Under coronal conditions, the steady state rate-equations are used to calculate the inter-stage line ratios between Li-like ls22p(2P3/2)→ls22s(2S1/2) and He-like ls2p(1P1)→1s2(1S0) transitions for Ti in the electron...Under coronal conditions, the steady state rate-equations are used to calculate the inter-stage line ratios between Li-like ls22p(2P3/2)→ls22s(2S1/2) and He-like ls2p(1P1)→1s2(1S0) transitions for Ti in the electronic temperature ranges from 0.1keV to 20 keV. The results show that the temperature sensitivities are higher at the electronic temperature less than 5000 eV and the temperature sensitivities will decrease with the increase of electronic temperature.展开更多
The electric submersible pump(ESP) is a crucial apparatus utilized for lifting in the oil extraction process.Its lifting capacity is enhanced by the multi-stage tandem structure, but variations in energy characteristi...The electric submersible pump(ESP) is a crucial apparatus utilized for lifting in the oil extraction process.Its lifting capacity is enhanced by the multi-stage tandem structure, but variations in energy characteristics and internal flow across stages are also introduced. In this study, the inter-stage variability of energy characteristics in ESP hydraulic systems is investigated through entropy production(EP) analysis,which incorporates numerical simulations and experimental validation. The EP theory facilitates the quantification of energy loss in each computational subdomain at all ESP stages, establishing a correlation between microscopic flow structure and energy dissipation within the system. Furthermore, the underlying causes of inter-stage variability in ESP hydraulic systems are examined, and the advantages and disadvantages of applying the EP theory in this context are evaluated. Consistent energy characteristics within the ESP, aligned with the distribution of internal flow structure, are provided by the EP theory, as demonstrated by our results. The EP theory also enables the quantitative analysis of internal flow losses and complements existing performance analysis methods to map the internal flow structure to hydraulic losses. Nonetheless, an inconsistency between the energy characterization based on EP theory and the traditional efficiency index when reflecting inter-stage differences is identified. This inconsistency arises from the exclusive focus of the EP theory on flow losses within the flow field, disregarding the quantification of external energy input to the flow field. This study provides a reference for the optimization of EP theory in rotating machinery while deeply investigating the energy dissipation characteristics of multistage hydraulic system, which has certain theoretical and practical significance.展开更多
For the compressor with shrouded stator blades,the stator well is a rotor-stator space between the rotating drum and the stationary shroud.Due to the pressure difference,a reverse leakage flow would travel through the...For the compressor with shrouded stator blades,the stator well is a rotor-stator space between the rotating drum and the stationary shroud.Due to the pressure difference,a reverse leakage flow would travel through the stator well and inject into the main flow path.Although,the labyrinth seal is commonly placed under the shroud,the rotation effect and seal clearance variation in actual operation process have great impact on the characteristics of this inter-stage leakage,as well as the compressor performance.In this paper,experiments were conducted at a compressor inter-stage seal test rig.The leakage flow rates,total temperatures and swirl ratios were obtained at different speeds and working clearances.The proportions of rotation effect and the clearance reduction effect were analyzed by data processing.Comparisons indicate that the working clearance and leakage flow reduce about 43%and 50%respectively,when the rotational speedω=8100 r/min.The proportion of reduction caused by the rotation effect is around 15%,while the influence of working clearance variation is much greater,accounting for about 35%.The windage heating coefficient and swirl ratio in the outlet cavity are almost in exponential relationship with the rotor speed.The increases in total temperature and swirl ratio generated by the rotation effect are found to be about 80%.In addition,the swirl and radial velocity profiles in the cavities were discussed by validated numerical simulations to reveal the typical flow characteristics.The data presented can provide guidance for better leakage conditions prediction as well as the inter-stage seal design enhancement.展开更多
针对光伏并网系统在最大功率点跟踪(maximum power point tracking,MPPT)控制下直流侧电压振荡引起的间谐波电流现象,结合光伏逆变器控制系统特点,建立了单级式光伏并网系统解析模型。分析了直流侧电压振荡到交流侧间谐波电流的传变规律...针对光伏并网系统在最大功率点跟踪(maximum power point tracking,MPPT)控制下直流侧电压振荡引起的间谐波电流现象,结合光伏逆变器控制系统特点,建立了单级式光伏并网系统解析模型。分析了直流侧电压振荡到交流侧间谐波电流的传变规律,并通过仿真实验验证了传变规律的准确性。分析了MPPT控制参数和逆变器控制参数对光伏并网系统输出间谐波电流的影响。仿真结果表明MPPT控制参数影响间谐波电流幅值和频率分布,逆变器控制参数在不同频段下对间谐波电流幅值影响不同。展开更多
文摘Under coronal conditions, the steady state rate-equations are used to calculate the inter-stage line ratios between Li-like ls22p(2P3/2)→ls22s(2S1/2) and He-like ls2p(1P1)→1s2(1S0) transitions for Ti in the electronic temperature ranges from 0.1keV to 20 keV. The results show that the temperature sensitivities are higher at the electronic temperature less than 5000 eV and the temperature sensitivities will decrease with the increase of electronic temperature.
