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Effect of wire mesh casing treatment on axial compressor performance and stability

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Chinese Journal of Aeronautics 2024年第3期37卷 60-76页

作者： Ming ZHANG Jiaming ZHANG Jiahao HU Xu DONG Dakun sun xiaofeng sun School of Energy and Power Engineering Beihang UniversityBeijing 100191China Beihang Hangzhou Innovation Institute Yuhang Hangzhou 310023China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China

In this paper,a kind of Wire Mesh Casing Treatment(WMCT)is proposed to improve the stable operating range of the *** contrast to the traditional circumferential groove,as for WMCT,a layer of wire mesh is laid on the surface of the circumferential *** studies were conducted on the low-speed axial flow compressor,including the groove width,axial location,and mesh *** optimum axial location for WMCT is related to its groove width.A higher wire mesh count results in a smaller compressor stall margin *** simulations were carried out to study the effect of WMCT on the flow structure of the *** wire mesh in the WMCT has a certain flow resistance,which restricts the flow into and out of the *** to the WMCT,the flow parameter in the tip region of the rotor is less sensitive to changes in the operating conditions of the *** WMCT causes the rotor tip blade loading to shift backward,inhibiting the formation of spill forward of the leakage flow,and thus improving the stability of the *** flow resistance on the groove surface is a new degree-of-freedom for the casing treatment designer.

关键词： Axial compressor Wire mesh casing treatment Tip clearance flow Stall margin Blade loading

Limits of Uneven Battery Power in Modular Multilevel Converter-based Battery Energy Storage Systems

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 686-695页

作者： Yao Pan xiaofeng sun Wei Zhao Xin Li Yao Cai Institute of Electrical Engineering Yanshan UniversityQinhuangdao 066004China

For modular multilevel converter-based battery energy storage systems (MMC-BESS), uneven power among batteries of SMs will be deduced by battery aging, battery fault, etc., which will degrade performance and even lead to system failure. For maintaining the balance of capacitor voltage, this paper analyzes the limits of the uneven power of batteries, which are presented as the current limits in this paper. According to analysis, an analytical method is proposed that only the dc and fundamental frequency components of the arm current are used to calculate current limits. With the current limits it is able to evaluate the reasonability of power distribution among batteries. Meanwhile, increase of fundamental frequency component will enhance the current limits, and the dc component determines the size relationship between the absolute values of the upper and lower current limits. Finally, simulation model and experiment prototype are built for verifying the theoretical analysis and current limits calculation method, and satisfactory results are provided.

关键词： Arm current balance of capacitor voltage current limits MMC-BESS uneven power

Non-synchronous vibration of rotor blade in a six-stage transonic compressor

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Chinese Journal of Aeronautics 2024年第8期37卷 36-48页

作者： Ronghui CHENG Zhuo WANG Huawei YU Lin DU Yi ZHANG xiaofeng sun Aeroengine Research Institute Beihang UniversityBeijing 102206China School of Energy and Power Engineering Beihang UniversityBeijing 102206China

This paper presents an experimental study on the Non-Synchronous Vibration(NSV)in a six-stage transonic *** first part of the paper describes the NSV phenomenon of Rotor 1,which occurs when both Stator 1(S1)and Stator 2(S2)or S1 only are *** measurements and analysis are carried out for the former case through the unsteady wall pressure and the Blade Strain(BS).The spinning mode theory used in the rotor/stator interaction noise is employed to explain the relation between the circumferential wave number of the aerodynamic disturbance and the Nodal Diameter(ND)of the blade *** variations of the vibration amplitudes of different blades and the Inter-Blade Phase Angles(IBPAs)at different moments suggest that the evolution of NSV is a highly nonuniform phenomenon along the circumferential *** addition,the difference between the wall-pressure spectra generated by the NSV and the classic flutter has been *** the second part,the variations of aerodynamic loading due to the adjustment of the staggers of the Inlet Guide Vane(IGV),S1 and S2 have been *** is found that closing S1 only can result in a great fluctuation to the performance of the front stages,which might be detrimental to the flow organization and increase the risk of *** contrast,the effect of closing S2 only on the performance of the first two stages appears to be slighter relatively.

