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Short circuit analysis of a fault-tolerant current-limiting high temperature superconducting transformer in a power system in presence of distributed generations

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Superconductivity 2024年第1期9卷 74-86页

作者： Alireza Sadeghi Shahin Alipour Bonab Wenjuan Song Mohammad Yazdani-Asrami propulsion Electrification&Superconductivity GroupAutonomous Systems&Connectivity DivisionJames Watt School of EngineeringUniversity of GlasgowGlasgow G128QQUnited Kingdom

Power transformers are key elements for the safe and reliable delivery of electrical energy generated by renewable energy resources to consumers via transmission ***‐tolerant current‐limiting High Temperature Superconducting(FTCL HTS)transformers are type of superconducting transformers that tolerate fault for seconds and limit the fault current without the threat of burnout or delamination of tapes and deformation of *** this paper,the fault performance of a FTCL HTS transformer in a standard IEEE power system is *** studied transformer is a 50 MVA 132 kV/13.8 kV transformer where both windings are made up of HTS *** understudied power system consists of two microgrids with distributed *** of the power in microgrids is supplied by the upstream grid which is connected to the microgrids through the HTS *** fault scenarios have been considered in this power system,in each one of these scenarios,a fault happens in one of the *** considered fault scenarios have an approximate fault current of 18x to 23x of the rated current in the secondary *** showed that insulated windings in FTCL HTS transformers could substantially reduce the peak temperature of the HTS windings,compared to bare ***,post‐fault loading is imposed on the HTS windings,to observe their performance against the current increase after fault *** this case,for the first scenario of the faults,the FTCL HTS transformer could tolerate 192%of post‐fault overloading,while this number for the second fault scenario is 170%.Finally,the impact of post‐fault loading on the full recovery time was discussed.

关键词： Fault Energy Heat dissipation Heat transfer Insulation Recovery Time Temperature rise

Bioinspired Hemostatic Strategy via Pulse Ejections for Severe Bleeding Wounds

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Research 2024年第1期2023卷 281-299页

作者： Bitao Lu Enling Hu Weiwei Ding Wenyi Wang Ruiqi Xie Kun Yu Fei Lu Guangqian Lan Fangyin Dai State Key Laboratory of Silkworm Genome Biology College of SericultureTextile and Biomass SciencesSouthwest UniversityChongqing 400715China Chongqing Engineering Research Center of Biomaterial Fiber and Modern Textile Chongqing 400715China division of Trauma and Surgical Intensive Care Unit Research Institute of General SurgeryJinling HospitalMedical School of Nanjing UniversityNanjing210002 Jiangsu ProvinceChina Department of Applied Biology and Chemical Technology The Hong Kong Polytechnic UniversityHong KongChina

Efficient hemostasis during emergency trauma with massive bleeding remains a critical challenge in prehospital ***,multiple hemostatic strategies are critical for treating large bleeding *** this study,inspired by bombardier beetles to eject toxic spray for defense,a shape-memory aerogel with an aligned microchannel structure was proposed,employing thrombin-carrying microparticles loaded as a built-in engine to generate pulse ejections for enhanced drug *** aerogels,after contact with blood,can rapidly expand inside the wound,offering robust physical barrier blocking,sealing the bleeding wound,and generating a spontaneous local chemical reaction causing an explosivelike generation of CO_(2) microbubbles,which provide propulsion thrust to accelerate burst ejection from arrays of microchannels for deeper and faster drug *** ejection behavior,drug release kinetics,and permeation capacity were evaluated using a theoretical model and experimentally *** novel aerogel showed remarkable hemostatic performance in severely bleeding wounds in a swine model and demonstrated good degradability and biocompatibility,displaying great potential for clinical application in humans.

关键词： wound sealing offering

Effects of axial gap and nozzle distribution on aerodynamic forces of a supersonic partial-admission turbine

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Chinese Journal of Aeronautics 2017年第6期30卷 1844-1853页

作者： Jinpeng JIANG Jiawen LI Guobiao CAI Jue WANG Qiyan LIN School of Astronautics Beihang University Beijing 100083 China System Engineering division China Academy of Launch Vehicle Technology Beijing 100076 China Beijing Aerospace propulsion Institute Beijing 100076 China

The turbine in an LH2/LOX rocket engine is designed as a two-stage supersonic partialadmission turbine. Three-dimensional steady and unsteady simulations were conducted to analyze turbine performance and aerodynamic forces on rotor blades. Different configurations were employed to investigate the effects of the axial gap and nozzle distribution on the predicted performance and aerodynamic forces. Rotor blades experience unsteady aerodynamic forces because of the partial admission. Aerodynamic forces show periodicity in the admission region, and are close to zero after leaving the admission region. The unsteady forces in frequency domain indicate that components exist in a wide frequency region, and the admission passing frequency is *** multiples of the rotational frequency which are multiples of the nozzle number in a fulladmission turbine are notable components. Results show that the turbine efficiency decreases as the axial gap between nozzles and the 1 st stage rotor（rotor 1） increases. Fluctuation of the circumferential aerodynamic force on rotor 1 blades decreases with the axial gap increasing. The turbine efficiency decreases as the circumferential spacing between nozzles increases. Fluctuations of the circumferential and axial aerodynamic forces increase as the circumferential spacing increases. As for the non-equidistant nozzle distribution, it produces similar turbine performance and amplitudefrequency characteristics of forces to those of the normal configuration, when the mean spacing is equal to that of the normal case.

