A technique was developed to study mass trans fer process and inter facial reaction in two phases system. This constant inter facial cell with a laminar flow was made into a cubic structure. The two fluids were contin...A technique was developed to study mass trans fer process and inter facial reaction in two phases system. This constant inter facial cell with a laminar flow was made into a cubic structure. The two fluids were continuously recycled and mixed. The concentration of each liquid could be monitored by two different methods. This kind of structure made both flows near the inter face flow parallel to the inter face. The inter face was smooth and steady. The mass trans fer rate could be judged by the linear velocity of the flows. The technique can be used for the analyses of the control step in both phases near the inter face in a diffusion control process. A preliminary hydrodynamics and mass trans fer study on the cell was presented, which ensures the distinguishing between a diffusion and a chemical reaction control process. A simplified mass transfer equation,N =0.5303D 1 /2* (Ci- Cb)* (V / B) 1/2, was achieved.展开更多
The extraction kinetics of La(III) from aqueous chloride solutions into n-heptane solutions of bifunctional ionic liquid extractant [A336][CA-12](tricaprylmethylammonium sec-octylphenoxy acetic acid) was investigated ...The extraction kinetics of La(III) from aqueous chloride solutions into n-heptane solutions of bifunctional ionic liquid extractant [A336][CA-12](tricaprylmethylammonium sec-octylphenoxy acetic acid) was investigated using a constant interfacial cell with laminar flow. The effects of stirring speed, temperature and specific interfacial area on the extraction rate were examined. The results indicate that mass transfer kinetics of La(III) is a mixed-controlled process influenced by interfacial reaction. On the basis of mass transfer kinetic results in the extraction of La(III) by [A336][CA-12], the extraction rate equation of La(III) is proposed in terms of pseudo-firstorder constants, which is supported by the measured thermodynamic equations. The mass-transfer kinetic model deduced from the rate controlling step is adequate to interpret the experimental data qualitatively.展开更多
Heat transfer characteristics of oscillating turbulent air flow in a pipe heated with constant heat flux were experimentally investigated.The experiments were performed over a range of 245.7 to 902 of the kinetic Reyn...Heat transfer characteristics of oscillating turbulent air flow in a pipe heated with constant heat flux were experimentally investigated.The experiments were performed over a range of 245.7 to 902 of the kinetic Reynolds number and 25 to 175 of the dimensionless oscillation amplitude.The effects of these two dimensionless parameters were analyzed.The results show that the cycle-averaged local Nusselt number increases with both the kinetic Reynolds number and the dimensionless oscillation amplitude.The space-cycle averaged Nusselt number also effectively increases with the kinetic Reynolds number and the dimensionless oscillation amplitude.Based on the experimental data,a correlation equation of the space-cycle averaged Nusselt number for air in terms of these two dimensionless parameters has been obtained.展开更多
Swept wing is widely used in civil aircraft,whose airfoil is chosen,designed and optimized to increase the cruise speed and decrease the drag coefficient.The parameters of swept wing,such as sweep angle and angle of a...Swept wing is widely used in civil aircraft,whose airfoil is chosen,designed and optimized to increase the cruise speed and decrease the drag coefficient.The parameters of swept wing,such as sweep angle and angle of attack,are determined according to the cruise lift coefficient requirement,and the drag coefficient is expected to be predicted accurately,which involves the instability characteristics and transition position of the flow.The pressure coefficient of the RAE2822 wing with given constant lift coefficient is obtained by solving the three-dimensional Navier-Stokes equation numerically,and then the mean flow is calculated by solving the boundary layer（BL） equation with spectral method.The cross-flow instability characteristic of boundary layer of swept wing in the windward and leeward