The experimental test of co-incinerating Chinese raw municipal solid waste （MSW） and coal in a laboratory-scale tubular reactor was first reported in present study, and the emission of normal gas components and the ...The experimental test of co-incinerating Chinese raw municipal solid waste （MSW） and coal in a laboratory-scale tubular reactor was first reported in present study, and the emission of normal gas components and the effects of the S/Cl molar ratio or coal mixing percentages on polychlorinated dibenzo-p-dioxins and dibenzofurans （PCDDs/Fs） emission were investigated and discussed. The results indicated that OCDD was the only PCDD homologues since others like TCDD-HpCDD was hardly detected, while as the categories of PCDF homologues were comparatively much more general. The amount of PCDD was much larger than that of PCDF in all operating conditions. Since ZPCDF/∑PCDD〈〈1, the dominant role of the precursor formation was proven in our experimental conductions. With increasing the coal addition to MSW （from 0 to 16%）, PCDD and PCDF were reduced considerably. Coal and MSW may suppress the PCDD/F emissions efficiently （over 95%） during the MSW incineration process. The PCDD/F suppression results of the present study could be helpful guidance to the industrial application of Chinese MSW and auxiliary coal co-incineration processes. The PCDD/F stack emission data of two industrial incinerators using co-incineration technology in China seem to have a great positive reduction of PCDDs/Fs.展开更多
Cavitation caused vibration and noise of hydraulic machinery. To some extent,cavitation made fatigue damage in advance. Many scholars found that the re-entrant jets were the reasons of the shedding of cavities. To sup...Cavitation caused vibration and noise of hydraulic machinery. To some extent,cavitation made fatigue damage in advance. Many scholars found that the re-entrant jets were the reasons of the shedding of cavities. To suppress cavitation,based on the idea of blocking the re-entrant jets,a special surface flow structure of 2D hydrofoil was proposed. The through-hole was made in the proper position of the hydrofoil. The incoming flow can outflow from this jet-hole automatically depending on the pressure difference between pressure side and suction side. Re-entrant jet growth can be weakened by optimizing the jet-hole geometry. Based on the standard k-ε turbulence model and Schnerr & Sauer cavitation model,under different cavitation numbers( σ) and jet-angles( β) for NACA0066( 2D) hydrofoil with 8° angles of attack,cavitation field numerical analysis was carried out. The results show that 2D hydrofoil cavitation flow had a strong unsteadiness. Making a jet-hole at the junction between the re-entrant jet and cavity can effectively minimize cloud cavitation. For a certain cavitation condition,optimal jet-angles( β) can be obtained to control cavitation growth. For the same β,the effects of cavitation suppression were changed with different cavitation numbers( σ). Consequently,suitable jet-angle and jet-position could extend the stable operating range of the hydrofoil.展开更多
To study the effectiveness of hydrofoil surface water injection on cavitation suppression,the unsteady cavitation flow field around the NACA0066 hydrofoil at attack angle of 6°was simulated by the modified RNG k-...To study the effectiveness of hydrofoil surface water injection on cavitation suppression,the unsteady cavitation flow field around the NACA0066 hydrofoil at attack angle of 6°was simulated by the modified RNG k-εturbulence model combined with the full-cavitation model.The structure of cavitation flow field and the hydrodynamic performance of hydrofoil were analyzed at the cavitation number of 0.85,0.70,0.55,respectively.The results show that barriered by the jet,the momentum of the reentrant jet was reduced;The development of cavitation and the strength of cavity shedding were weakened to some extent.Cavitation suppression effect was very obvious in the cavitation conditions with the cavitation number of 0.7 and above when the injection position was at 37% chord length from the hydrofoil leading edge and the jet-flow ratio kept 0.3.Time-averaged lift and drag coefficient were reduced,and the lift-drag ratio increased in water injection conditions.展开更多
Conventional scan-to-scan integration correlation （SIC） algorithms can detect small and stationary targets. However, they are ineffective in detecting small and fast-moving targets. This paper presents an improved S...Conventional scan-to-scan integration correlation （SIC） algorithms can detect small and stationary targets. However, they are ineffective in detecting small and fast-moving targets. This paper presents an improved SIC algorithm together with clutter suppression measures that remove or decrease sea clutter. The algorithm divides the scan-to-scan integration （SI） into two branches, one provides optimum clutter attenuation by means of SI weighting while the other ensures that targets are detected even if they are fast-moving. Sea clutter suppression can lower detection thre-sholds and, at the same time, increase signal-to-clutter ratio. Simulation results show that the proposed approach greatly improves the detection capability for warship radar.展开更多
基金Project supported by the National Basic Research Program (973) of China(No.G1999022211)the National Natural Science Foun-dation of China(No.59836210).
