Based on theoretical analysis two modified log-wake laws for turbulent flow in smooth pipes are obtained, one is applicable to the outer region and other one to inner region, the new law for the outer region fits the ...Based on theoretical analysis two modified log-wake laws for turbulent flow in smooth pipes are obtained, one is applicable to the outer region and other one to inner region, the new law for the outer region fits the velocity profile measured in smooth pipes by Zagarola very well and the effect of Reynolds number can be taken into consideration, the velocity profile for inner region satisfies the wall boundary conditions ,equals zero at the pipe wall and smoothly joins up with the velocity profile in outer region, the adopted eddy viscosity model is consistent with Laufer＇s, Nunner＇s and Reichardt＇s experimental data.展开更多
have been done in the past by many researchers.Many factors which affect scour around piers such as shape of piers,size,positioning and orientation etc.have been studied in detail by them.However,similar studies in me...have been done in the past by many researchers.Many factors which affect scour around piers such as shape of piers,size,positioning and orientation etc.have been studied in detail by them.However,similar studies in meandering channels are scanty.Very few researchers have studied the effect of angular displacement which has considerable effects of scour around bridge piers.In this paper an attempt has been made to carry out a detailed study of angular displacement on scour.A constant diameter bridge pier of circular shape has been tested in a meandering channel bend with bend angle as 800.The test bed was prepared by using uniform sand having d50 as 0.27 mm and run was taken for a discharge of 2.5 l/s.展开更多
Spur dykes also known as Groynes are often used to either divert or attract the flow from the main structure to safeguard their life.Those structures may be bridge piers,abutments or any similar hydraulics structures....Spur dykes also known as Groynes are often used to either divert or attract the flow from the main structure to safeguard their life.Those structures may be bridge piers,abutments or any similar hydraulics structures.Spur dykes are also used to save the cutting of banks on concave side of stream.Lots of work have been done in recent past on spur dykes by many investigators in which various hydraulic and geometrical parameters of spur dykes such as discharge,sediment size,flow velocity,shear stress,spur dykes shape,size and submergence etc.are studied in detail.But mostly all the studies were pointed out in straight open channels.Very few studies were done in curved channel and only their similar effects were studied.In present thesis main emphasis is given to study the effect of orientation and location of spur dykes in meandering channel on the bed of downstream side.In the present study experimental work has been carried out in 80°bend and constant discharge(Q=4.5 l/s)is allowed to pass in channel without spur dyke.It is found that maximum scouring occurs at angular displacementθ=60°to 80°in the vicinity of outer bank.To minimize this scouring,spur dyke has been installed at angular displacementθ=20°,40°&60°by changing the dyke angleα=60°,90°&120°respectively.It is found that scouring atθ=60°is reduced by installing spur dyke at angular displacementθ=40°which is oriented atα=60°and scouring atθ=80°is reduced by installing spur dyke at angular displacementθ=60°which is oriented atα=60°.展开更多
应用数值模拟对浮法玻璃熔窑底烧式喷枪的燃气配送比例进行了模拟优化研究,从火焰温度、高温区覆盖面积和CO浓度等对不同进气配比下的燃气燃烧效果进行了对比分析。研究表明:燃气喷枪外管流量较大有助于喷射火焰对玻璃液面的加热,提高...应用数值模拟对浮法玻璃熔窑底烧式喷枪的燃气配送比例进行了模拟优化研究,从火焰温度、高温区覆盖面积和CO浓度等对不同进气配比下的燃气燃烧效果进行了对比分析。研究表明:燃气喷枪外管流量较大有助于喷射火焰对玻璃液面的加热,提高火焰温度和覆盖面积,但外管燃气流量过大将导致燃气燃烧不充分、火焰温度下降。在大管压力2.9 k Pa小管压力0.55 k Pa的进气压力配比下,火焰温度较高,火焰覆盖区域较大。展开更多
文摘Based on theoretical analysis two modified log-wake laws for turbulent flow in smooth pipes are obtained, one is applicable to the outer region and other one to inner region, the new law for the outer region fits the velocity profile measured in smooth pipes by Zagarola very well and the effect of Reynolds number can be taken into consideration, the velocity profile for inner region satisfies the wall boundary conditions ,equals zero at the pipe wall and smoothly joins up with the velocity profile in outer region, the adopted eddy viscosity model is consistent with Laufer＇s, Nunner＇s and Reichardt＇s experimental data.
文摘have been done in the past by many researchers.Many factors which affect scour around piers such as shape of piers,size,positioning and orientation etc.have been studied in detail by them.However,similar studies in meandering channels are scanty.Very few researchers have studied the effect of angular displacement which has considerable effects of scour around bridge piers.In this paper an attempt has been made to carry out a detailed study of angular displacement on scour.A constant diameter bridge pier of circular shape has been tested in a meandering channel bend with bend angle as 800.The test bed was prepared by using uniform sand having d50 as 0.27 mm and run was taken for a discharge of 2.5 l/s.
文摘Spur dykes also known as Groynes are often used to either divert or attract the flow from the main structure to safeguard their life.Those structures may be bridge piers,abutments or any similar hydraulics structures.Spur dykes are also used to save the cutting of banks on concave side of stream.Lots of work have been done in recent past on spur dykes by many investigators in which various hydraulic and geometrical parameters of spur dykes such as discharge,sediment size,flow velocity,shear stress,spur dykes shape,size and submergence etc.are studied in detail.But mostly all the studies were pointed out in straight open channels.Very few studies were done in curved channel and only their similar effects were studied.In present thesis main emphasis is given to study the effect of orientation and location of spur dykes in meandering channel on the bed of downstream side.In the present study experimental work has been carried out in 80°bend and constant discharge(Q=4.5 l/s)is allowed to pass in channel without spur dyke.It is found that maximum scouring occurs at angular displacementθ=60°to 80°in the vicinity of outer bank.To minimize this scouring,spur dyke has been installed at angular displacementθ=20°,40°&60°by changing the dyke angleα=60°,90°&120°respectively.It is found that scouring atθ=60°is reduced by installing spur dyke at angular displacementθ=40°which is oriented atα=60°and scouring atθ=80°is reduced by installing spur dyke at angular displacementθ=60°which is oriented atα=60°.
文摘应用数值模拟对浮法玻璃熔窑底烧式喷枪的燃气配送比例进行了模拟优化研究,从火焰温度、高温区覆盖面积和CO浓度等对不同进气配比下的燃气燃烧效果进行了对比分析。研究表明:燃气喷枪外管流量较大有助于喷射火焰对玻璃液面的加热,提高火焰温度和覆盖面积,但外管燃气流量过大将导致燃气燃烧不充分、火焰温度下降。在大管压力2.9 k Pa小管压力0.55 k Pa的进气压力配比下,火焰温度较高,火焰覆盖区域较大。