is analyzed by linear stability theory（LST）,and the transition position is predicted by eNmethod.The drag coefficient is numerically predicted by introducing a laminar/turbulent indicator.A simple approach to calculate the lift coefficient of swept wing is proposed.It is found that there is a quantitative relationship between the angle of attack and sweep angle when the lift coefficient keeps constant;when the angle of attack is small,the flow on the leeward of the wing is stable.when the angle of attack is larger than 3°,the flow becomes unstable quickly;with the increase of sweep angle or angle of attack the disturbance on the windward becomes more unstable,leading to the moving forward of the transition position to the leading edge of the wing;the drag coefficient has two significant jumping growth due to the successive occurrence of transition in the windward and the leeward;the optimal range of sweep angle for civil aircraft is suggested.展开更多
This study presents the effect of the magnetic field with constant intensity on the pulsatile flow through a rigid tube. Basing on the experimental results, the influence of the magnetic field on the blood viscosity i...This study presents the effect of the magnetic field with constant intensity on the pulsatile flow through a rigid tube. Basing on the experimental results, the influence of the magnetic field on the blood viscosity is considered The analytic solution of the pulsatile flow through a rigid tube under constant magnetic field intensitier and the effect of the magnetic field on the velocity distribution, flow and impedance in a rigid tube are given. this investigation is valuable for understanding the influence of the magnetic field on the blood circulation.展开更多
Pressure transient analysis has been used to evaluate performance of a well located between one sealing fault and one constant pressure boundary. Type curves were generated by determining 1) dimensionless pressure and...Pressure transient analysis has been used to evaluate performance of a well located between one sealing fault and one constant pressure boundary. Type curves were generated by determining 1) dimensionless pressure and 2) rate of change of dimensionless pressure drop with respect to dimensionless time. When the well is located closer to the no flow boundary, both sets of type curves have three distinct slopes. These slopes characterize: 1) flow in an infinite reservoir, 2) presence of the no flow, and 3) the constant-pressure boundaries. When the well is closer to the constant pressure boundary, the type curves show two distinct slopes. These correspond to: 1) flow in an infinite reservoir, and 2) the presence of a constant pressure boundary. The type curves can be used to match actual pressure drawdown data and determine the drainage area and relative well location with respect to physical boundaries.展开更多
A numerical model was proposed to simulate the capillary micro-flow through a fiber bundle. The capillary pressure was predicted by the Young-Laplace equation and the corresponding optimal values of permeability were ...A numerical model was proposed to simulate the capillary micro-flow through a fiber bundle. The capillary pressure was predicted by the Young-Laplace equation and the corresponding optimal values of permeability were found by a trial-and-error method. The empirical Kozeny constants which are dependent on fiber volume fraction were recormnended for the prediction of permeability.展开更多
Fully developed turbulence measurements in pipe flow were made in the Reynolds number ranging from 10 x 10~3 to 350 x 10~3 with a hot-wire anemometer and a Pitot tube.Comparisons were made with the experimental result...Fully developed turbulence measurements in pipe flow were made in the Reynolds number ranging from 10 x 10~3 to 350 x 10~3 with a hot-wire anemometer and a Pitot tube.Comparisons were made with the experimental results of previous work.The mean velocity profile and the turbulent intensity in the experiments in- dicate that for the mean velocity profile,in the fully developed turbulent pipe flow, von Kármán's constant κ is a function of Reynolds number,i.e.κ increases slowly with the Reynolds number.The empirical relationships could not be considered to be accurate enough to describe the fully developed turbulence over the whole Reynolds number range in pipe flow.展开更多
