Numerical investigations are conducted to explore the aerodynamic characteristics of three-dimensional Co-Flow Jet(CFJ) wing with simple high-lift devices during low-speed takeoff and landing. Effects of three crucial...Numerical investigations are conducted to explore the aerodynamic characteristics of three-dimensional Co-Flow Jet(CFJ) wing with simple high-lift devices during low-speed takeoff and landing. Effects of three crucial parameters of CFJ wing, i.e., angle of attack, jet momentum and swept angle, are comprehensively examined. Additionally, the aerodynamic characteristics of two CFJ configurations, i.e., using open and discrete slots for injection, are compared. The results show that applying CFJ technique to a wing with simple high-lift device is able to generate more lift,reduce drag and enlarge stall margin with lower energy expenditure due to the super-circulation effect. Increasing the jet intensity can reduce the drag significantly, which is mainly contributed by the reaction jet force. The Oswald efficiency factor is, in some circumstances, larger than one,which indicates the potential of CFJ in reducing induced drag. Compared with clean wing configuration, using CFJ technique allows the aerodynamic force variation less sensitive to the swept angle, and such phenomenon is better observed for small swept angle region. Eventually, it is interesting to know that the discrete slotted CFJ configuration demonstrates a promising enhancement in aerodynamic performance in terms of high lift, low drag and efficiency.展开更多
The purpose of this experimental study is to evaluate the feasibility and oil recovery efficiency of continuous N_(2) injection in a multi-well fractured-cavity reservoir.In this study,the similar criterion of physica...The purpose of this experimental study is to evaluate the feasibility and oil recovery efficiency of continuous N_(2) injection in a multi-well fractured-cavity reservoir.In this study,the similar criterion of physical simulation was firstly discussed.In order to reveal the mechanism of remaining oil startup and production performance characteristic by continuous N_(2) injection,a visualized twodimensional fractured-cavity model and a three-dimensional pressure resistant model were designed and fabricated respectively based on the similar theory.And the 2D visualized physical experiments and 3D physical experiments were performed with the simulated oil and brine reservoir samples in Tahe oilfield.Four groups of experiments in 2D and 3D model were performed,each of which included bottom water depletion driving,water injection and N_(2) injection.The 2D visualized experiments indicated the main mechanism of N_(2) developing remaining oil was to occupy the high position and replace the attic oil due to gravitational differentiation.Furthermore,both the 2D and 3D experiments demonstrated that higher oil recovery factor could be achieved if N_(2) was injected through high positional wells.The 3D physical model is closer to the real reservoir condition,so the production performance can reflect the real field production process.This paper confirmed the efficiency of continuous N2 flooding in the light oil saturated fractured-cavity reservoir.展开更多
Background:In clinical laboratories,reagent depletion can significantly compromise the accuracy of K^(+),Na^(+),and Cl^(-)measurements,posing risks to patient safety.Patient-based real-time quality control(PBRTQC)has ...Background:In clinical laboratories,reagent depletion can significantly compromise the accuracy of K^(+),Na^(+),and Cl^(-)measurements,posing risks to patient safety.Patient-based real-time quality control(PBRTQC)has emerged as a valuable tool for early detection of analytical errors.However,the effectiveness of PBRTQC may be influenced using data processing methods.Among these,truncation,tail-retention,and tail-shrinkage are three commonly used data truncation techniques.Despite their potential,the clinical early-warning performance of PBRTQC with these methods under reagent depletion conditions remains unclear.Therefore,this study aims to evaluate the clinical early-warning efficacy of PBRTQC when integrated with these three data truncation methods(truncation,tail-retention,and tail-shrinkage)for K^(+),Na^(+),and Cl^(-)measurements during reagent depletion scenarios.Methods:A controlled experimental design was used with routine patient test results as the control group and simulated reagent depletion scenarios as experimental groups.PBRTQC was applied to integrated datasets processed by the three trun-cation methods.Alarm timeliness rates for detecting abnormal results were evaluated for K^(+),Na^(+),and Cl^(-).Results:Under internal standard solution depletion,the number of samples required for error detection(NPed)for K^(+)using the truncation,tail-retention,and