The orientation strategy of side pipe and the heat transfer performance of six ground heat exchangers(GHEs) were optimized by numerical simulation,with soil being treated as a porous medium.An experiment on the heat t...The orientation strategy of side pipe and the heat transfer performance of six ground heat exchangers(GHEs) were optimized by numerical simulation,with soil being treated as a porous medium.An experiment on the heat transfer of four GHEs was carried out in 2010.Results indicate that the velocity field is disturbed by GHEs.The optimal orientation strategy of side pipe is that the upward pipe is located upstream and the downward pipe downstream.The space between GHEs should be appropriately adjusted,depending on the direction and flow velocity.Groups of GHEs should be installed perpendicular to the mainstream in a single row,but if the acreage does not meet the requirements,GHEs should be installed in staggered multiple rows.Fewer GHEs parallel to the mainstream strengthen the heat transfer.Moreover,numerical results agree well with the test data,with the maximum relative error being less than 7.7%.展开更多
This study aimed to conduct statistical analysis of temperature,relative humidity,wind direction,wind velocity,deep ground temperature and other related data from National Meteorological Observing Station of Hejian Ci...This study aimed to conduct statistical analysis of temperature,relative humidity,wind direction,wind velocity,deep ground temperature and other related data from National Meteorological Observing Station of Hejian City in 2012.According to the results,observation data varied due to different instruments and equipments,surrounding environments and underlying surface properties.The difference value of monthly average temperature between new site and old site ranged from-0.5 to 0 ℃; the difference value of monthly average maximum temperature ranged from-0.4 to 0.2 ℃; the difference value of monthly average minimum temperature ranged from-0.8 to 0 ℃; the difference value of monthly extreme maximum temperature ranged from-1.1 to 0.6 ℃; the difference value of monthly extreme minimum temperature ranged from-1.2 to 0.3 ℃.Annual average temperature,annual average maximum temperature and annual average minimum temperature in new site were lower than those in old site; annual extreme maximum temperature in new site was higher than that in old site; annual extreme minimum temperature in new site was lower than that in old site.The difference value of monthly average relative humidity between new site and old site ranged from 2％ to 6％; the difference value of monthly minimum relative humidity ranged from-4％ to 5％.Annual minimum relative humidity in new site was consistent with that in old site.The difference value of 2 min average wind velocity between new site and old site ranged from-0.1 to 0.4 m/s; the difference value of monthly maximum wind velocity ranged from-1.2 to 2.2 m/s; the difference value of monthly extreme wind velocity ranged from-2.0 to 2.8 m/s.Annual maximum wind velocity in new site was basically consistent with that in old site; annual extreme wind velocity in new site was significantly higher than that in old site; annual wind direction frequency in new site was lower than that in old site; annual most frequent wind direction in new site was S and that in old site was SSW.The difference value of average temperature at the depth of 40 cm ranged from-1.1 to 2.5 ℃; the difference value of average temperature at the depth of 80 cm ranged from-2.4 to 2.1 ℃; the difference value of average temperature at the depth of 160 cm ranged from-2.5 to 2.7 ℃; the difference value of average temperature at the depth of 320 cm ranged from-1.6 to 1.1 ℃.Annual average temperatures at the depths of 40 and 160 cm in new site were higher than those in old site,while annual average temperatures at the depths of 80 and 320 cm in new site were lower than those in old site.This paper provided certain correction stand for the use of observation data from new and old sites.展开更多