An adaptive response compensation technique has been proposed to compensate for the response lag of the constant-current hot-wire anemometer (CCA) by taking advantage of digital signal processing technology. First, we...An adaptive response compensation technique has been proposed to compensate for the response lag of the constant-current hot-wire anemometer (CCA) by taking advantage of digital signal processing technology. First, we have developed a simple response compensation scheme based on a precise theoretical expression for the frequency response of the CCA (Kaifuku et al. 2010, 2011), and verified its effectiveness experimentally for hot-wires of 5 μm, 10 μm and 20 μm in diameter. Then, another novel technique based on a two-sensor probe technique—originally developed for the response compensation of fine-wire thermocouples (Tagawa and Ohta 1997;Tagawa et al. 1998)—has been proposed for estimating thermal time-constants of hot-wires to realize the in-situ response compensation of the CCA. To demonstrate the usefulness of the CCA, we have applied the response compensation schemes to multipoint velocity measure- ment of a turbulent wake flow formed behind a circular cylinder by using a CCA probe consisting of 16 hot-wires, which were driven simultaneously by a very simple constant-current circuit. As a result, the proposed response compensation techniques for the CCA work quite successfully and are capable of improving the response speed of the CCA to obtain reliable measurements comparable to those by the commercially-available constant-temperature hot-wire anemometer (CTA).展开更多
The nature of gravitation and <em>G</em> is not well understood. A new gravitation mechanism is proposed that explains the origin and essence of the gravitational constant, <em>G</em>. Based on...The nature of gravitation and <em>G</em> is not well understood. A new gravitation mechanism is proposed that explains the origin and essence of the gravitational constant, <em>G</em>. Based on general relativity, the vacuum is considered to be a superfluid with measurable density. Rotating bodies drag vacuum and create a vortex with gradient pressure. The drag force of vacuum fluid flow in the arm of the vortex is calculated relative to the static vacuum and a value that is numerically equal to that of <em>G</em> is obtained. Using Archimedes’ principle, it is determined that <em>G</em> is the volume of vacuum displaced by a force equivalent to its weight which is equal to the drag force of the vacuum. It is concluded that the gravitational constant <em>G</em> expresses the force needed to displace a cubic metre of vacuum that weighs one kg in one second. Therefore, <em>G</em> is not a fundamental physical constant but rather is an expression of the resistance encountered by the gravitational force in the vacuum.展开更多
The Singular Integral Operators Method (S.I.O.M.) is applied to the determination of the free-surface profile of an un-steady flow over a spillway, which defines a classical hydraulics problem in open channel flow. Th...The Singular Integral Operators Method (S.I.O.M.) is applied to the determination of the free-surface profile of an un-steady flow over a spillway, which defines a classical hydraulics problem in open channel flow. Thus, with a known flow rate Q, then the velocities and the elevations are computed on the free surface of the spillway flow. For the numerical evaluation of the singular integral equations both constant and linear elements are used. An application is finally given to the determination of the free-surface profile of a special spillway and comparing the numerical results with corresponding results by the Boundary Integral Equation Method (B.I.E.M.) and by using experiments.展开更多
