of a developing vortex after it moves over the Tibetan Plateau in China.展开更多
文摘The low frequency oscillatory flow in a rotating curved pipe was studied by using the method of bi parameter perturbation. Perturbation solutions up to the second order were obtained and the effects of rotation on the low frequency oscillatory flow were examined in detail. The results indicated that there exists evident difference between the low frequency oscillatory flow in a rotating curved pipe and in a curved pipe without rotation. During a period, four secondary vortexes may exist on the circular cross section and the distribution of axial velocity and wall shear stress are related to the ratio of the Coriolis force to centrifugal force and the axial pressure gradient.
基金Supported by National Natural Science Foundation of China under Grant No.10801027Fok Ying Tong Education Foundation under Grant No.121003
文摘In this paper,we define lower-dimensional volumes of spin manifolds with boundary.We compute thelower-dimensional volume Vol^((2,2)) for 5-dimensional and 6-dimensional spin manifolds with boundary and we also getthe Kastler-Kalau-Walze type theorem in this case.
基金Supported by the National Natural Science Foundation of China (No. 59835160) and Scientific Research Foundation of State Education Ministry for Returned Overseas Chinese Scholars.
文摘The characteristics of the dual bluff body vortex shedding is investigated, and the possibility to use dual bluff body combinations to strengthen the hydrodynamic vibration around the bluff body objects is explored. The numerical and experimental approaches were utilized to examine the time dependent flow field and the pressure oscillation around the bluff bodies. The numerical data were obtained by the advanced large eddy simulation model. The experiment was conducted on a laboratory scale of Karman vortex flowmeter with 40 mm diameter. It is revealed that the optimized dual bluff body combinations strengthened the hydrodynamic vibration. It was also found that the hydrodynamic vibration with 180° phase difference occurred at the axisymmetric points of circular pipe on the lateral faces of the equilateral triangle-section bluff bodies. Using the dual bluff body configuration and the differential sensing technique, a novel prototype of vortex flowmeter with excellent noise immunity and improved sensibility was developed.
基金Supported by Major Project of Tackle Key Problems of Shanghai (Z2003-1)
文摘In this paper, FLUENT software was used to simulate the burning process in a utility boiler. Chose the kinetics/diffusion-limited as combustion model, two-competing-rates as devolatilization model, RNG k-εmodel as viscous model, and PDF model as combustion turbulent flow model. Numerical calculation of NOx formation in a 330 MW cyclone-opposed coal-fired utility boiler with 32 double air registers was done. The distribution characteristics of temperature, NOx and oxygen concentration in furnace were studied. They were symmetrically distributed in furnace. In the combustion area, temperature and NOx concentration are high, while oxygen concentration is low. Temperature and NOx concentration are declined gradually along with furnace height, while oxygen concentration is raised. The higher the temperature is and the greater the excess air coefficient is, the more NOx formation.
基金supported by the Key Program of the Chinese Academy of Sciences(No.KZZD-EW-05-01)the Supporting Program for Science and Technological Research of China(No.2008BAC37B01)+1 种基金the National Basic Research Program of China(Nos.2012CB417201 and 2009CB421505)the National Natural Sciences Foundation of China(Nos.41205033 and 41175056)
文摘In this study, kinetic energy budget equations of rotational and divergent flow in pressure coordinates are derived on terrain-following coordinates. The new formulation explicitly shows the terrain effects and can be applied directly to model-simulated dynamic and thermodynamic fields on the model's original vertical grid. Such application eliminates interpolation error and avoids errors in virtual weather systems in mountainous areas. These advantages and their significance are demonstrated by a numerical study in terrain-following coordinates of a developing vortex after it moves over the Tibetan Plateau in China.
