The incorporation of fluorine(F_(2)) into hydrogen-air(H_(2)/Air) mixtures presents a novel approach to enhancing the performance of rotating detonation engines(RDEs). This study systematically investigates the effect...The incorporation of fluorine(F_(2)) into hydrogen-air(H_(2)/Air) mixtures presents a novel approach to enhancing the performance of rotating detonation engines(RDEs). This study systematically investigates the effects of F_(2)concentration and inlet mass flow rate on rotating detonation wave(RDW) propagation using two-dimensional numerical simulations, providing the first comprehensive analysis of F_(2)as an oxidizing additive in regulating detonation performance, propagation stability, and heat release dynamics in RDEs. The results indicate that when F_(2)concentration is below 1%, the flow field primarily exhibits a stable single-wave propagation mode. As F_(2)concentration increases, RDW performance initially improves but then deteriorates, reaching its optimal state at 0.8% F_(2). When F_(2)concentration exceeds 1%, the coupled effects of F_(2)concentration and inlet mass flow rate induce a transition from single-wave to multi-wave propagation modes. While a higher inlet mass flow rate promotes increased wave numbers, it also intensifies wave-wave interactions. With further increases in F_(2)concentration, the enhanced heat release leads to intensified local deflagration, frequent hotspot formation, and wave collisions, ultimately degrading RDW performance and destabilizing the multi-wave flow field. Moreover, excessive HF formation is identified as a critical driver of enhanced deflagration, hotspot generation,and the disruption of multi-wave stability. These findings provide a theoretical foundation for integrating F_(2)additives into H_(2)/Air-based RDE systems.展开更多
An improved single image dehazing method based on dark channel prior and wavelet transform is proposed. This pro-posed method employs wavelet transform and guided filter instead of the soft matting procedure to estima...An improved single image dehazing method based on dark channel prior and wavelet transform is proposed. This pro-posed method employs wavelet transform and guided filter instead of the soft matting procedure to estimate and refine the depth map of haze images. Moreover, a contrast enhancement method based on just noticeable difference （JND） and quadratic function is adopted to enhance the contrast for the dehazed image, since the scene radiance is usual y not as bright as the atmospheric light, and the dehazed image looks dim. The experimental results show that the proposed approach can effectively enhance the haze ima-ge and is wel suitable for implementing on the surveil ance and obstacle detection systems.展开更多
文摘The incorporation of fluorine(F_(2)) into hydrogen-air(H_(2)/Air) mixtures presents a novel approach to enhancing the performance of rotating detonation engines(RDEs). This study systematically investigates the effects of F_(2)concentration and inlet mass flow rate on rotating detonation wave(RDW) propagation using two-dimensional numerical simulations, providing the first comprehensive analysis of F_(2)as an oxidizing additive in regulating detonation performance, propagation stability, and heat release dynamics in RDEs. The results indicate that when F_(2)concentration is below 1%, the flow field primarily exhibits a stable single-wave propagation mode. As F_(2)concentration increases, RDW performance initially improves but then deteriorates, reaching its optimal state at 0.8% F_(2). When F_(2)concentration exceeds 1%, the coupled effects of F_(2)concentration and inlet mass flow rate induce a transition from single-wave to multi-wave propagation modes. While a higher inlet mass flow rate promotes increased wave numbers, it also intensifies wave-wave interactions. With further increases in F_(2)concentration, the enhanced heat release leads to intensified local deflagration, frequent hotspot formation, and wave collisions, ultimately degrading RDW performance and destabilizing the multi-wave flow field. Moreover, excessive HF formation is identified as a critical driver of enhanced deflagration, hotspot generation,and the disruption of multi-wave stability. These findings provide a theoretical foundation for integrating F_(2)additives into H_(2)/Air-based RDE systems.
基金This research was supported by the Natural Science Foundation of Fujian Province under Grant Nos. 2015J01012 and 2015J01019.
文摘An improved single image dehazing method based on dark channel prior and wavelet transform is proposed. This pro-posed method employs wavelet transform and guided filter instead of the soft matting procedure to estimate and refine the depth map of haze images. Moreover, a contrast enhancement method based on just noticeable difference （JND） and quadratic function is adopted to enhance the contrast for the dehazed image, since the scene radiance is usual y not as bright as the atmospheric light, and the dehazed image looks dim. The experimental results show that the proposed approach can effectively enhance the haze ima-ge and is wel suitable for implementing on the surveil ance and obstacle detection systems.
