The most prominent aspect of multiphase flow is the variation in the physical distribution of the phases in the flow conduit known as the flow pattern. Several different flow patterns can exist under different flow co...The most prominent aspect of multiphase flow is the variation in the physical distribution of the phases in the flow conduit known as the flow pattern. Several different flow patterns can exist under different flow conditions which have significant effects on liquid holdup, pressure gradient and heat transfer. Gas-liquid two-phase flow in an annulus can be found in a variety of practical situations. In high rate oil and gas production, it may be beneficial to flow fluids vertically through the annulus configuration between well tubing and casing. The flow patterns in annuli are different from pipe flow. There are both casing and tubing liquid films in slug flow and annular flow in the annulus. Multiphase heat transfer depends on the hydrodynamic behavior of the flow. There are very limited research results that can be found in the open literature for multiphase heat transfer in wellbore annuli. A mechanistic model of multiphase heat transfer is developed for different flow patterns of upward gas-liquid flow in vertical annuli. The required local flow parameters are predicted by use of the hydraulic model of steady-state multiphase flow in wellbore annuli recently developed by Yin et al. The modified heat-transfer model for single gas or liquid flow is verified by comparison with Manabe＇s experimental results. For different flow patterns, it is compared with modified unified Zhang et al. model based on representative diameters.展开更多
Based on the droplet-diffusion model by Kirillov and Smogalev (1969, 1972), a new analytical model of dryout point prediction in the steam-water flow for bilaterally and uniformly heated narrow annular gap was devel- ...Based on the droplet-diffusion model by Kirillov and Smogalev (1969, 1972), a new analytical model of dryout point prediction in the steam-water flow for bilaterally and uniformly heated narrow annular gap was devel- oped. Comparisons of the present model predictions with experimental results indicated that a good agreement in ac- curacy for the experimental parametric range (pressure from 0.8 to 3.5 MPa, mass flux of 60.39 to 135.6 kg?m-2?s-1 and heat flux of 5 to 50 kW?m-2). Prediction of dryout point was experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap heated by AC power supply.展开更多
In this paper, we discuss the uniqueness problem of algebroid functions on annull, we get several uniqueness theorems of algebroid functions on annuli, which extend the Nevanlinna value distribution theory for algebro...In this paper, we discuss the uniqueness problem of algebroid functions on annull, we get several uniqueness theorems of algebroid functions on annuli, which extend the Nevanlinna value distribution theory for algebroid functions on annuli.展开更多
Based on the governing equations of the inner cyinder of the unsteady flow of the power law fluid in eccentric annuli with the inner cylinder reciprocating axially in bipolar coordinate system, the calculation formula...Based on the governing equations of the inner cyinder of the unsteady flow of the power law fluid in eccentric annuli with the inner cylinder reciprocating axially in bipolar coordinate system, the calculation formulae of tangential force were established, and the relevant numerical calculation method was given. Taking the aqueous solution of partially hydrolyzed polyacrylamides (HPAM) for examples, the tangential forces were calculated by using the formulae and numerical calculation method mentioned above;the curves of the tangential force on the wall of the inner cylinder of HPAM aqueous solution were plotted;and the effects on the tangential force of the flow behavior index of the power law fluid, the stroke and the stroke frequency of the inner cylinder were analyzed.展开更多
The purpose of this paper is to find the effect of heat source/sink parameter on free convective flow of a polar fluid in open-ended vertical concentric annuli. Exact solutions of the non-dimensional differential equa...The purpose of this paper is to find the effect of heat source/sink parameter on free convective flow of a polar fluid in open-ended vertical concentric annuli. Exact solutions of the non-dimensional differential equations describing the flow model have been obtained one by one for two different cases of source and sink. To observe the effect of the physical parameters such as source/sink and vertex viscosity, the numerical results of the velocity and microrotational velocity are finally shown on the graphs.展开更多
Age of African pike Hepsetus odoe from Ado Ekiti Reservoir Ekiti State, Nigeria was studied. Annuli on the opercula bones and scales were used to determine the age. The standard length of specimens examined varied bet...Age of African pike Hepsetus odoe from Ado Ekiti Reservoir Ekiti State, Nigeria was studied. Annuli on the opercula bones and scales were used to determine the age. The standard length of specimens examined varied between 12.50 and 29.80 cm and body weight 10-385 g. Annuli （growth rings） observed on the opercula bones of specimens with mean standard lengths 21.70 ± 1.4 cm had one real annulus, 24.80 ± 1.1 cm had two real annuli, 27.4 ± 0.9 cm had three real annuli indicating age one, two, and three （1 ＋, 2＋, 3＋ ） respectively. Growth rings observed on scales appeared as interruptions in the normal pattems of scales. Specimens with mean standard lengths of 21.3 ± 1.5 cm, 24.7 ± 0.8 cm and 27.35 ± 11 cm were interpreted to be ages 1＋, 2＋, and 3＋ respectively. The maximum age of samples, derived from annuli on both opercula bones and scales was 3 years. Specimens below 18 cm standard length did not register any growth mark. The mean lengths at the estimated ages obtained using both opercula bones and scales were not significantly different （P 〉 0.05, P 〉 0.01）.展开更多