关键词： Transonic compressor Non-synchronous vibration Modal analysis Aerodynamic loading Nodal diameter

Broadband intelligent programmable metasurface with polarization-modulated self-adaptive electromagnetic functionality switching

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Photonics Research 2024年第7期12卷 1395-1409页

作者： XIMING LI RUI XU xiaofeng sun YUAN ZHAO ZHAO YANG GUOHONG DU College of Electronic Engineering Chengdu University of Information TechnologyChengdu 610225China

Programmable metasurfaces have received a great deal of attention due to their ability to dynamically manipulate electromagnetic(EM) waves. Despite the rapid growth, most of the existing metasurfaces require manual control to switch among different functionalities, which poses severe limitations on practical applications. Here, we put forth an intelligent metasurface that has self-adaptive EM functionality switching in broadband without human participation. It is equipped with polarization discrimination antennas(PDAs) and feedback components to automatically adjust functionalities for the different incident polarization information.

关键词： equipped adjust polarization

A Methodology for Assessing Axial Compressor Stability with Inlet Temperature Ramp Distortion

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Journal of Thermal Science 2024年第3期33卷 856-871页

作者： sun Dakun GU Benhao NING Fangfei FANG Yibo DONG Xu XU Dengke sun xiaofeng School of Energy and Power Engineering Beihang UniversityBeijing102206China Research Institute of Aero-engine Beihang UniversityBeijing102206China

Based on a small perturbation stability model for periodic flow,the effects of inlet total temperature ramp distortion on the axial compressor are investigated and the compressor stability is quantitatively *** the beginning,a small perturbation stability model for the periodic flow in compressors is proposed,referring to the governing equations of the Harmonic Balance *** stability model is validated on a single-stage low-speed compressor TA36 with uniform inlet ***,the unsteady flow of TA36 with different inlet total temperature ramps and constant back pressure is simulated based on the Harmonic Balance *** on these simulations,the compressor stability is analyzed using the proposed small perturbation ***,the Dynamic Mode Decomposition method is employed to accurately extract pressure *** two parameters of the temperature ramp,ramp rate and Strouhal number,are discussed in this *** results indicate the occurrence and extension of hysteresis loops in the rows,and a decrease in compressor stability with increasing ramp *** performance is divided into two phases,stable and limit,based on the ramp ***,the model predictions suggest that a decrease in period length and an increase in Strouhal number lead to improved compressor *** DMD results imply that for compressors with inlet temperature ramp distortion,the increase of high-order modes and oscillations at the rotor tip is always the signal of decreasing stability.

关键词： axial compressor stability small perturbation model inlet temperature ramp distortion harmonic balance method dynamic mode decomposition method

Carbon dot-based artificial light-harvesting systems with sequential energy transfer and white light emission for photocatalysis

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Chinese Chemical Letters 2024年第4期35卷 409-413页

作者： Chaoqun Ma Yuebo Wang Ning Han Rongzhen Zhang Hui Liu xiaofeng sun Lingbao Xing School of Chemistry and Chemical Engineering Shandong University of TechnologyZibo 255000China Department of Materials Engineering KU LeuvenLeuven 3001Belgium

In this work, we designed and synthesized cationic carbon dots(CDs) with a size distribution of 1.6–3.7 nm, which exhibited dark blue fluorescence in the aqueous solution. Based on its excellent luminescence properties, we used it as an energy donor to construct a sequential artificial light-harvesting system(LHS) by employing the energy-matching dyes eosin Y disodium salt(EY) and sulforhodamine101(SR101), which could regulate the white light emission(Commission Internationale de l'Eclairage(CIE) coordinate:(0.30, 0.31)) with the energy transfer efficiency(ΦET) of 53.9% and 20.0%. Moreover, a single-step artificial LHS with white light emission(0.32, 0.28) can be constructed directly using CDs and dye solvent 43(SR) with ΦETand antenna effect(AE) of 48.8% and 6.5, respectively. More importantly,CDs-based artificial LHSs were firstly used in photocatalytic of α-bromoacetophenone, with a yield of90%. This work not only provides a new strategy for constructing CDs-based LHSs, but also opens up a new application for further applying the energy harvested in CDs-based LHSs to the field of the aqueous solution photocatalysis.

