A theoretical model for the instability of turbulent boundary layer over compliant surfaces is described. The investigation of instability is carried out from a time-asymptotic space-time perspective that classifies i...A theoretical model for the instability of turbulent boundary layer over compliant surfaces is described. The investigation of instability is carried out from a time-asymptotic space-time perspective that classifies instabilities as either convective or absolute. Results are compared against experimental observations of surface waves on elastic and viscoelastic compliant layers.展开更多
The stability characteristics of laminar boundary layers over compliant walls was studied by the linear theory.Unlike the previous authors,the coupled motion of the fluid and solid was required to sat- isfy the contin...The stability characteristics of laminar boundary layers over compliant walls was studied by the linear theory.Unlike the previous authors,the coupled motion of the fluid and solid was required to sat- isfy the continuity conditions of both the velocity and stress at the interface.Results of calculations show that as the speed ratio or density ratio exceeds a certain threshold value,the two types of unstable waves will no longer be distinguishable,and the tangential component of the disturbance stress is no longer negligi- ble.So the neglect of it,as the previous authors did,is unjustified.展开更多
Multi-element doped graphite, GBST1308 has been developed as a plasma facing material (PFM) for high heat flux components of the HT-7U device. The thermal performance of the material under steady-state (SS) high heat ...Multi-element doped graphite, GBST1308 has been developed as a plasma facing material (PFM) for high heat flux components of the HT-7U device. The thermal performance of the material under steady-state (SS) high heat flux was evaluated under actively cooling conditions, the specimens were mechanically joined to copper heat sink with supercarbon sheet as a compliant layer between the interfaces. The experiments have been performed in a facility of ACT (actively cooling test stand) with a 100 kW electron gun in order to test the suitability and the loading limit of such materials. The surface temperature and bulk temperature distribution of the specimens were investigated. The experimental results are very encouraging that when heat flux is not more than 6 MW/m2, the surface temperature of GBST1308 is less than 1000℃, which is the lowest, compared with IG-430U and even with CX-2002U (CFC); The primary results indicate that the mechanically-joined material system by such a proper design as thin tile, super compliant layer, GBST as a PFM and copper-alloy heat sink, can be used as divertor plates for HT-7U in the first phase.展开更多
The characteristics of the direct resonance of a turbulent boundary layer over the compliant wall is studied by the linear stability theory. The velocity profiles in the turbulent boundary layers are taken from Lee et...The characteristics of the direct resonance of a turbulent boundary layer over the compliant wall is studied by the linear stability theory. The velocity profiles in the turbulent boundary layers are taken from Lee et al′s experiments. The results of numerical computation confirm the exisence of the direct resonance in the turbulent boundary layer on compliant surfaces. The streamwise and spanwise wave numbers in the turbulent boundary layer over compliant surface are changed compared with those over the rigid surface for the same flow parameters. It is found that the principal effect of changing the characteristics of the resonance comes from the profile modified by the compliant surface.展开更多
The drag reduction of compliant surface is studied in a ship model tank.The re- sults of the measured drag of a flat plate model show that the compliant surface is capable of re- ducing drag in a certain range of spee...The drag reduction of compliant surface is studied in a ship model tank.The re- sults of the measured drag of a flat plate model show that the compliant surface is capable of re- ducing drag in a certain range of speeds,The maximum drag reduction is 15.7% when the com- pliant surface is merely on the one side of the plate.These results have confirmed the predicted characteristics of compliant surfaces.展开更多
文摘A theoretical model for the instability of turbulent boundary layer over compliant surfaces is described. The investigation of instability is carried out from a time-asymptotic space-time perspective that classifies instabilities as either convective or absolute. Results are compared against experimental observations of surface waves on elastic and viscoelastic compliant layers.
基金The project is supported by the National Natural Science Fundation of China.
文摘The stability characteristics of laminar boundary layers over compliant walls was studied by the linear theory.Unlike the previous authors,the coupled motion of the fluid and solid was required to sat- isfy the continuity conditions of both the velocity and stress at the interface.Results of calculations show that as the speed ratio or density ratio exceeds a certain threshold value,the two types of unstable waves will no longer be distinguishable,and the tangential component of the disturbance stress is no longer negligi- ble.So the neglect of it,as the previous authors did,is unjustified.
基金This work was supported by National Meg-Science Engineering Project of Chinese Gevernment.
文摘Multi-element doped graphite, GBST1308 has been developed as a plasma facing material (PFM) for high heat flux components of the HT-7U device. The thermal performance of the material under steady-state (SS) high heat flux was evaluated under actively cooling conditions, the specimens were mechanically joined to copper heat sink with supercarbon sheet as a compliant layer between the interfaces. The experiments have been performed in a facility of ACT (actively cooling test stand) with a 100 kW electron gun in order to test the suitability and the loading limit of such materials. The surface temperature and bulk temperature distribution of the specimens were investigated. The experimental results are very encouraging that when heat flux is not more than 6 MW/m2, the surface temperature of GBST1308 is less than 1000℃, which is the lowest, compared with IG-430U and even with CX-2002U (CFC); The primary results indicate that the mechanically-joined material system by such a proper design as thin tile, super compliant layer, GBST as a PFM and copper-alloy heat sink, can be used as divertor plates for HT-7U in the first phase.
文摘The characteristics of the direct resonance of a turbulent boundary layer over the compliant wall is studied by the linear stability theory. The velocity profiles in the turbulent boundary layers are taken from Lee et al′s experiments. The results of numerical computation confirm the exisence of the direct resonance in the turbulent boundary layer on compliant surfaces. The streamwise and spanwise wave numbers in the turbulent boundary layer over compliant surface are changed compared with those over the rigid surface for the same flow parameters. It is found that the principal effect of changing the characteristics of the resonance comes from the profile modified by the compliant surface.
基金The project is supported by the National Natural Science Foundation of China.
文摘The drag reduction of compliant surface is studied in a ship model tank.The re- sults of the measured drag of a flat plate model show that the compliant surface is capable of re- ducing drag in a certain range of speeds,The maximum drag reduction is 15.7% when the com- pliant surface is merely on the one side of the plate.These results have confirmed the predicted characteristics of compliant surfaces.
