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Procedure for determining the number of thermal diffusion columns in square cascade for separation of Ne stable isotopes

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Nuclear Science and Techniques 2023年第5期34卷 47-55页

作者： Fatemeh Mansourzadeh Mohammad Mahdi Shadman Javad Karimi Sabet Valiyollah Ghazanfari Nuclear Fuel Cycle Research School Nuclear Science and Technology Research InstituteTehranIran

The thermal diffusion column represents one method of separating stable isotopes.This method is advantageous for smallscale operations because of the simplicity of the apparatus and small inventory,especially in gas-phase operations.Consequently,it has attracted attention for its applicability in tritium and noble gas separation systems.In this study,the R cascade was used to design and determine the number of columns.A square cascade was adopted for the final design because of its flexibility,and calculations were performed to separate 20Ne and 22Ne isotopes.All the R cascades that enriched the Ne isotopes by more than 99%were investigated,the number of columns was determined,and the square cascade parameters were optimized using the specified columns.Additionally,a calculation code“RSQ_cascade”was developed.A unit separation factor of three was considered,and the number of studied stages ranged from 10 to 20.The results showed that the column separation power,relative total flow rate,and required number of columns were linearly related to the number of stages.The separation power and relative total flow decreased and the number of columns increased as the stage number increased.Therefore,a cascade of 85 columns is recommended to separate the stable Ne isotopes.These calculations yielded a 17-stage square cascade with five columns in each stage.By changing the stage cut,feed point,and cascade feed flow rate,the best parameters for the square cascade were determined according to the cascade and column separation powers.As the column separation power had a maximum value in cascade feed 50,it was selected for separating Ne isotopes.

关键词： Stable isotope Thermal diffusion cascade Separation Neon

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Investigation of flow unsteadiness in a highly-loaded compressor cascade using a dynamic mode decomposition method

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Chinese Journal of Aeronautics 2022年第5期35卷 275-290页

作者： Guangyao AN Yanhui WU Jinhua LANG Zhiyang CHEN Xiaobing ZHOU School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China Shaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine Xi’an 710129China

Unsteady flow in the hub endwall region has long been a hot topic in the turbomachinery community.However important it is to the performance of the whole engine,the coherent unsteady flow phenomena are still not well understood.In this paper,the complex flow field in the hub endwall of a cantilevered compressor cascade has been investigated through numerical approach.The predicted results were validated by experimental data.To highlight the dominant flow structures among irregular and chaotic motions of various vortices,a Dynamic Mode Decomposition(DMD)method was utilized.The results show that there exist three dominant periodic flow structures:the oscillation of the leakage vortex,a circumferential migration of a Breakdown Induced Vortex(BIV)and the fluctuation of the passage vortex.These three coherent structures all together form a self-sustained closed loop which accounts for the flow unsteadiness of the studied cascade.During this process,the BIV plays a key role in inducing the flow unsteadiness.Only if the BIV is strong enough to affect the passage vortex,the flow unsteadiness occurs.This study expands current knowledge base of flow unsteadiness in a compressor environment,and shows the efficacy of the DMD method for revealing the origin of flow unsteadiness.

关键词： cascade Compressor Dynamic Mode Decomposition(DMD) Endwall Unsteady flow Vortex breakdown

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Topological analysis of plasma flow control on corner separation in a highly loaded compressor cascade

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Acta Mechanica Sinica 2012年第5期28卷 1277-1286页

作者： Xiao-Hu Zhao Yun Wu Ying-Hong Li Xue-De Wang Qin Zhao Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University

In this paper, flow behavior and topology structure in a highly loaded compressor cascade with and without plasma aerodynamic actuation （PAA） are investigated. Streamline pattern, total pressure loss coefficient, outlet flow angle and topological analysis are considered to study the effect and mechanism of the plasma flow control on corner separation. Results presented include the boundary layer flow behavior, effects of three types of PAA on separated flows and performance parameters, topology structures and sequences of singular points with and without PAA. Two separation lines, reversed flow and backflow exist on the suction surface. The cross flow on the endwall is an important element for the comer separation. PAA can reduce the undertuming and overturning as well as the total pressure loss, leading to an overall increase of flow turning and enhancement of aerodynamic performance. PAA can change the topology structure, sequences of singular points and their corresponding separation lines. Types II and III PAA are much more efficient in controlling comer separation and enhancing aerodynamic performances than type I.