To study on the numerical simulation calculation reliability of sea-crossing bridge under complex wave forces,the paper applied GPS deformation monitoring and numerical simulation calculation by researching Qingdao Ji...To study on the numerical simulation calculation reliability of sea-crossing bridge under complex wave forces,the paper applied GPS deformation monitoring and numerical simulation calculation by researching Qingdao Jiaozhou Bay Sea-Crossing Bridge.The db3 wavelet three-layer decomposition was used on the horizontal movement of the sea-crossing bridge and the wind speed of the waves to analyze their correlation.The complex wave forces value of Qingdao Jiaozhou Bay Sea-Crossing Bridge was loaded on FLAC3D software successfully to make numerical simulation calculation of bridge deformation.Since the accuracy of the GPS deformation monitoring reaches millimeter level,it was used to monitor the exact value of the bridge deformation to judge the reliability of numerical simulation.The relative errors of displacement in X,Y and Z directions were between 33%and 41%through comparison.It could be seen that the numerical simulation error was relatively large,which was mainly due to various environmental factors and the deviation of applied wave forces.However,numerical simulation generally reflects the deformation law of the sea-crossing bridge under complex wave forces,providing an effectively technical support for the safe operation assessment of the sea-crossing bridge.展开更多
A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k-e turbulence model was applied to describe the flow, t...A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k-e turbulence model was applied to describe the flow, the discrete phase model （DPM） was applied to generate particle trajectories, and the governing equations are solved using the finite volume method. To validate this model, the numerical results were compared with data obtained from a full-scale physical model. The results show that： （1） the realizable k-e model applied for turbulence modeling describes well the flow pattern in octagonal tanks, giving an average relative error of velocities between simulated and measured values of 18% from contour maps of velocity magnitudes; （2） the DPM was applied to obtain particle trajectories and to simulate the rate of particle removal from the tank. The average relative error of the removal rates between simulated and measured values was 11%. The DPM can be used to assess the self-cleaning capability of an octagonal tank; （3） a comprehensive account of the hydrodynamics within an octagonal tank can be assessed from simulations. The velocity distribution was uniform with an average velocity of 15 cm/s; the velocity reached 0.8 m/s near the inlet pipe, which can result in energy losses and cause wall abrasion; the velocity in tank corners was more than 15 cm/s, which suggests good water mixing, and there was no particle sedimentation. The percentage of particle removal for octagonal tanks was 90% with the exception of a little accumulation of 〈5 mm particle in the area between the inlet pipe and the wall. This study demonstrated a consistent numerical model of the hydrodynamics within octagonal tanks that can be further used in their design and optimization as well as promote the wide use of computational fluid dynamics in aquaculture engineering.展开更多
文摘The orientation strategy of side pipe and the heat transfer performance of six ground heat exchangers(GHEs) were optimized by numerical simulation,with soil being treated as a porous medium.An experiment on the heat transfer of four GHEs was carried out in 2010.Results indicate that the velocity field is disturbed by GHEs.The optimal orientation strategy of side pipe is that the upward pipe is located upstream and the downward pipe downstream.The space between GHEs should be appropriately adjusted,depending on the direction and flow velocity.Groups of GHEs should be installed perpendicular to the mainstream in a single row,but if the acreage does not meet the requirements,GHEs should be installed in staggered multiple rows.Fewer GHEs parallel to the mainstream strengthen the heat transfer.Moreover,numerical results agree well with the test data,with the maximum relative error being less than 7.7%.