tail-shrinkage methods was 38,10,and 10,respectively.For Na^(+),the NPed was 55,5,and 10,respectively,while for Cl^(-),it was 0,11 and 16,respectively.During diluent depletion,K^(+)and Na^(+)showed 0 with the truncation method but 10 for both the tail-retention and tail-shrinkage methods;Cl^(-)showed 0 with the truncation method but 11 with the tail-retention method and 16 with the tail-shrinkage method.With reference solution depletion,the NPed for K^(+)using the truncation,tail-retention,tail-shrinkage methods was 42,35,and 39,respectively;the NPed for Na^(+)was 135,25,and 25,respectively;and the NPed for Cl^(-)was 140,31,and 36,respectively.Conclusion:During a shortage of reagents,the effectiveness of early warning of the PBRTQC program was the highest with the tail-retention method,followed by the tail-shrinkage method.The truncation method showed the lowest effectiveness with the risk of missed error detection.Considering data variability,the tail-shrinkage method is recommended as the optimal data processing method.展开更多
The application of Carbon Dioxide(CO_(2))injection in enhanced oil recovery(EOR)has evolved,making a major benefit for increasing the production level from mature reservoirs.This paper investigates the optimization of...The application of Carbon Dioxide(CO_(2))injection in enhanced oil recovery(EOR)has evolved,making a major benefit for increasing the production level from mature reservoirs.This paper investigates the optimization of the CO_(2)-EOR process based on using a new mode of simulation-based sensitivity analysis to understand two main proposed strategies,namely continuous gas injection and water-alternating-gas(WAG)injection.Prominent dynamical features including multiphase flow and displacement mechanisms were effectively captured in the form of a detailed reservoir model developed with considerable care for both techniques.The performance of each injection method was determined from a comprehensive analysis on the major production performance metrics:i)Oil recovery factor,ii)Gas-oil ratio iii)Cumulative oil production.Applying a wide range of sensitivity methods that included proxy model,Morris analysis and Sobol method were used to analyze the main parameters affecting the effectiveness of CO_(2) injection.The analysis then produced an optimization framework highlighting conditions conducive to achieving maximum oil recovery.The results of the study point to the effectiveness of WAG injection strategy in promoting oil recovery through better mobility control and lower gas breakthrough risk compared with continuous gas injection.This approach enhances sweep efficiency and highlights the significance of selecting appropriate injection strategies to maximize recovery in immiscible CO_(2) flooding processes.The alternating phases of water and CO_(2) in the Water-Alternating-Gas(WAG)process are crucial for optimizing oil recovery outcomes.展开更多
基金the National Natural Science Foundation of China (No. 11672133)the Fundamental Research Funds for the Central Universities, China (No. kfjj20180104)support from Rotor Aerodynamics Key Laboratory, China (No. RAL20190202-2/RAL20190101-1)
文摘Numerical investigations are conducted to explore the aerodynamic characteristics of three-dimensional Co-Flow Jet(CFJ) wing with simple high-lift devices during low-speed takeoff and landing. Effects of three crucial parameters of CFJ wing, i.e., angle of attack, jet momentum and swept angle, are comprehensively examined. Additionally, the aerodynamic characteristics of two CFJ configurations, i.e., using open and discrete slots for injection, are compared. The results show that applying CFJ technique to a wing with simple high-lift device is able to generate more lift,reduce drag and enlarge stall margin with lower energy expenditure due to the super-circulation effect. Increasing the jet intensity can reduce the drag significantly, which is mainly contributed by the reaction jet force. The Oswald efficiency factor is, in some circumstances, larger than one,which indicates the potential of CFJ in reducing induced drag. Compared with clean wing configuration, using CFJ technique allows the aerodynamic force variation less sensitive to the swept angle, and such phenomenon is better observed for small swept angle region. Eventually, it is interesting to know that the discrete slotted CFJ configuration demonstrates a promising enhancement in aerodynamic performance in terms of high lift, low drag and efficiency.
基金The authors wish to thank the National Natural Science Foundation of China(NO.51174216)State Key Science&Technology Project of China(NO.2011ZX05009-004 and NO.2011ZX05052)for their financial support to carry out this research.The insightful and constructive comments of the anonymous reviewers are also gratefully acknowledged.