关键词： Plasma aerodynamic actuation - Compressor cascade Topology structure Corner separation

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Effects of Plasma Aerodynamic Actuation on Corner Separation in a Highly Loaded Compressor cascade

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Plasma Science and Technology 2014年第3期16卷 244-250页

作者：王学德赵小虎李应红吴云赵勤 Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University

This paper reports experimental results on the effects of plasma aerodynamic actua- tion （PAA） on corner separation control in a highly loaded, low speed, linear compressor cascade. Total pressure loss coefficient distribution was adopted to evaluate the corner separation control effect in wind tunnel experiments. Results of pressure measurements and particle image velocime- try （PIV） show that the control effect of pitch-wise PAA on the endwall is much better than that of stream-wise PAA on the suction surface. When both the pitch-wise PAA on the endwall and stream-wise PAA on the suction surface are turned on simultaneously, the control effect is the best among all three PAA types. The mechanisms of nanosecond discharge and microsecond discharge PAA are different in corner separation control. The control effect of microsecond discharge PAA turns out better with the increase of discharge voltage and duty cycle. Compared with microsec- ond discharge PAA, nanosecond discharge PAA is more effective in preventing corner separation when the freestream velocity increases. Frequency is one of the most important parameters in plasma flow control. The optimum excitation frequency of microsecond discharge PAA is 500 Hz, which is different from the frequency corresponding to the case with a Strouhal number of unity.

关键词： plasma aerodynamic actuation corner separation compressor cascade

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An efficient synthesis of isocoumarins via a CuI catalyzed cascade reaction process

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Science China Chemistry 2009年第10期52卷 1616-1621页

作者： WANG LeiLei ZHANG XiaoJing JIANG YongWen MA DaWei Shenyang Pharmaceutical University Shenyang 110016China State Key Laboratory of Bioorganic Chemistry and Natural Products Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

3-Alkyl isocoumarins are provided by CuI/amino acid-catalyzed Sonogashira coupling reaction of o-bromo benzoic acids and terminal alkynes and the subsequent additive cyclization. This cascade process allows synthesis ... 详细信息

关键词： coupling cascade reaction copper iodide isocoumarins

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Frequency Analyses for Mechanism Research of Unsteady Flow Inside Three Dimensional Compressor cascade

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Journal of Thermal Science 2004年第3期13卷 207-212页

作者： Sheng Zhou Hongbin Wu Xinqian Zheng Beijing Univ Aeronaut & Astronaut Natl Key Lab Aircraft Engine Beijing 100083 Peoples R China

Numerical simulations are carried out for unsteady flow field of certain kind of 3D compressor cascade. Emphasis is laid on vortex shedding and frequency analysis in a compressor cascade. Numerical simulations using unsteady Reynolds-averaged viscous turbulent equations are carried out. The results show that the flows in separated areas and wake areas are characterized as periodic or quasi-periodic vortex shedding and the frequencies of vortex shedding vary with incidences and Mach number. At the same Mach number, the frequency of vortex shedding will decrease as the incidence increases. Yet, the frequency will increase as the Mach number increases at the same incidence. In the same computation case, the frequency of vortex shedding will vary along the span of blade. The frequency is smaller at the middle of the span than that at the hub.

关键词： axial flow compressor cascade unsteady flow separated flow frequency of vortex shedding.

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Enantioselective Construction of Functionalized Thiochromans via Squaramide-Catalyzed Asymmetric cascade Sulfa-Michael/Michael Addition

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Chinese Journal of Chemistry 2014年第9期32卷 853-858页

作者： Yi Yang Daming Du School of Chemical Engineering and Environment Beijing Institute of TechnologyBeijing 100081China

An efficient enantioselective cascade sulfa-Michael/Michael addition reaction of trans-3-(2-mercaptophenyl)-2-propenoic acid ethyl ester with nitroalkenes catalyzed by a chiral squaramide catalyst was disclosed.This cascade reaction afforded thiochroman derivatives with three contiguous stereocenters in high yields(up to 94%),excellent diastereoselectivities(up to>25∶1 dr)and enantioselectivities(up to 99% ee).

