Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety a...Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.展开更多
Microresonator dispersion plays a crucial role in shaping the nonlinear dynamics of microcavity solitons.Here,we introduce and validate a method for dispersion engineering through modulating a portion of the inner edg...Microresonator dispersion plays a crucial role in shaping the nonlinear dynamics of microcavity solitons.Here,we introduce and validate a method for dispersion engineering through modulating a portion of the inner edge of ring waveguides.We demonstrate that such partial modulation has a broadband effect on the dispersion profile,whereas modulation on the entire resonator's inner circumference leads to mode splitting primarily affecting one optical mode.The impact of spatial modulation amplitude,period,and number of modulations on the mode splitting profile is also investigated.Through the integration of four modulated sections with different modulation amplitudes and periods,we achieve mode splitting across more than 50 modes over a spectral range exceeding 100 nm in silicon nitride resonators.These results highlight both the simplicity and efficacy of our method in achieving flatter dispersion profiles.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U2241240,12172045 and 12221002)the Opening Fund of State Key Laboratory of Explosion Science and Technology of Beijing Institute of Technology,China(No.ZDKT23-02)。
文摘Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.
基金European Research Council(756966)MaxPlanck-Gesellschaft+1 种基金H2020 Marie Sklodowska-Curie COFUND“Multiply”(713694)Marie Curie Innovative Training Network“Microcombs”(812818)。
文摘Microresonator dispersion plays a crucial role in shaping the nonlinear dynamics of microcavity solitons.Here,we introduce and validate a method for dispersion engineering through modulating a portion of the inner edge of ring waveguides.We demonstrate that such partial modulation has a broadband effect on the dispersion profile,whereas modulation on the entire resonator's inner circumference leads to mode splitting primarily affecting one optical mode.The impact of spatial modulation amplitude,period,and number of modulations on the mode splitting profile is also investigated.Through the integration of four modulated sections with different modulation amplitudes and periods,we achieve mode splitting across more than 50 modes over a spectral range exceeding 100 nm in silicon nitride resonators.These results highlight both the simplicity and efficacy of our method in achieving flatter dispersion profiles.
