According to fluid dynamics analysis during the fire, the criteria k-ε two-equation model for solving three-dimensional turbulence was determined, the pollutants generated in the fire disaster were set by adopting Mi...According to fluid dynamics analysis during the fire, the criteria k-ε two-equation model for solving three-dimensional turbulence was determined, the pollutants generated in the fire disaster were set by adopting Mixture multiphase flow, and the SIMPLE algorithm was used for solving on the basis of comprehensive consideration on the heat radia- tion and components transmission during fire. By simulating the airflow flowing state inside the tunnel during fire disaster of downward ventilation, drift ventilation, and ascensional ventilation, respectively, with regard to the actual situation of No.l, No.3, and No.5 belt roadway in Kongzhuang Coal Mine, the velocity vector distributions of pollutants under different inlet air volumes were obtained, and the damage degree and influential factors of disaster were also clear, which is helpful to control and avoid disaster during belt roadway fire.展开更多
At the interface between the lower atmosphere and sea surface,sea spray might significantly influence air-sea heat fluxes and subsequently,modulate upper ocean temperature during a typhoon passage. The effects of sea ...At the interface between the lower atmosphere and sea surface,sea spray might significantly influence air-sea heat fluxes and subsequently,modulate upper ocean temperature during a typhoon passage. The effects of sea spray were introduced into the parameterization of sea surface roughness in a 1-D turbulent model,to investigate the effects of sea spray on upper ocean temperature in the Kuroshio Extension area,for the cases of two real typhoons from 2006,Yagi and Soulik. Model output was compared with data from the Kuroshio Extension Observatory(KEO),and Reynolds and AMSRE satellite remote sensing sea surface temperatures. The results indicate drag coefficients that include the spray effect are closer to observations than those without,and that sea spray can enhance the heat fluxes(especially latent heat flux) considerably during a typhoon passage. Consequently,the model results with heat fluxes enhanced by sea spray simulate better the cooling process of the SST and upper-layer temperature profiles. Additionally,results from the simulation of the passage of typhoon Soulik(that passed KEO quickly),which included the sea spray effect,were better than for the simulated passage of typhoon Yagi(that crossed KEO slowly). These promising 1-D results could provide insight into the application of sea spray in general circulation models for typhoon studies.展开更多
Effects of the inlet guide vanes on the static characteristics, aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work. The inlet guide vanes with different outlet angle...Effects of the inlet guide vanes on the static characteristics, aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work. The inlet guide vanes with different outlet angle are designed, which are mounted on the casing and located at the upstream of the impeller of the prototype fan. Both steady and unsteady flow simulations arc performed. The steady flow is simulated by the calculations of Navier-Stokes equa- tions coupled with RNG k-epsilon turbulence model, while the unsteady flow is computed with large eddy simu- lation. According to the theoretical analysis, the inlet guide vanes with outlet angle of 60° are regarded as the op- timal inlet guide vanes. The static characteristic experiment is carried out in a standard test rig and the aerody- namic noise is tested in a semi-anechoic room. Then, performances of the fan with optimal inlet guide vanes are compared with those of the prototype fan. The results show that there is reasonable agreement between the simu- lation results and the experimental data. It is found that the static characteristics of small axial flow fan is im- proved obviously after installing the optimal inlet guide vanes. Meanwhile, the optimal inlet guide vanes have effect on reducing noise at the near field, but have little effect on the noise at the far field.展开更多
基金Supported by the International Science and Technology Cooperation Projects(2009DFA71840)Basic Research Business Projects of China Academy of Safety Science and Technology(2009JBKY07)
文摘According to fluid dynamics analysis during the fire, the criteria k-ε two-equation model for solving three-dimensional turbulence was determined, the pollutants generated in the fire disaster were set by adopting Mixture multiphase flow, and the SIMPLE algorithm was used for solving on the basis of comprehensive consideration on the heat radia- tion and components transmission during fire. By simulating the airflow flowing state inside the tunnel during fire disaster of downward ventilation, drift ventilation, and ascensional ventilation, respectively, with regard to the actual situation of No.l, No.3, and No.5 belt roadway in Kongzhuang Coal Mine, the velocity vector distributions of pollutants under different inlet air volumes were obtained, and the damage degree and influential factors of disaster were also clear, which is helpful to control and avoid disaster during belt roadway fire.
基金Supported by the National Basic Research Program of China(973 Program)(No.2013CB430304)the National Natural Science Foundation of China(Nos.41030854,41106005,41176003,41206178,41376015,41376013,41306006)+1 种基金the National High-Tech R&D Program of China(No.2013AA09A505)the Public Science and Technology Research Funds Projects of Ocean(No.20130531-8)
文摘At the interface between the lower atmosphere and sea surface,sea spray might significantly influence air-sea heat fluxes and subsequently,modulate upper ocean temperature during a typhoon passage. The effects of sea spray were introduced into the parameterization of sea surface roughness in a 1-D turbulent model,to investigate the effects of sea spray on upper ocean temperature in the Kuroshio Extension area,for the cases of two real typhoons from 2006,Yagi and Soulik. Model output was compared with data from the Kuroshio Extension Observatory(KEO),and Reynolds and AMSRE satellite remote sensing sea surface temperatures. The results indicate drag coefficients that include the spray effect are closer to observations than those without,and that sea spray can enhance the heat fluxes(especially latent heat flux) considerably during a typhoon passage. Consequently,the model results with heat fluxes enhanced by sea spray simulate better the cooling process of the SST and upper-layer temperature profiles. Additionally,results from the simulation of the passage of typhoon Soulik(that passed KEO quickly),which included the sea spray effect,were better than for the simulated passage of typhoon Yagi(that crossed KEO slowly). These promising 1-D results could provide insight into the application of sea spray in general circulation models for typhoon studies.
基金supported by National Natural Science Foundation of China No.51276172Public Welfare Technology Application Projects of Zhejiang Province NO.2015C31002Open Foundation of Zhejiang Provincial Top Key Academic Discipline of Mechanical Engineering and ZSTUMEOIA04 and 2013TD18
文摘Effects of the inlet guide vanes on the static characteristics, aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work. The inlet guide vanes with different outlet angle are designed, which are mounted on the casing and located at the upstream of the impeller of the prototype fan. Both steady and unsteady flow simulations arc performed. The steady flow is simulated by the calculations of Navier-Stokes equa- tions coupled with RNG k-epsilon turbulence model, while the unsteady flow is computed with large eddy simu- lation. According to the theoretical analysis, the inlet guide vanes with outlet angle of 60° are regarded as the op- timal inlet guide vanes. The static characteristic experiment is carried out in a standard test rig and the aerody- namic noise is tested in a semi-anechoic room. Then, performances of the fan with optimal inlet guide vanes are compared with those of the prototype fan. The results show that there is reasonable agreement between the simu- lation results and the experimental data. It is found that the static characteristics of small axial flow fan is im- proved obviously after installing the optimal inlet guide vanes. Meanwhile, the optimal inlet guide vanes have effect on reducing noise at the near field, but have little effect on the noise at the far field.