关键词： organocatalysis squaramide Michael addition thiochromans cascade

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Numerical Investigation of Flow Separation Control on a Highly Loaded Compressor cascade by Plasma Aerodynamic Actuation

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Chinese Journal of Aeronautics 2012年第3期25卷 349-360页

作者： ZHAO Xiaohu LI Yinghong WU Yun ZHU Tao LI Yiwen Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi'an 710038China

To discover the characteristic of separated flows and mechanism of plasma flow control on a highly loaded compressor cascade, numerical investigation is conducted. The simulation method is validated by oil flow visualization and pressure distribution. The loss coefficients, streamline patterns, and topology structure as well as vortex structure are analyzed. Results show that the numbers of singular points increase and three pairs of additional singular points of topology structure on solid surface generate with the increase of angle of attack, and the total pressure loss increases greatly. There are several principal vortices inside the cascade passage. The pressure side leg of horse-shoe vortex coexists within a specific region together with passage vortex, but finally merges into the latter. Corner vortex exists independently and does not evolve from the suction side leg of horse-shoe vortex. One pair of radial coupling-vortex exists near blade trailing edge and becomes the main part of backflow on the suction surface. Passage vortex interacts with the concentrated shedding vortex and they evolve into a large-scale vortex rotating in the direction opposite to passage vortex. The singular points and separation lines represent the basic separation feature of cascade passage. Plasma actuation has better effect at low freestream velocity, and the relative reductions of pitch-averaged total pressure loss coefficient with different actuation layouts of five and two pairs of electrodes are up to 30.8% and 26.7% while the angle of attack is 2~. Plasma actuation changes the local topology structure, but does not change the number relation of singular points. One pair of additional singular point of topology structure generates with plasma actuation and one more reattachment line appears, both of which break the separation line on the suction surface.

关键词： plasma aerodynamic actuation cascade oil flow visualization topology structure vortex singular point

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Performance Assessment of Air-Cooled Steam Condenser with Guide Vane cascade

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Journal of Thermal Science 2019年第5期28卷 993-1003页

作者： ZHANG Xuelei LI Yunpeng CHEN Haiping School of Energy Power and Mechanical Engineering North China Electric Power University

Ambient wind has an unfavourable impact on air-cooled steam condenser(ACSC) performance. A new measure to improve ACSC performance is proposed by setting a diffusion type guide vane cascade beneath the ACSC platform. The numerical models are developed to illustrate the effects of diffusion type guide vane cascade on ACSC performance. The simulation results show that this vane cascade can cause the increases in coolant flows across almost all fans due to its diffusion function and lower flow resistance. Meanwhile, the guide vane cascade also decreases the fan inlet temperatures because of the uniform flow field around the condenser cells. Comparing with the case without guide device, the overall heat transfer efficiency is increased by 11.2% for guide vane cascade case under the condition of 9 m/s. The heat transfer efficiency firstly enhances and then decreases with decreasing stagger angle of guide vane under a certain wind speed. The optimum stagger angle corresponding to the maximum heat transfer efficiency is about 65.5°. The heat transfer efficiency always enhances as increasing vane cascade height, and a vane cascade with 20 m to 30 m height may be suitable to the ACSC as considering the cost.

关键词： air-cooled steam condenser ambient wind guide vane cascade heat transfer

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Effects of End-Bend and Curved Blades on the Flow Field and Loss of a Compressor Linear cascade in the Design Condition

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Journal of Thermal Science 2019年第4期28卷 801-810页

作者： KAN Xiaoxu WU Wanyang YANG Ling ZHONG Jingjun Merchant Marine College Shanghai Maritime University

Curved blade and end-bend blade are considered as effective passive control methods for improving the aerodynamic performance of a compressor cascade,and their applicability also needs to be further studied.A highly-loaded compressor linear cascade in the design condition was taken as the research objective in this paper.Numerical simulation was used to study the positive and negative effects of these methods on the flow loss of the cascade by redistributing the vortex structures.Results show that:the curved blade could reduce the flow loss to 2.55%,while the end-bend blade and the end-bend+curved blade increase it to 10.58%and 2.19%,respectively.The positive effect of the curved blade weakens the strength and scale of Concentrated Shedding Vortex(CSV),which accounts for 59.2%of the total flow loss.The negative effect of the end-bend blade exacerbates the low-energy fluid clusters from the end wall and wake into CSV.Finally,the end-bend+curved blade can take their own strengths,but it enhances the twisting motion of Passage Vortex(PV)and CSV,which makes it fail to reduce the flow loss.Therefore,the positive and negative effects of these methods on the flow loss of a compressor cascade are much clearer.In addition,we also predict the potential danger of the end-bend blade in the negative incidence conditions and provides some suggestion for future study.

关键词： compressor linear cascade flow loss vortex structure curved blade end-bend blade design condition

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