文摘This study aimed to conduct statistical analysis of temperature,relative humidity,wind direction,wind velocity,deep ground temperature and other related data from National Meteorological Observing Station of Hejian City in 2012.According to the results,observation data varied due to different instruments and equipments,surrounding environments and underlying surface properties.The difference value of monthly average temperature between new site and old site ranged from-0.5 to 0 ℃; the difference value of monthly average maximum temperature ranged from-0.4 to 0.2 ℃; the difference value of monthly average minimum temperature ranged from-0.8 to 0 ℃; the difference value of monthly extreme maximum temperature ranged from-1.1 to 0.6 ℃; the difference value of monthly extreme minimum temperature ranged from-1.2 to 0.3 ℃.Annual average temperature,annual average maximum temperature and annual average minimum temperature in new site were lower than those in old site; annual extreme maximum temperature in new site was higher than that in old site; annual extreme minimum temperature in new site was lower than that in old site.The difference value of monthly average relative humidity between new site and old site ranged from 2％ to 6％; the difference value of monthly minimum relative humidity ranged from-4％ to 5％.Annual minimum relative humidity in new site was consistent with that in old site.The difference value of 2 min average wind velocity between new site and old site ranged from-0.1 to 0.4 m/s; the difference value of monthly maximum wind velocity ranged from-1.2 to 2.2 m/s; the difference value of monthly extreme wind velocity ranged from-2.0 to 2.8 m/s.Annual maximum wind velocity in new site was basically consistent with that in old site; annual extreme wind velocity in new site was significantly higher than that in old site; annual wind direction frequency in new site was lower than that in old site; annual most frequent wind direction in new site was S and that in old site was SSW.The difference value of average temperature at the depth of 40 cm ranged from-1.1 to 2.5 ℃; the difference value of average temperature at the depth of 80 cm ranged from-2.4 to 2.1 ℃; the difference value of average temperature at the depth of 160 cm ranged from-2.5 to 2.7 ℃; the difference value of average temperature at the depth of 320 cm ranged from-1.6 to 1.1 ℃.Annual average temperatures at the depths of 40 and 160 cm in new site were higher than those in old site,while annual average temperatures at the depths of 80 and 320 cm in new site were lower than those in old site.This paper provided certain correction stand for the use of observation data from new and old sites.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2020MD024)。
文摘To study on the numerical simulation calculation reliability of sea-crossing bridge under complex wave forces,the paper applied GPS deformation monitoring and numerical simulation calculation by researching Qingdao Jiaozhou Bay Sea-Crossing Bridge.The db3 wavelet three-layer decomposition was used on the horizontal movement of the sea-crossing bridge and the wind speed of the waves to analyze their correlation.The complex wave forces value of Qingdao Jiaozhou Bay Sea-Crossing Bridge was loaded on FLAC3D software successfully to make numerical simulation calculation of bridge deformation.Since the accuracy of the GPS deformation monitoring reaches millimeter level,it was used to monitor the exact value of the bridge deformation to judge the reliability of numerical simulation.The relative errors of displacement in X,Y and Z directions were between 33%and 41%through comparison.It could be seen that the numerical simulation error was relatively large,which was mainly due to various environmental factors and the deviation of applied wave forces.However,numerical simulation generally reflects the deformation law of the sea-crossing bridge under complex wave forces,providing an effectively technical support for the safe operation assessment of the sea-crossing bridge.
基金Supported by the Application Research Project of Post-Doctoral Researchers in Qingdao(No.ZQ51201415037)the Modern Agriculture Industry System Construction of Special Funds(No.CARS-50-G10)+1 种基金the Special Project about Independent Innovation and Achievement Transformation of Shandong Province(No.2014ZZCX07102)the Key R&D Program of Jiangsu Province(No.BE2015328)
文摘A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k-e turbulence model was applied to describe the flow, the discrete phase model （DPM） was applied to generate particle trajectories, and the governing equations are solved using the finite volume method. To validate this model, the numerical results were compared with data obtained from a full-scale physical model. The results show that： （1） the realizable k-e model applied for turbulence modeling describes well the flow pattern in octagonal tanks, giving an average relative error of velocities between simulated and measured values of 18% from contour maps of velocity magnitudes; （2） the DPM was applied to obtain particle trajectories and to simulate the rate of particle removal from the tank. The average relative error of the removal rates between simulated and measured values was 11%. The DPM can be used to assess the self-cleaning capability of an octagonal tank; （3） a comprehensive account of the hydrodynamics within an octagonal tank can be assessed from simulations. The velocity distribution was uniform with an average velocity of 15 cm/s; the velocity reached 0.8 m/s near the inlet pipe, which can result in energy losses and cause wall abrasion; the velocity in tank corners was more than 15 cm/s, which suggests good water mixing, and there was no particle sedimentation. The percentage of particle removal for octagonal tanks was 90% with the exception of a little accumulation of 〈5 mm particle in the area between the inlet pipe and the wall. This study demonstrated a consistent numerical model of the hydrodynamics within octagonal tanks that can be further used in their design and optimization as well as promote the wide use of computational fluid dynamics in aquaculture engineering.