A narrow annular test section of 1.5mm gap and 1800mm length was designed and manufactured, with good tightness and insulation. Experiments were carried out to investigate characteristics of flow instability of forced...A narrow annular test section of 1.5mm gap and 1800mm length was designed and manufactured, with good tightness and insulation. Experiments were carried out to investigate characteristics of flow instability of forced-convection in vertical narrow annuli. Using distilled water as work fluid, the experiments were conducted at pressures of 1.0~3.0MPa, mass flow rates of 3.0~25kg/h, heating power of 3.0~ 6.5kW and inlet fluid temperature of 20 oC, 40 oC or 60oC. It was found that flow instability occured with fixed inlet condition and heating power when mass flow rate was below a special value. Effects of inlet subcooling, system pressure and mass flow rate on the system behavior were studied and the instability region was given.展开更多
基金sponsored by the National Natural Science Foundation of China (Grant No. 51504279)Shandong Provincial Natural Science Foundation, China (ZR2014EEQ021)+2 种基金Qingdao Science and Technology (15-9-1-96-jch)the Fundamental Research Funds for the Central Universities (17CX02073, 17CX02011A and R1502039A)973 Project (2015CB251206)
文摘The most prominent aspect of multiphase flow is the variation in the physical distribution of the phases in the flow conduit known as the flow pattern. Several different flow patterns can exist under different flow conditions which have significant effects on liquid holdup, pressure gradient and heat transfer. Gas-liquid two-phase flow in an annulus can be found in a variety of practical situations. In high rate oil and gas production, it may be beneficial to flow fluids vertically through the annulus configuration between well tubing and casing. The flow patterns in annuli are different from pipe flow. There are both casing and tubing liquid films in slug flow and annular flow in the annulus. Multiphase heat transfer depends on the hydrodynamic behavior of the flow. There are very limited research results that can be found in the open literature for multiphase heat transfer in wellbore annuli. A mechanistic model of multiphase heat transfer is developed for different flow patterns of upward gas-liquid flow in vertical annuli. The required local flow parameters are predicted by use of the hydraulic model of steady-state multiphase flow in wellbore annuli recently developed by Yin et al. The modified heat-transfer model for single gas or liquid flow is verified by comparison with Manabe＇s experimental results. For different flow patterns, it is compared with modified unified Zhang et al. model based on representative diameters.
文摘Based on the droplet-diffusion model by Kirillov and Smogalev (1969, 1972), a new analytical model of dryout point prediction in the steam-water flow for bilaterally and uniformly heated narrow annular gap was devel- oped. Comparisons of the present model predictions with experimental results indicated that a good agreement in ac- curacy for the experimental parametric range (pressure from 0.8 to 3.5 MPa, mass flux of 60.39 to 135.6 kg?m-2?s-1 and heat flux of 5 to 50 kW?m-2). Prediction of dryout point was experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap heated by AC power supply.
基金Project Supported by the Natural Science Foundation of China(11171013)
文摘In this paper, we discuss the uniqueness problem of algebroid functions on annull, we get several uniqueness theorems of algebroid functions on annuli, which extend the Nevanlinna value distribution theory for algebroid functions on annuli.
文摘Based on the governing equations of the inner cyinder of the unsteady flow of the power law fluid in eccentric annuli with the inner cylinder reciprocating axially in bipolar coordinate system, the calculation formulae of tangential force were established, and the relevant numerical calculation method was given. Taking the aqueous solution of partially hydrolyzed polyacrylamides (HPAM) for examples, the tangential forces were calculated by using the formulae and numerical calculation method mentioned above;the curves of the tangential force on the wall of the inner cylinder of HPAM aqueous solution were plotted;and the effects on the tangential force of the flow behavior index of the power law fluid, the stroke and the stroke frequency of the inner cylinder were analyzed.
文摘The purpose of this paper is to find the effect of heat source/sink parameter on free convective flow of a polar fluid in open-ended vertical concentric annuli. Exact solutions of the non-dimensional differential equations describing the flow model have been obtained one by one for two different cases of source and sink. To observe the effect of the physical parameters such as source/sink and vertex viscosity, the numerical results of the velocity and microrotational velocity are finally shown on the graphs.
文摘Age of African pike Hepsetus odoe from Ado Ekiti Reservoir Ekiti State, Nigeria was studied. Annuli on the opercula bones and scales were used to determine the age. The standard length of specimens examined varied between 12.50 and 29.80 cm and body weight 10-385 g. Annuli （growth rings） observed on the opercula bones of specimens with mean standard lengths 21.70 ± 1.4 cm had one real annulus, 24.80 ± 1.1 cm had two real annuli, 27.4 ± 0.9 cm had three real annuli indicating age one, two, and three （1 ＋, 2＋, 3＋ ） respectively. Growth rings observed on scales appeared as interruptions in the normal pattems of scales. Specimens with mean standard lengths of 21.3 ± 1.5 cm, 24.7 ± 0.8 cm and 27.35 ± 11 cm were interpreted to be ages 1＋, 2＋, and 3＋ respectively. The maximum age of samples, derived from annuli on both opercula bones and scales was 3 years. Specimens below 18 cm standard length did not register any growth mark. The mean lengths at the estimated ages obtained using both opercula bones and scales were not significantly different （P 〉 0.05, P 〉 0.01）.
文摘A narrow annular test section of 1.5mm gap and 1800mm length was designed and manufactured, with good tightness and insulation. Experiments were carried out to investigate characteristics of flow instability of forced-convection in vertical narrow annuli. Using distilled water as work fluid, the experiments were conducted at pressures of 1.0~3.0MPa, mass flow rates of 3.0~25kg/h, heating power of 3.0~ 6.5kW and inlet fluid temperature of 20 oC, 40 oC or 60oC. It was found that flow instability occured with fixed inlet condition and heating power when mass flow rate was below a special value. Effects of inlet subcooling, system pressure and mass flow rate on the system behavior were studied and the instability region was given.