文摘The experimental test of co-incinerating Chinese raw municipal solid waste （MSW） and coal in a laboratory-scale tubular reactor was first reported in present study, and the emission of normal gas components and the effects of the S/Cl molar ratio or coal mixing percentages on polychlorinated dibenzo-p-dioxins and dibenzofurans （PCDDs/Fs） emission were investigated and discussed. The results indicated that OCDD was the only PCDD homologues since others like TCDD-HpCDD was hardly detected, while as the categories of PCDF homologues were comparatively much more general. The amount of PCDD was much larger than that of PCDF in all operating conditions. Since ZPCDF/∑PCDD〈〈1, the dominant role of the precursor formation was proven in our experimental conductions. With increasing the coal addition to MSW （from 0 to 16%）, PCDD and PCDF were reduced considerably. Coal and MSW may suppress the PCDD/F emissions efficiently （over 95%） during the MSW incineration process. The PCDD/F suppression results of the present study could be helpful guidance to the industrial application of Chinese MSW and auxiliary coal co-incineration processes. The PCDD/F stack emission data of two industrial incinerators using co-incineration technology in China seem to have a great positive reduction of PCDDs/Fs.
基金supported by the National Key Basic Research Special Foundation of China (2015CB057301)
文摘Cavitation caused vibration and noise of hydraulic machinery. To some extent,cavitation made fatigue damage in advance. Many scholars found that the re-entrant jets were the reasons of the shedding of cavities. To suppress cavitation,based on the idea of blocking the re-entrant jets,a special surface flow structure of 2D hydrofoil was proposed. The through-hole was made in the proper position of the hydrofoil. The incoming flow can outflow from this jet-hole automatically depending on the pressure difference between pressure side and suction side. Re-entrant jet growth can be weakened by optimizing the jet-hole geometry. Based on the standard k-ε turbulence model and Schnerr & Sauer cavitation model,under different cavitation numbers( σ) and jet-angles( β) for NACA0066( 2D) hydrofoil with 8° angles of attack,cavitation field numerical analysis was carried out. The results show that 2D hydrofoil cavitation flow had a strong unsteadiness. Making a jet-hole at the junction between the re-entrant jet and cavity can effectively minimize cloud cavitation. For a certain cavitation condition,optimal jet-angles( β) can be obtained to control cavitation growth. For the same β,the effects of cavitation suppression were changed with different cavitation numbers( σ). Consequently,suitable jet-angle and jet-position could extend the stable operating range of the hydrofoil.
基金National Key Basic Research Special Foundation of China(2015CB057301)
文摘To study the effectiveness of hydrofoil surface water injection on cavitation suppression,the unsteady cavitation flow field around the NACA0066 hydrofoil at attack angle of 6°was simulated by the modified RNG k-εturbulence model combined with the full-cavitation model.The structure of cavitation flow field and the hydrodynamic performance of hydrofoil were analyzed at the cavitation number of 0.85,0.70,0.55,respectively.The results show that barriered by the jet,the momentum of the reentrant jet was reduced;The development of cavitation and the strength of cavity shedding were weakened to some extent.Cavitation suppression effect was very obvious in the cavitation conditions with the cavitation number of 0.7 and above when the injection position was at 37% chord length from the hydrofoil leading edge and the jet-flow ratio kept 0.3.Time-averaged lift and drag coefficient were reduced,and the lift-drag ratio increased in water injection conditions.
文摘Conventional scan-to-scan integration correlation （SIC） algorithms can detect small and stationary targets. However, they are ineffective in detecting small and fast-moving targets. This paper presents an improved SIC algorithm together with clutter suppression measures that remove or decrease sea clutter. The algorithm divides the scan-to-scan integration （SI） into two branches, one provides optimum clutter attenuation by means of SI weighting while the other ensures that targets are detected even if they are fast-moving. Sea clutter suppression can lower detection thre-sholds and, at the same time, increase signal-to-clutter ratio. Simulation results show that the proposed approach greatly improves the detection capability for warship radar.
