In order to research the influence of liquid water content ( LWC ) on blade icing of wind turbine, a numerical simulation method for blade icing was established. The numerical simulation was based on low speed viscous...In order to research the influence of liquid water content ( LWC ) on blade icing of wind turbine, a numerical simulation method for blade icing was established. The numerical simulation was based on low speed viscous N-S equation. The trajectory equation of water droplets was established by Lagrangian method. The mass and energy conservation equations of the water droplets impacting on the surface of the blade were solved based on control body theory. Three sections along blade span wise of a 1.5 MW wind turbine were decided to simulate icing. Five kinds of LWC were selected for simulation including 0.2,0.4,0.6,0.8 and 1.0 g/m^3 under two ambient temperatures of -10 ℃ and -20 ℃. The medium volume droplet diameter ( MVD ) was 30μm. The simulations included icing shape on blade surface, dimensionless icing area and dimensionless maximum stagnation thickness. Furthermore, the flow fields around both the iced blade airfoil and the original one were simulated and analyzed. Accor-ding to the results, the typical icing characteristics of icing shape, icing area and thickness were greatly affected by the difference of LWCs. This study can provide theoretical reference for the research on antiicing and deicing of wind turbine blade.展开更多
Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separ...Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separation of hydrogen in the winding process, this article analyzed the reasons for above phenomena, established a numerical simulation model of winding process of above tube, using elastic-plastic Finite Element method analyzed the max. tensile stress and max. compression stress and their locations, thereby provides a theory base for the control of working forming course of thin wall spiral tube.展开更多
Wind barriers have attracted significant attention as an effective measure to ensure train safety under crosswinds.However,in past decades,the influence of structural parameters such as the height and ventilation rati...Wind barriers have attracted significant attention as an effective measure to ensure train safety under crosswinds.However,in past decades,the influence of structural parameters such as the height and ventilation ratio of wind barriers on the difference of the average pressure coefficient between the train windward and leeward surface(ΔCp)has not been fully investigated.To determine the influence of the interaction among the three factors,namely the wind barrier height(H),ventilation ratio(R),and distance to the train(D),twenty five numerical simulation cases with different structural parameters were considered based on an orthogonal design.The shear stress transfer(SST)k-ωturbulent model was employed to calculate the wind pressure coefficients,and the calculation accuracy was validated by using wind tunnel experiments.The results indicated that with an increase in R,ΔCp first decreased and then increased,andΔCp decreased while D increased.Moreover,with the increase in H,ΔCp first increased and then decreased.Therefore,these three factors must be considered during the installation of wind barriers.Furthermore,according to a range analysis(judging the relative importance of the three factors intuitively),the three factors were ranked in the following order:R>H>D.Based on a variance analysis,R was found to be of high significance toΔCp,followed by H,which was significant,whereas D had relatively insignificant influence.Finally,the optimal values of R and H were determined to be 20%and 110 mm,respectively.And when R=40%,H=85 mm,the train was relatively unsafe under these such conditions.The findings of this study provide significant guidance for the structural design of wind barriers.展开更多
基金sponsored by the projects supported by the National Natural Science Foundation of China(NSFC,No.51576037 and 11172314)the National Key Basic Research Program of China (2015CB755800)
文摘In order to research the influence of liquid water content ( LWC ) on blade icing of wind turbine, a numerical simulation method for blade icing was established. The numerical simulation was based on low speed viscous N-S equation. The trajectory equation of water droplets was established by Lagrangian method. The mass and energy conservation equations of the water droplets impacting on the surface of the blade were solved based on control body theory. Three sections along blade span wise of a 1.5 MW wind turbine were decided to simulate icing. Five kinds of LWC were selected for simulation including 0.2,0.4,0.6,0.8 and 1.0 g/m^3 under two ambient temperatures of -10 ℃ and -20 ℃. The medium volume droplet diameter ( MVD ) was 30μm. The simulations included icing shape on blade surface, dimensionless icing area and dimensionless maximum stagnation thickness. Furthermore, the flow fields around both the iced blade airfoil and the original one were simulated and analyzed. Accor-ding to the results, the typical icing characteristics of icing shape, icing area and thickness were greatly affected by the difference of LWCs. This study can provide theoretical reference for the research on antiicing and deicing of wind turbine blade.
文摘Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separation of hydrogen in the winding process, this article analyzed the reasons for above phenomena, established a numerical simulation model of winding process of above tube, using elastic-plastic Finite Element method analyzed the max. tensile stress and max. compression stress and their locations, thereby provides a theory base for the control of working forming course of thin wall spiral tube.
基金Project(51822803)supported by the National Natural Science Foundation of ChinaProject(2019JJ50688)supported by Hunan Provincial Natural Science Foundation,China+1 种基金Project(kq1905005)supported by Training Program for Excellent Young Innovators of Changsha,ChinaProject(CX20210775)supported by Hunan Provincial Innovative Foundation for Postgraduates,China。
文摘Wind barriers have attracted significant attention as an effective measure to ensure train safety under crosswinds.However,in past decades,the influence of structural parameters such as the height and ventilation ratio of wind barriers on the difference of the average pressure coefficient between the train windward and leeward surface(ΔCp)has not been fully investigated.To determine the influence of the interaction among the three factors,namely the wind barrier height(H),ventilation ratio(R),and distance to the train(D),twenty five numerical simulation cases with different structural parameters were considered based on an orthogonal design.The shear stress transfer(SST)k-ωturbulent model was employed to calculate the wind pressure coefficients,and the calculation accuracy was validated by using wind tunnel experiments.The results indicated that with an increase in R,ΔCp first decreased and then increased,andΔCp decreased while D increased.Moreover,with the increase in H,ΔCp first increased and then decreased.Therefore,these three factors must be considered during the installation of wind barriers.Furthermore,according to a range analysis(judging the relative importance of the three factors intuitively),the three factors were ranked in the following order:R>H>D.Based on a variance analysis,R was found to be of high significance toΔCp,followed by H,which was significant,whereas D had relatively insignificant influence.Finally,the optimal values of R and H were determined to be 20%and 110 mm,respectively.And when R=40%,H=85 mm,the train was relatively unsafe under these such conditions.The findings of this study provide significant guidance for the structural design of wind barriers.
