The effect of melt over-heating on the morphology of Al_9FeNi phase in 2618aluminum alloy with high contents of Fe and Ni and 0.22 wt. percent zirconium has been investigatedby optical microscopy. SEM and TEM. The mec...The effect of melt over-heating on the morphology of Al_9FeNi phase in 2618aluminum alloy with high contents of Fe and Ni and 0.22 wt. percent zirconium has been investigatedby optical microscopy. SEM and TEM. The mechanical properties of 2618 aluminum alloy after hotextrusion and quenching/aging have been tested. The results show: melt over-heating treatment of2618 alloy with high contents of Fe and Ni at 960 deg C led to finer and better-distributedneedle-like Al_9FeNi phase in cast microstructure and fine Al_9FeNi particles after hot extrusion;the grain size of the alloy after hot extrusion could also be refined evidently by alloying ofzirconium; the ambient and high temperature tensile strength and elongation of 2618 alloy have beenapparently enhanced due to fine Al_9FeNi particles and dispersed Al_3Zr as well as fine grain size.展开更多
The heat receiver is an essential part of the Concentrating Solar Power plant,directly affecting its operation and safety.In this paper,the Monte Carlo ray-tracing algorithm was introduced to evaluate a 50 MW(e)extern...The heat receiver is an essential part of the Concentrating Solar Power plant,directly affecting its operation and safety.In this paper,the Monte Carlo ray-tracing algorithm was introduced to evaluate a 50 MW(e)external cylindrical receiver’s thermal performance.The radiation heat flux concentrated from the heliostats field and the view factors between grids divided from the tubes were both calculated using Monte Carlo ray-tracing algorithm.Besides,an in-house code was developed and verified,including three modules of the view-factor calculation,thermal performance calculation,and thermal stress calculation.It was also employed to investigate the 50 MW(e)receiver,and the detailed 3D profiles of temperature and thermal stress in the receiver were analyzed.It was found that the molten salt was heated from 298℃to 565℃and the tube at the 50 MW(e)receiver’s outlet had a high temperature,while the high thermal stress came out at the receiver’s entrance.Finally,the over-temperature of the receiver was discussed,and an optimization algorithm was introduced.The tube wall temperature and film temperature at the overheated area matched the safety criteria,and the outlet molten salt temperature still reached 563℃after the optimization process,with only 2℃dropped.展开更多
The influence of a glow electrical discharge on the wake behind two cylinders was studied. This effect consists in a redistribution of the power in the velocity pulsation spectrum due to the discharge action on fluid ...The influence of a glow electrical discharge on the wake behind two cylinders was studied. This effect consists in a redistribution of the power in the velocity pulsation spectrum due to the discharge action on fluid flow. To treat this observation, we need a simple model of intermittent turbulent wake in the vicinity of cylinders. A variant of such model has been developed in the form of two coupled van-der-Pole oscillators representing two interacting von Karman vortex streets behind the cylinders. According to the model, the set of the global wake modes and its concurrence are discussed. Accordingly, a mechanism of the glow discharge effect on the cylinders wake has been proposed.展开更多
I.INTRODUCTION Aerosol is an important atmospheric pollutant. Because of different sources and complicated forming processes, its composition and contents vary widely. Some aerosols may be harmful if they contain elem...I.INTRODUCTION Aerosol is an important atmospheric pollutant. Because of different sources and complicated forming processes, its composition and contents vary widely. Some aerosols may be harmful if they contain elements which can induce cancer or heart diseases; some may become reaction beds or carriers of other pollutants. Thus the composition and con-展开更多
基金The present study was supported by the National Key Basic Research and Development Programme of China (Project No. G1999064909).
文摘The effect of melt over-heating on the morphology of Al_9FeNi phase in 2618aluminum alloy with high contents of Fe and Ni and 0.22 wt. percent zirconium has been investigatedby optical microscopy. SEM and TEM. The mechanical properties of 2618 aluminum alloy after hotextrusion and quenching/aging have been tested. The results show: melt over-heating treatment of2618 alloy with high contents of Fe and Ni at 960 deg C led to finer and better-distributedneedle-like Al_9FeNi phase in cast microstructure and fine Al_9FeNi particles after hot extrusion;the grain size of the alloy after hot extrusion could also be refined evidently by alloying ofzirconium; the ambient and high temperature tensile strength and elongation of 2618 alloy have beenapparently enhanced due to fine Al_9FeNi particles and dispersed Al_3Zr as well as fine grain size.
基金The Project is supported by the Innovative Research Groups of the National Natural Science Foundation of China(51621005).
文摘The heat receiver is an essential part of the Concentrating Solar Power plant,directly affecting its operation and safety.In this paper,the Monte Carlo ray-tracing algorithm was introduced to evaluate a 50 MW(e)external cylindrical receiver’s thermal performance.The radiation heat flux concentrated from the heliostats field and the view factors between grids divided from the tubes were both calculated using Monte Carlo ray-tracing algorithm.Besides,an in-house code was developed and verified,including three modules of the view-factor calculation,thermal performance calculation,and thermal stress calculation.It was also employed to investigate the 50 MW(e)receiver,and the detailed 3D profiles of temperature and thermal stress in the receiver were analyzed.It was found that the molten salt was heated from 298℃to 565℃and the tube at the 50 MW(e)receiver’s outlet had a high temperature,while the high thermal stress came out at the receiver’s entrance.Finally,the over-temperature of the receiver was discussed,and an optimization algorithm was introduced.The tube wall temperature and film temperature at the overheated area matched the safety criteria,and the outlet molten salt temperature still reached 563℃after the optimization process,with only 2℃dropped.
文摘The influence of a glow electrical discharge on the wake behind two cylinders was studied. This effect consists in a redistribution of the power in the velocity pulsation spectrum due to the discharge action on fluid flow. To treat this observation, we need a simple model of intermittent turbulent wake in the vicinity of cylinders. A variant of such model has been developed in the form of two coupled van-der-Pole oscillators representing two interacting von Karman vortex streets behind the cylinders. According to the model, the set of the global wake modes and its concurrence are discussed. Accordingly, a mechanism of the glow discharge effect on the cylinders wake has been proposed.
文摘I.INTRODUCTION Aerosol is an important atmospheric pollutant. Because of different sources and complicated forming processes, its composition and contents vary widely. Some aerosols may be harmful if they contain elements which can induce cancer or heart diseases; some may become reaction beds or carriers of other pollutants. Thus the composition and con-