文摘The purpose of this experimental study is to evaluate the feasibility and oil recovery efficiency of continuous N_(2) injection in a multi-well fractured-cavity reservoir.In this study,the similar criterion of physical simulation was firstly discussed.In order to reveal the mechanism of remaining oil startup and production performance characteristic by continuous N_(2) injection,a visualized twodimensional fractured-cavity model and a three-dimensional pressure resistant model were designed and fabricated respectively based on the similar theory.And the 2D visualized physical experiments and 3D physical experiments were performed with the simulated oil and brine reservoir samples in Tahe oilfield.Four groups of experiments in 2D and 3D model were performed,each of which included bottom water depletion driving,water injection and N_(2) injection.The 2D visualized experiments indicated the main mechanism of N_(2) developing remaining oil was to occupy the high position and replace the attic oil due to gravitational differentiation.Furthermore,both the 2D and 3D experiments demonstrated that higher oil recovery factor could be achieved if N_(2) was injected through high positional wells.The 3D physical model is closer to the real reservoir condition,so the production performance can reflect the real field production process.This paper confirmed the efficiency of continuous N2 flooding in the light oil saturated fractured-cavity reservoir.
文摘Background:In clinical laboratories,reagent depletion can significantly compromise the accuracy of K^(+),Na^(+),and Cl^(-)measurements,posing risks to patient safety.Patient-based real-time quality control(PBRTQC)has emerged as a valuable tool for early detection of analytical errors.However,the effectiveness of PBRTQC may be influenced using data processing methods.Among these,truncation,tail-retention,and tail-shrinkage are three commonly used data truncation techniques.Despite their potential,the clinical early-warning performance of PBRTQC with these methods under reagent depletion conditions remains unclear.Therefore,this study aims to evaluate the clinical early-warning efficacy of PBRTQC when integrated with these three data truncation methods(truncation,tail-retention,and tail-shrinkage)for K^(+),Na^(+),and Cl^(-)measurements during reagent depletion scenarios.Methods:A controlled experimental design was used with routine patient test results as the control group and simulated reagent depletion scenarios as experimental groups.PBRTQC was applied to integrated datasets processed by the three trun-cation methods.Alarm timeliness rates for detecting abnormal results were evaluated for K^(+),Na^(+),and Cl^(-).Results:Under internal standard solution depletion,the number of samples required for error detection(NPed)for K^(+)using the truncation,tail-retention,and tail-shrinkage methods was 38,10,and 10,respectively.For Na^(+),the NPed was 55,5,and 10,respectively,while for Cl^(-),it was 0,11 and 16,respectively.During diluent depletion,K^(+)and Na^(+)showed 0 with the truncation method but 10 for both the tail-retention and tail-shrinkage methods;Cl^(-)showed 0 with the truncation method but 11 with the tail-retention method and 16 with the tail-shrinkage method.With reference solution depletion,the NPed for K^(+)using the truncation,tail-retention,tail-shrinkage methods was 42,35,and 39,respectively;the NPed for Na^(+)was 135,25,and 25,respectively;and the NPed for Cl^(-)was 140,31,and 36,respectively.Conclusion:During a shortage of reagents,the effectiveness of early warning of the PBRTQC program was the highest with the tail-retention method,followed by the tail-shrinkage method.The truncation method showed the lowest effectiveness with the risk of missed error detection.Considering data variability,the tail-shrinkage method is recommended as the optimal data processing method.
文摘The application of Carbon Dioxide(CO_(2))injection in enhanced oil recovery(EOR)has evolved,making a major benefit for increasing the production level from mature reservoirs.This paper investigates the optimization of the CO_(2)-EOR process based on using a new mode of simulation-based sensitivity analysis to understand two main proposed strategies,namely continuous gas injection and water-alternating-gas(WAG)injection.Prominent dynamical features including multiphase flow and displacement mechanisms were effectively captured in the form of a detailed reservoir model developed with considerable care for both techniques.The performance of each injection method was determined from a comprehensive analysis on the major production performance metrics:i)Oil recovery factor,ii)Gas-oil ratio iii)Cumulative oil production.Applying a wide range of sensitivity methods that included proxy model,Morris analysis and Sobol method were used to analyze the main parameters affecting the effectiveness of CO_(2) injection.The analysis then produced an optimization framework highlighting conditions conducive to achieving maximum oil recovery.The results of the study point to the effectiveness of WAG injection strategy in promoting oil recovery through better mobility control and lower gas breakthrough risk compared with continuous gas injection.This approach enhances sweep efficiency and highlights the significance of selecting appropriate injection strategies to maximize recovery in immiscible CO_(2) flooding processes.The alternating phases of water and CO_(2) in the Water-Alternating-Gas(WAG)process are crucial for optimizing oil recovery outcomes.