关键词： Aerodynamic force Axial gap Computational fluid dynam-ics (CFD) Nozzle distribution Partial admission Turbine

Design of a two spool contra-rotating turbine for a turbo-fan engine

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propulsion and Power Research 2020年第3期9卷 225-239页

作者： Prathapanayaka Rajeevalochanam S.N.Agnimitra Sunkara Seepana Venkata Ramana Murthy R.Senthil Kumaran propulsion division CSIR-National Aerospace LaboratoriesBangaloreKarnataka560017India Turbine Group Gas Turbine Research EstablishmentDRDOBangalore.Karnataka560093India

Contra-rotating turbines offer enhanced performance over their conventional corotating *** addition,vaneless contra-rotating turbine stages offer lesser stage length along with improved ***-rotating turbines with a vaned LP stages offer a controlled work-split between the stages over a wider range of operating conditions by maintaining inlet swirl to the second *** objective of the present work is to design an equivalent vaned contra-rotating turbine for an existing co-rotating configuration of a two-spool turbo fan *** contra-rotating turbine is designed by retaining the existing flow path and HP turbine,and redesigning the LP turbine for fixed radial distributions of inlet total temperature,pressure and swirl.A comparative study between performance of the co-rotating and contra-rotating turbines is carried out for different *** testing of the LP stator and rotor mean sections was carried out to validate the *** LP stage of contra-rotating turbine exhibits a performance improvement by 2%points at design point,as per flow *** reduced flow deflection in stator row is the primary reason for significant reduction in profile and secondary losses in contra-rotating turbine,which contributed to the performance improvement.A significant reduction of 23%in blade weight and 45% in LP stator vane count is obtained.

关键词： Contra-rotating turbine Computational fluid dynamics Vaned contra-rotating Two spool Unsteady CFD

Mode coupling in converging Richtmyer-Meshkov instability of dual-mode interface

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Acta Mechanica Sinica 2020年第2期36卷 356-366页

作者： Zhangbo Zhou Juchun Ding Zhigang Zhai Wan Cheng Xisheng Luo Advanced propulsion Laboratory Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230026China Mechanical Engineering Physical Science and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal 23955-6900Saudi Arabia

The converging Richtmyer-Meshkov(RM)instability on single-and dual-mode N2/SF6 interfaces is studied by an upwind conservation element and solution element *** unperturbed case is first considered,and it is found that the shocked interface undergoes a long-term deceleration after a period of uniform *** evolution of single-mode interface at the early stage exhibits an evident nonlinearity,which can be reasonably predicted by the nonlinear model of Wang et al.(Phys Plasmas 22:082702,2015).During the deceleration stage,the perturbation amplitude drops quickly and even becomes a negative(phase inversion)before the reshock due to the Rayleigh-Taylor(RT)*** the reshock,the interface experiences a phase inversion again or does not,depending on the reshock *** growth of the second-order harmonic in the deceleration stage clearly reveals the competition between the RT effect and the *** dual-mode interfaces,the growth of the first mode(wavenumber k1)relies heavily on the second mode(wavenumber k2)due to the mode coupling ***,for cases where k2 is an even or odd multiple of k1,the growth of the first mode is inhibited or promoted depending on its initial amplitude sign and the phase difference between two basic waves,while for cases where k2 is a non-integer multiple of k1,the second mode has negligible influence on the first *** a systematic study,signs of perturbation amplitudes of the generated k2−k1 and k2+k1 waves are obtained for all possible dual-mode configurations,which are reasonably predicted by a modified Haan model(Phys Fluids B 3:2349-2355,1991).

关键词： Converging Richtmyer-Meshkov instability Dual-mode interface Mode coupling

Measurement of sub-fm/Hz^(1/2) displacement spectral densities in ultrahigh-Q single-crystal microcavities with hertz-level lasers

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Photonics Research 2022年第5期10卷 1202-1209页

作者： YOON-SOO JANG JINKANG LIM WENTING WANG SEUNG-WOO KIM ANATOLIY SAVCHENKOV ANDREY BMATSKO CHEE WEI WONG Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory University of CaliforniaLos AngelesCalifornia 90095USA division of Physical Metrology Korea Research Institute of Standards and Science(KRISS)Daejeon 34113Republic of Korea CACI-LGS Labs Florham ParkNew Jersey 07932USA Department of Mechanical Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea OEwaves Inc. PasadenaCalifornia 91107USA Jet propulsion Laboratory California Institute of TechnologyPasadenaCalifornia 91109USA