关键词： Carbon dots White light emission Energy transfer Antenna effect Artificial light-harvesting system Photocatalysis

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非定常涡升力机制的三维效应

工程热物理学报 2024年第2期45卷 410-417页

作者：王卓杜林孙晓峰北京航空航天大学航空发动机研究院北京100191

本文采用浸入式边界方法对一低速单级压气机在不同轴向间距下的转静干涉流动进行了数值模拟,主要关注缩小轴向间距后由于非定常涡升力机制所引起的前后排叶片流动状态变化。计算结果表明,级性能随间距出现提升的流动机理在于,当间距减小... 详细信息

本文采用浸入式边界方法对一低速单级压气机在不同轴向间距下的转静干涉流动进行了数值模拟,主要关注缩小轴向间距后由于非定常涡升力机制所引起的前后排叶片流动状态变化。计算结果表明,级性能随间距出现提升的流动机理在于,当间距减小后,前排转子的负荷出现提升,这一变化使得级间静压升高,静子根部的逆压梯度得到有效的缓解,进而导致静子根部的流动分离被抑制,压气机的压升及效率均出现明显的提升。

关键词：转静干涉非定常涡升力浸入式边界方法

基于浸入式边界方法的圆柱-振荡翼型流动干涉数值模拟研究

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Acta Mechanica Sinica 2024年第4期40卷 136-158页

作者：王卓杜林孙晓峰 Aeroengine Research Institute Beihang UniversityBeijing100191China School of Energy and Power Engineering Beihang UniversityBeijing100191China

本文研究了圆柱尾迹中振荡翼型的动力学特性,通过浸入式边界方法结合自适应网格技术对雷诺数为1100的二维模型开展了数值模拟计算,重点关注圆柱翼型间距和振荡频率这两个关键参数的影响.文中给出了翼型动力学响应随上述两个参数的变化规... 详细信息

本文研究了圆柱尾迹中振荡翼型的动力学特性,通过浸入式边界方法结合自适应网格技术对雷诺数为1100的二维模型开展了数值模拟计算,重点关注圆柱翼型间距和振荡频率这两个关键参数的影响.文中给出了翼型动力学响应随上述两个参数的变化规律,包括流动作用力、频率特征以及翼型与流动之间的能量交换过程,结果表明圆柱尾迹能够显著改变翼型阻力的大小,并且对通过翼型升力所产生的能量交换过程具有重要影响.在某些特定流动工况下,翼型振荡会与尾迹之间呈现出1:1,1:2和1:3不同的同步模式.值得注意的是,1:2同步对应着一种非对称的涡脱落形态,在此工况下,即使翼型的振荡和上游圆柱尾迹都存在明显的周期性,翼型上依然存在非零的时均升力及力矩.此外由于圆柱尾迹与翼型振荡之间的强烈非线性干涉,在翼型响应中出现了新的频率条带,该条带满足非线性频率叠加关系.本文还发现振荡幅值对于同步现象具有重要影响.

关键词：自适应网格技术振荡翼型能量交换过程圆柱尾迹动力学响应频率特征非线性频率涡脱落

一种拓展模块化多电平变换器的光伏系统稳定运行范围的谐波补偿调制策略

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电工技术学报 2024年第4期39卷 1132-1146页

作者：潘尧孙孝峰蔡瑶李昕赵巍燕山大学电力电子节能与传动控制河北省重点实验室秦皇岛066004

由于阴影遮挡、损坏等问题,基于模块化多电平变换器的光伏系统中存在光伏(PV)输出功率不平衡的现象,会使高输出功率PV对应的子模块过调制。谐波补偿调制策略是解决该问题的一种常见方案,通过向高功率PV的子模块中注入谐波而避免子模块... 详细信息

由于阴影遮挡、损坏等问题,基于模块化多电平变换器的光伏系统中存在光伏(PV)输出功率不平衡的现象,会使高输出功率PV对应的子模块过调制。谐波补偿调制策略是解决该问题的一种常见方案,通过向高功率PV的子模块中注入谐波而避免子模块过调制,低功率PV的子模块(称为正常子模块)则需要补偿数量相同、相位相反的谐波,使桥臂内的谐波相抵消而不会造成桥臂电压和电流畸变。然而,在PV功率严重不平衡时,为了避免高功率PV的子模块过调制,现有谐波补偿调制策略需要注入的谐波过大,会超过正常子模块的补偿范围,使正常子模块出现过调制,导致桥臂电压和电流畸变,影响系统的稳定运行。该文提出一种新型谐波补偿调制策略,在高功率PV的子模块不发生过调制的前提下避免正常子模块过调制,保证系统的稳定运行。同时,该文对不同谐波补偿调制策略稳定运行范围进行了定性和定量评估,表明所提谐波补偿调制策略能在更多PV功率不平衡工况下稳定运行。通过仿真与实验验证谐波补偿调制策略在模块化多电平变换器光伏系统中的可行性与理论分析的正确性。

关键词：模块化多电平变换器功率不平衡谐波补偿调制策略过调制稳定运行