Analytical solutions of temperature distributions and the Nusselt numbers in forced convection are reported for flow through infinitely long parallel plates, where the upper plate moves in the flow direction with cons...Analytical solutions of temperature distributions and the Nusselt numbers in forced convection are reported for flow through infinitely long parallel plates, where the upper plate moves in the flow direction with constant velocity and the lower plate is kept stationary. The flow is assumed to be laminar, both hydro-dynamically and thermally fully developed, taking into account the effect of viscous dissipation of the flowing fluid. Both the plates being kept at specified and at different constant heat fluxes are considered as thermal boundary conditions. The solutions obtained from energy equation are in terms of Brinkman number, dimensionless velocity and heat flux ratio. These parameters greatly influence and give complete understanding on heat transfer rates that has potentials for designing and analyzing energy equipment and processes.展开更多
深部岩石裂隙在剪切过程中形貌不断发生改变,导致裂隙渗流特性极其复杂,进而影响深部岩体工程的稳定性。为探明恒定法向刚度(constant normal stiffness,简称CNS)边界条件下岩石裂隙的剪切渗流特性,基于分形理论构建了不同粗糙度三维自...深部岩石裂隙在剪切过程中形貌不断发生改变,导致裂隙渗流特性极其复杂,进而影响深部岩体工程的稳定性。为探明恒定法向刚度(constant normal stiffness,简称CNS)边界条件下岩石裂隙的剪切渗流特性,基于分形理论构建了不同粗糙度三维自仿射裂隙面,采用考虑裂隙粗糙度退化的剪切数值方法分析了不同CNS边界条件下裂隙岩石剪切过程中几何形貌参数的演变规律。随后利用COMSOL软件对受剪后的裂隙进行渗流计算,研究了法向刚度、剪切位移和分形维数对裂隙非线性渗流特性的影响。结果表明:(1)裂隙的力学开度随着分形维数的增大而增大,但法向刚度的增加会减缓其增长速度;接触率主要受法向刚度控制,并随其增大而增大。(2)裂隙渗流的压力梯度与流量关系能够用Forchheimer定律准确描述,拟合系数A和B随剪切位移的增大呈幂函数减小趋势,随法向刚度的增加而增加,随裂隙分形维数的增加而减小。(3)裂隙的水力开度随分形维数的增加而增加,随法向刚度的增加而减小,并建立了以力学开度和开度标准差为自变量的水力开度模型。(4)裂隙渗流的临界雷诺数随剪切位移的增加先减小后增大,并随分形维数和法向刚度的增加而减小,以裂隙的分形维数、接触率和水力开度模型为基础,建立了CNS条件下剪切裂隙的临界雷诺数计算拟合公式。展开更多
文摘A technique was developed to study mass trans fer process and inter facial reaction in two phases system. This constant inter facial cell with a laminar flow was made into a cubic structure. The two fluids were continuously recycled and mixed. The concentration of each liquid could be monitored by two different methods. This kind of structure made both flows near the inter face flow parallel to the inter face. The inter face was smooth and steady. The mass trans fer rate could be judged by the linear velocity of the flows. The technique can be used for the analyses of the control step in both phases near the inter face in a diffusion control process. A preliminary hydrodynamics and mass trans fer study on the cell was presented, which ensures the distinguishing between a diffusion and a chemical reaction control process. A simplified mass transfer equation,N =0.5303D 1 /2* (Ci- Cb)* (V / B) 1/2, was achieved.
基金Supported by the National Natural Science Foundation of China(51174184)National Basic Research Program of China(2012CBA01202)+3 种基金the Key Research Programof the Chinese Academy of Sciences(KGZD-EW-201-1)the Science and Technology Planof Nantong City(BK2013030)the University Science Research Project of Jiangsu Province(14KJB150019)Open Subject of Changchun Institute of Applied Chemistry,Chinese Academy of Sciences(RERU2014016)
文摘The extraction kinetics of La(III) from aqueous chloride solutions into n-heptane solutions of bifunctional ionic liquid extractant [A336][CA-12](tricaprylmethylammonium sec-octylphenoxy acetic acid) was investigated using a constant interfacial cell with laminar flow. The effects of stirring speed, temperature and specific interfacial area on the extraction rate were examined. The results indicate that mass transfer kinetics of La(III) is a mixed-controlled process influenced by interfacial reaction. On the basis of mass transfer kinetic results in the extraction of La(III) by [A336][CA-12], the extraction rate equation of La(III) is proposed in terms of pseudo-firstorder constants, which is supported by the measured thermodynamic equations. The mass-transfer kinetic model deduced from the rate controlling step is adequate to interpret the experimental data qualitatively.
文摘Heat transfer characteristics of oscillating turbulent air flow in a pipe heated with constant heat flux were experimentally investigated.The experiments were performed over a range of 245.7 to 902 of the kinetic Reynolds number and 25 to 175 of the dimensionless oscillation amplitude.The effects of these two dimensionless parameters were analyzed.The results show that the cycle-averaged local Nusselt number increases with both the kinetic Reynolds number and the dimensionless oscillation amplitude.The space-cycle averaged Nusselt number also effectively increases with the kinetic Reynolds number and the dimensionless oscillation amplitude.Based on the experimental data,a correlation equation of the space-cycle averaged Nusselt number for air in terms of these two dimensionless parameters has been obtained.