Tracing a resonance frequency of a high quality factor(Q)optical cavity facilitates subpicometer displacement measurements of the optical cavity via Pound-Drever-Hall(PDH)locking scheme,tightly synchronizing a laser frequency to the optical *** we present observations of subfemtometer displacements on a ultrahigh-Q single-crystal MgF_(2)whispering-gallery-mode microcavity by frequency synchronization between a 1 Hz cavity-stabilized laser and a resonance of the MgF_(2) cavity using PDH laser-cavity *** characterize not only the displacement spectral density of the microcavity with a sensitivity of 1.5×10^(-16) m/Hz^(1/2) over the Fourier offset frequency ranging from 15 mHz to 100 kHz but also a 1.77 nm displacement fluctuation of the microcavity over 4500 *** measurement capability not only supports the analysis of integrated thermodynamical and technical cavity noise but allows for minute displacement measurements using laser-cavity locking for ultraprecise positioning,metrology,and sensing.

关键词： synchronization displacement cavity

Stability management of high speed axial flow compressor stage through axial extensions of bend skewed casing treatment

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propulsion and Power Research 2016年第3期5卷 236-249页

作者： Dilipkumar Bhanudasji Alone S.Satish Kumar Shobhavathy M.Thimmaiah Janaki Rami Reddy Mudipalli A.M.Pradeep Srinivasan Ramamurthy Venkat S.Iyengara propulsion division CSIR-NALBangalore 560037India Aerospace Engineering Department IIT BombayPowai 400076India NCAD CSIR-NALBangalore 560017India

This paper presents the experimental results to understand the performance of moderately loaded high speed single stage transonic axial flow compressor subjected to various configurations of axial extensions of bend skewed casing treatment with moderate *** bend skewed casing treatment of 33%porosity was coupled with rectangular plenum chamber of depth equal to the slots *** five axial extensions of 20%,40%,60%,80%and 100%were used for the experimental evaluations of compressor *** main objective was to identify the optimum extension of the casing treatment with reference to rotor leading edge which results in maximum stall margin improvements with minimum loss in the stage *** each axial extension the compressor performance is *** improvement in the stall margin was very significant at some axial extensions with 4%–5%penalty in the stage *** compressors stage shows recovery in terms of efficiency at lower axial extensions of 20%and 40%with increase in the peak stage *** of flow parameters showed the typical behaviors at near stall flow *** wire sensor was placed at the rotor upstream in the tip region to capture the oscillations in the inlet axial and tangential velocities at stall *** the absence of casing treatment the compressor exhibit abrupt stall with very high oscillations in the inlet axial and tangential velocity of the *** extents of oscillations reduce with bend skewed casing *** measurements were also performed in the plenum chamber and salient results are presented in this paper.

关键词： High speed compressor Bend skewed casing treatments Axial extensions Stall margin improvements Peak stage efficiency Hot wire probe Stall Abrupt

The Design and Performance of a High Temperature Rise Combustor for Wind Tunnel

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Journal of Thermal Science 2011年第6期20卷 556-562页

作者： Zhang Rongchun Fan Weijun National Key Laboratory on Aero-Engines School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100191 China

A high-temperature-rise combustor that can be used in high-temperature wind tunnel is introduced in this *** kerosene is used in this type of combustor,with division combustion scheme and evaporator fuel-supply device *** the performance test under atmospheric pressure,when the inlet temperature is 500K and air flow is within the range of 1.5-3.0 kg/s,the outlet temperature can be precisely regulated within the range of ***,higher uniformity of outlet temperature distribution and higher combustion efficiency can be *** the long-time working in the wind tunnel,various components of the combustor,especially the combustor liners are checked without finding any anomaly such as thermal deformation.

关键词：性能测试燃烧室温度上升风洞设计出口温度航空煤油燃料供应

Electrical properties of sub-100nm SiGe nanowires

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Journal of Semiconductors 2016年第10期37卷 10-15页

作者： B.Hamawandi M.Noroozi G.Jayakumar A.Ergül K.Zahmatkesh M.S.Toprak H.H.Radamson Functional Materials division Department of Materials and Nano Physics KTH Royal Institute of Technology Department of Integrated Devices and Circuits KTH Royal Institute of Technology Jet propulsion Laboratory California Institute of Technology

In this study, the electrical properties of Si Ge nanowires in terms of process and fabrication integrity,measurement reliability, width scaling, and doping levels were investigated. Nanowires were fabricated on Si Geon oxide（SGOI） wafers with thickness of 52 nm and Ge content of 47%. The first group of Si Ge wires was initially formed by using conventional I-line lithography and then their size was longitudinally reduced by cutting with a focused ion beam（FIB） to any desired nanometer range down to 60 nm. The other nanowire group was manufactured directly to a chosen nanometer level by using sidewall transfer lithography（STL）. It has been shown that the FIB fabrication process allows manipulation of the line width and doping level of nanowires using Ga *** resistance of wires thinned by FIB was 10 times lower than STL wires which shows the possible dependency of electrical behavior on fabrication method.

关键词： SiGe FIB STL pattern transfer lithography nanowires