基金financially supported by the China Postdoctoral Science Foundation(Grant No.2023M732979 and No.2022TQ0127)the Cooperative Research Project of the Ministry of Education's "Chunhui Program"(Grant No.HZKY20220117)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20220587)the National Natural Science Foundation of China(Grant No.52309112)。
文摘The electric submersible pump(ESP) is a crucial apparatus utilized for lifting in the oil extraction process.Its lifting capacity is enhanced by the multi-stage tandem structure, but variations in energy characteristics and internal flow across stages are also introduced. In this study, the inter-stage variability of energy characteristics in ESP hydraulic systems is investigated through entropy production(EP) analysis,which incorporates numerical simulations and experimental validation. The EP theory facilitates the quantification of energy loss in each computational subdomain at all ESP stages, establishing a correlation between microscopic flow structure and energy dissipation within the system. Furthermore, the underlying causes of inter-stage variability in ESP hydraulic systems are examined, and the advantages and disadvantages of applying the EP theory in this context are evaluated. Consistent energy characteristics within the ESP, aligned with the distribution of internal flow structure, are provided by the EP theory, as demonstrated by our results. The EP theory also enables the quantitative analysis of internal flow losses and complements existing performance analysis methods to map the internal flow structure to hydraulic losses. Nonetheless, an inconsistency between the energy characterization based on EP theory and the traditional efficiency index when reflecting inter-stage differences is identified. This inconsistency arises from the exclusive focus of the EP theory on flow losses within the flow field, disregarding the quantification of external energy input to the flow field. This study provides a reference for the optimization of EP theory in rotating machinery while deeply investigating the energy dissipation characteristics of multistage hydraulic system, which has certain theoretical and practical significance.
基金supported by the Fundamental Research Funds for the Central Universities(No.3132020121,No.3132020192)Natural Science Foundation of Liaoning Province(No.2020-BS-069),which are gratefully acknowledged。
文摘For the compressor with shrouded stator blades,the stator well is a rotor-stator space between the rotating drum and the stationary shroud.Due to the pressure difference,a reverse leakage flow would travel through the stator well and inject into the main flow path.Although,the labyrinth seal is commonly placed under the shroud,the rotation effect and seal clearance variation in actual operation process have great impact on the characteristics of this inter-stage leakage,as well as the compressor performance.In this paper,experiments were conducted at a compressor inter-stage seal test rig.The leakage flow rates,total temperatures and swirl ratios were obtained at different speeds and working clearances.The proportions of rotation effect and the clearance reduction effect were analyzed by data processing.Comparisons indicate that the working clearance and leakage flow reduce about 43%and 50%respectively,when the rotational speedω=8100 r/min.The proportion of reduction caused by the rotation effect is around 15%,while the influence of working clearance variation is much greater,accounting for about 35%.The windage heating coefficient and swirl ratio in the outlet cavity are almost in exponential relationship with the rotor speed.The increases in total temperature and swirl ratio generated by the rotation effect are found to be about 80%.In addition,the swirl and radial velocity profiles in the cavities were discussed by validated numerical simulations to reveal the typical flow characteristics.The data presented can provide guidance for better leakage conditions prediction as well as the inter-stage seal design enhancement.
文摘针对光伏并网系统在最大功率点跟踪(maximum power point tracking,MPPT)控制下直流侧电压振荡引起的间谐波电流现象,结合光伏逆变器控制系统特点,建立了单级式光伏并网系统解析模型。分析了直流侧电压振荡到交流侧间谐波电流的传变规律,并通过仿真实验验证了传变规律的准确性。分析了MPPT控制参数和逆变器控制参数对光伏并网系统输出间谐波电流的影响。仿真结果表明MPPT控制参数影响间谐波电流幅值和频率分布,逆变器控制参数在不同频段下对间谐波电流幅值影响不同。