基金co-supported by the National Natural Science Foundation of China(Nos.11332007,11672351)the Tianjin Natural Science Foundation of China(No.15JCYBJC19500)+1 种基金the Hebei Natural Science Foundation of China(No.A2015105073)an open fund from the State Key Laboratory of Aerodynamics of China(No.SKLA201601)
文摘Swept wing is widely used in civil aircraft,whose airfoil is chosen,designed and optimized to increase the cruise speed and decrease the drag coefficient.The parameters of swept wing,such as sweep angle and angle of attack,are determined according to the cruise lift coefficient requirement,and the drag coefficient is expected to be predicted accurately,which involves the instability characteristics and transition position of the flow.The pressure coefficient of the RAE2822 wing with given constant lift coefficient is obtained by solving the three-dimensional Navier-Stokes equation numerically,and then the mean flow is calculated by solving the boundary layer（BL） equation with spectral method.The cross-flow instability characteristic of boundary layer of swept wing in the windward and leeward is analyzed by linear stability theory（LST）,and the transition position is predicted by eNmethod.The drag coefficient is numerically predicted by introducing a laminar/turbulent indicator.A simple approach to calculate the lift coefficient of swept wing is proposed.It is found that there is a quantitative relationship between the angle of attack and sweep angle when the lift coefficient keeps constant;when the angle of attack is small,the flow on the leeward of the wing is stable.when the angle of attack is larger than 3°,the flow becomes unstable quickly;with the increase of sweep angle or angle of attack the disturbance on the windward becomes more unstable,leading to the moving forward of the transition position to the leading edge of the wing;the drag coefficient has two significant jumping growth due to the successive occurrence of transition in the windward and the leeward;the optimal range of sweep angle for civil aircraft is suggested.
基金Project supported by the National Natural Science Foundation of China
文摘This study presents the effect of the magnetic field with constant intensity on the pulsatile flow through a rigid tube. Basing on the experimental results, the influence of the magnetic field on the blood viscosity is considered The analytic solution of the pulsatile flow through a rigid tube under constant magnetic field intensitier and the effect of the magnetic field on the velocity distribution, flow and impedance in a rigid tube are given. this investigation is valuable for understanding the influence of the magnetic field on the blood circulation.
文摘Pressure transient analysis has been used to evaluate performance of a well located between one sealing fault and one constant pressure boundary. Type curves were generated by determining 1) dimensionless pressure and 2) rate of change of dimensionless pressure drop with respect to dimensionless time. When the well is located closer to the no flow boundary, both sets of type curves have three distinct slopes. These slopes characterize: 1) flow in an infinite reservoir, 2) presence of the no flow, and 3) the constant-pressure boundaries. When the well is closer to the constant pressure boundary, the type curves show two distinct slopes. These correspond to: 1) flow in an infinite reservoir, and 2) the presence of a constant pressure boundary. The type curves can be used to match actual pressure drawdown data and determine the drainage area and relative well location with respect to physical boundaries.
文摘A numerical model was proposed to simulate the capillary micro-flow through a fiber bundle. The capillary pressure was predicted by the Young-Laplace equation and the corresponding optimal values of permeability were found by a trial-and-error method. The empirical Kozeny constants which are dependent on fiber volume fraction were recormnended for the prediction of permeability.
基金The project supported by the Deutscher Akademische Austauschdienst (DAAD)
文摘Fully developed turbulence measurements in pipe flow were made in the Reynolds number ranging from 10 x 10~3 to 350 x 10~3 with a hot-wire anemometer and a Pitot tube.Comparisons were made with the experimental results of previous work.The mean velocity profile and the turbulent intensity in the experiments in- dicate that for the mean velocity profile,in the fully developed turbulent pipe flow, von Kármán's constant κ is a function of Reynolds number,i.e.κ increases slowly with the Reynolds number.The empirical relationships could not be considered to be accurate enough to describe the fully developed turbulence over the whole Reynolds number range in pipe flow.
文摘An adaptive response compensation technique has been proposed to compensate for the response lag of the constant-current hot-wire anemometer (CCA) by taking advantage of digital signal processing technology. First, we have developed a simple response compensation scheme based on a precise theoretical expression for the frequency response of the CCA (Kaifuku et al. 2010, 2011), and verified its effectiveness experimentally for hot-wires of 5 μm, 10 μm and 20 μm in diameter. Then, another novel technique based on a two-sensor probe technique—originally developed for the response compensation of fine-wire thermocouples (Tagawa and Ohta 1997;Tagawa et al. 1998)—has been proposed for estimating thermal time-constants of hot-wires to realize the in-situ response compensation of the CCA. To demonstrate the usefulness of the CCA, we have applied the response compensation schemes to multipoint velocity measure- ment of a turbulent wake flow formed behind a circular cylinder by using a CCA probe consisting of 16 hot-wires, which were driven simultaneously by a very simple constant-current circuit. As a result, the proposed response compensation techniques for the CCA work quite successfully and are capable of improving the response speed of the CCA to obtain reliable measurements comparable to those by the commercially-available constant-temperature hot-wire anemometer (CTA).
