Based on the characteristics of large flow rate , low head , short annual operation time , and high reliability of the city flood-control pumping stations , a new-type shaft tubular pumping system featuring a shaft su...Based on the characteristics of large flow rate , low head , short annual operation time , and high reliability of the city flood-control pumping stations , a new-type shaft tubular pumping system featuring a shaft suction box and a siphon-type discharge passage with a vacuum breaker as the cutoff device was developed , which possesses such advantages as simple structure , reliable cutoff , and high energy performance.Taking some pumping stations as the case studies , in the light of the specified operation conditions , the hydraulic optimal design of the shaft-type tubular pumping system was determined and the optimized shape of the system was recommended.The performance prediction based on the computational fluid dynamics methodology was determined and the model test verification was conducted.The results show that the predicted data agree with the experimental head and efficiency so that both methods can be used to determine the performance of a real pumping station.Finally , the in-situ measurements of a pumping station during the commissioning period further verified that the shaft-type tubular pumping station with a siphon discharge passage is of higher efficiency , more reliable and stable.展开更多
Numerical simulation was used to estimate the temperature field within a poured concrete,mono-layer freezing-shaft lining.The affects from various factors were investigated.The maximum temperature within the lining in...Numerical simulation was used to estimate the temperature field within a poured concrete,mono-layer freezing-shaft lining.The affects from various factors were investigated.The maximum temperature within the lining increases as the lining thickness increases,decreases as the soil-side wall temperature decreases,decreases as the air temperature inside the shaft decreases and decreases as the air velocity inside the shaft increases.The compression speed of an insulating foam layer affects the maximum temperature difference between the interior and the sidewalls.The maximum temperature difference between the interior and the sidewalls approaches or exceeds the maximum allowable for the curing of poured concrete structures.Attention should be paid to the question of the lining cracking during the curing period.The temperature gradient in the vertical direction may be minimized by preventing air contact against the steel connection board supporting the base of the freshly poured section.展开更多
Free translation caused by attractive field-gradient force was observed for Ni and ferrite(CuFe_2O_4) grains that were released in a diffuse area.In order to exclude the effect of terrestrial gravity,translation was o...Free translation caused by attractive field-gradient force was observed for Ni and ferrite(CuFe_2O_4) grains that were released in a diffuse area.In order to exclude the effect of terrestrial gravity,translation was observed in micro-gravity(μG) condition produced by a compact drop-shaft installed in a ordinary laboratory room.Magnetization Ms per unit mass of the grain is obtained by analyzing the above-mentioned translations in terms of a energy conservation rule;here conservation of the sum of field-induced potential mMsH and kinetic energy 1/2/mv^2 is considered for a particle with mass m.The present method of obtaining Ms is free of measuring the mass of sample;this is because the field-gradient force is a volume force that is proportional to m.The method is also free of an interfering signal emitted from the sample holder.Accordingly,Ms is detectable irrespective of sample size,provided that the field-induced translation is observable.The above-mentioned procedure to estimate Ms from filed-induced translation is a step to obtain a reliable magnetic data from a single nano-sized grain.The efficiency of material identification was recently confirmed on various solid grains,which was based on diamagnetic magnetization data obtained from its translations caused by field-gradient repulsive force.A diamagnetic material generally possesses an intrinsic value of magnetic susceptibility and its anisotropy.The present results on nickel grains indicate that the principle of material identification based on its magnetization data is applicable for the three major category of magnetic materials,namely ferro-(or ferri-) magnetic, paramagnetic and diamagnetic material.展开更多
基金support by the 11th Five Year Key Project of China’s National Scientific Supporting Plan(Grant No.2006BAB04A03)the Hydraulic Engineering Project from the Water Resources Department of Jiangsu Province(Grant No.2010023)
文摘Based on the characteristics of large flow rate , low head , short annual operation time , and high reliability of the city flood-control pumping stations , a new-type shaft tubular pumping system featuring a shaft suction box and a siphon-type discharge passage with a vacuum breaker as the cutoff device was developed , which possesses such advantages as simple structure , reliable cutoff , and high energy performance.Taking some pumping stations as the case studies , in the light of the specified operation conditions , the hydraulic optimal design of the shaft-type tubular pumping system was determined and the optimized shape of the system was recommended.The performance prediction based on the computational fluid dynamics methodology was determined and the model test verification was conducted.The results show that the predicted data agree with the experimental head and efficiency so that both methods can be used to determine the performance of a real pumping station.Finally , the in-situ measurements of a pumping station during the commissioning period further verified that the shaft-type tubular pumping station with a siphon discharge passage is of higher efficiency , more reliable and stable.
基金provided by the Office of National Science and Technology (No.2006BAB16B01)the Physics Program of the Henan Province Education Department (No.2009B 560004)the Doctoral Fund of Henan Polytechnic University (No.648234)
文摘Numerical simulation was used to estimate the temperature field within a poured concrete,mono-layer freezing-shaft lining.The affects from various factors were investigated.The maximum temperature within the lining increases as the lining thickness increases,decreases as the soil-side wall temperature decreases,decreases as the air temperature inside the shaft decreases and decreases as the air velocity inside the shaft increases.The compression speed of an insulating foam layer affects the maximum temperature difference between the interior and the sidewalls.The maximum temperature difference between the interior and the sidewalls approaches or exceeds the maximum allowable for the curing of poured concrete structures.Attention should be paid to the question of the lining cracking during the curing period.The temperature gradient in the vertical direction may be minimized by preventing air contact against the steel connection board supporting the base of the freshly poured section.
文摘Free translation caused by attractive field-gradient force was observed for Ni and ferrite(CuFe_2O_4) grains that were released in a diffuse area.In order to exclude the effect of terrestrial gravity,translation was observed in micro-gravity(μG) condition produced by a compact drop-shaft installed in a ordinary laboratory room.Magnetization Ms per unit mass of the grain is obtained by analyzing the above-mentioned translations in terms of a energy conservation rule;here conservation of the sum of field-induced potential mMsH and kinetic energy 1/2/mv^2 is considered for a particle with mass m.The present method of obtaining Ms is free of measuring the mass of sample;this is because the field-gradient force is a volume force that is proportional to m.The method is also free of an interfering signal emitted from the sample holder.Accordingly,Ms is detectable irrespective of sample size,provided that the field-induced translation is observable.The above-mentioned procedure to estimate Ms from filed-induced translation is a step to obtain a reliable magnetic data from a single nano-sized grain.The efficiency of material identification was recently confirmed on various solid grains,which was based on diamagnetic magnetization data obtained from its translations caused by field-gradient repulsive force.A diamagnetic material generally possesses an intrinsic value of magnetic susceptibility and its anisotropy.The present results on nickel grains indicate that the principle of material identification based on its magnetization data is applicable for the three major category of magnetic materials,namely ferro-(or ferri-) magnetic, paramagnetic and diamagnetic material.