文摘The nature of gravitation and <em>G</em> is not well understood. A new gravitation mechanism is proposed that explains the origin and essence of the gravitational constant, <em>G</em>. Based on general relativity, the vacuum is considered to be a superfluid with measurable density. Rotating bodies drag vacuum and create a vortex with gradient pressure. The drag force of vacuum fluid flow in the arm of the vortex is calculated relative to the static vacuum and a value that is numerically equal to that of <em>G</em> is obtained. Using Archimedes’ principle, it is determined that <em>G</em> is the volume of vacuum displaced by a force equivalent to its weight which is equal to the drag force of the vacuum. It is concluded that the gravitational constant <em>G</em> expresses the force needed to displace a cubic metre of vacuum that weighs one kg in one second. Therefore, <em>G</em> is not a fundamental physical constant but rather is an expression of the resistance encountered by the gravitational force in the vacuum.
文摘The Singular Integral Operators Method (S.I.O.M.) is applied to the determination of the free-surface profile of an un-steady flow over a spillway, which defines a classical hydraulics problem in open channel flow. Thus, with a known flow rate Q, then the velocities and the elevations are computed on the free surface of the spillway flow. For the numerical evaluation of the singular integral equations both constant and linear elements are used. An application is finally given to the determination of the free-surface profile of a special spillway and comparing the numerical results with corresponding results by the Boundary Integral Equation Method (B.I.E.M.) and by using experiments.
文摘Analytical solutions of temperature distributions and the Nusselt numbers in forced convection are reported for flow through infinitely long parallel plates, where the upper plate moves in the flow direction with constant velocity and the lower plate is kept stationary. The flow is assumed to be laminar, both hydro-dynamically and thermally fully developed, taking into account the effect of viscous dissipation of the flowing fluid. Both the plates being kept at specified and at different constant heat fluxes are considered as thermal boundary conditions. The solutions obtained from energy equation are in terms of Brinkman number, dimensionless velocity and heat flux ratio. These parameters greatly influence and give complete understanding on heat transfer rates that has potentials for designing and analyzing energy equipment and processes.
文摘深部岩石裂隙在剪切过程中形貌不断发生改变,导致裂隙渗流特性极其复杂,进而影响深部岩体工程的稳定性。为探明恒定法向刚度(constant normal stiffness,简称CNS)边界条件下岩石裂隙的剪切渗流特性,基于分形理论构建了不同粗糙度三维自仿射裂隙面,采用考虑裂隙粗糙度退化的剪切数值方法分析了不同CNS边界条件下裂隙岩石剪切过程中几何形貌参数的演变规律。随后利用COMSOL软件对受剪后的裂隙进行渗流计算,研究了法向刚度、剪切位移和分形维数对裂隙非线性渗流特性的影响。结果表明:(1)裂隙的力学开度随着分形维数的增大而增大,但法向刚度的增加会减缓其增长速度;接触率主要受法向刚度控制,并随其增大而增大。(2)裂隙渗流的压力梯度与流量关系能够用Forchheimer定律准确描述,拟合系数A和B随剪切位移的增大呈幂函数减小趋势,随法向刚度的增加而增加,随裂隙分形维数的增加而减小。(3)裂隙的水力开度随分形维数的增加而增加,随法向刚度的增加而减小,并建立了以力学开度和开度标准差为自变量的水力开度模型。(4)裂隙渗流的临界雷诺数随剪切位移的增加先减小后增大,并随分形维数和法向刚度的增加而减小,以裂隙的分形维数、接触率和水力开度模型为基础,建立了CNS条件下剪切裂隙的临界雷诺数计算拟合公式。
