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Comparison of Rotating Stall Warning by Different Methods for Variable Speed Configurations in a Contra-Rotating Compressor

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Journal of Thermal Science 2024年第4期33卷 1379-1393页

作者： XUE Fei WANG Yan'gang liu Qian WU Tong liu hanru School of Power and Energy Northwestern Polytechnical UniversityXi’an710072China

Stall in compressors can cause performance degradation and even lead to *** unacceptable consequences can be avoided by timely monitoring stall inception and taking effective *** paper focused on the rotating stall warning in a low-speed axial contra-rotating ***,the stall disturbance characteristics under different speed configurations were *** results showed that as the speed ratio(RR)increased,the stall disturbance propagation speed based on the rear rotor speed gradually ***,the standard deviation(SD)method,the cross-correlation(CC)method,and the discrete wavelet transform(DWT)method were employed to obtain the stall initiation moments of three different speed *** was found that the SD and CC methods did not achieve significant stall warning results in all three speed ***,the stall initiation moment obtained by the DWT method at RR=1.125 was one period after the stall had fully developed,which was ***,a stall warning method was developed in the present work based on the long short-term memory(LSTM)regression *** applying the LSTM model,the predicted stall initiation moments of three speed configurations were at the 557th,518th,and 333rd revolution,which were44,2,and 74 revolutions ahead of stall onset moments,***,in scenarios where a minor disturbance preceded the stall,the stall warning effect of the LSTM was greatly improved in comparison with the aforementioned three *** contrast,when the pressure fluctuation before the stall was relatively small,the differences between the stall initiation moments predicted by these four methods were not significant.

关键词： contra-rotating compressor stall disturbance stall initiation moment long short-term memory(LSTM) stall warning

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电推进涵道风扇气动快速求解方法及性能分析研究

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推进技术 2024年第3期45卷 131-138页

作者：刘乾刘汉儒尚珣王掩刚西北工业大学动力与能源学院陕西西安710129 中国空气动力研究与发展中心气动噪声控制重点实验室四川绵阳621000

随着绿色航空发展,为了能在设计阶段快速获得涵道风扇气动性能参数和非定常流场特征,有必要开发一种高效的数值求解方法。基于小型电推进风扇内流弱可压和尾迹耗散特性,本文将转子和涵道的面元与尾迹涡粒子耦合,使用面元法求解固壁流场... 详细信息

随着绿色航空发展,为了能在设计阶段快速获得涵道风扇气动性能参数和非定常流场特征,有必要开发一种高效的数值求解方法。基于小型电推进风扇内流弱可压和尾迹耗散特性,本文将转子和涵道的面元与尾迹涡粒子耦合,使用面元法求解固壁流场,使用涡量输运方程求解远场尾迹传播特征,克服了有限体积法尾迹耗散快的问题。研究表明,本文发展的面元-涡粒子耦合方法对涵道风扇叶表压力与有限体积法趋势一致,整体推力误差为7.83%,能满足工程快速预测需求。本文发展的高效非定常计算方法的尾迹计算数值耗散低,能揭示更为复杂的非定常流动现象,仿真结果显示风扇涵道对尾迹发展有明显约束,而当尾迹传播至外部时,涡量呈现出明显的收缩和对称分布特征。在计算效率方面,本文发展的耦合方法非定常计算效率高,计算相同非定常时间步耗时仅为有限体积法的1/6,具有潜在的涵道动力非定常设计应用价值。

关键词：电推进系统涵道风扇面元-涡粒子法非定常气动计算快速预测方法

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Multi-scale nature of non-blade-order propagating flow disturbances in axial compressors

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Chinese Journal of Aeronautics 2022年第9期35卷 129-142页

作者： Hao WANG Yan’gang WANG hanru liu Fei XUE Zhongnan WANG School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China College of Engineering and Physical Sciences University of BirminghamBirmingham B152TTUnited Kingdom

Non-blade-order flow disturbances, also referred to as pre-stall disturbances or tip flow unsteadiness, are closely related with compressor instabilities. The present work provides a comprehensive investigation on multi-scale nature of non-blade-order disturbances and the underlying flow physics in axial compressors. By applying full-annulus Unsteady Reynolds-Averaged Navier-Stokes(URANS) simulations, along with space–time correlation and spatial Fourier decomposition, to the disturbed pressure, the propagating feature of the non-blade-order disturbances is obtained. Further, a bridge between non-blade-order disturbances and the evolution of unsteady vortex has been set up. The results show that non-blade-order disturbances, featured as short-length-scale(35 modes across annulus), first appear as the occurrence of tip leakage vortex fluctuation, while the compressor still operates far from stall. Leading-edge radial vortex appears at near stall condition, and its movement induces a circumferential propagating disturbance overlaying on the one induced by oscillating tip leakage vortex. The interaction of the short-scale disturbances with a lowamplitude long-scale(of circumference) disturbance is observed, which results in disturbances with multiple scales of consecutive spatial modes, along with multiple frequency peaks in spectra. The compressor falls into stall as the circumferential nonuniform scattering of the leading-edge vortexes occurs. The densely-and sparsely-scattered leading-edge radial vortexes induce a high-amplitude long-scale(of circumference) disturbance , i.e. stall disturbance.

关键词： Axial compressors Flow instabilities Multi-scale disturbances Stall Unsteady flow

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涵道风扇部件耦合设计方法及初步应用

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推进技术 2024年第3期45卷 139-148页

作者：王思维王掩刚陈延俊刘汉儒和润生西北工业大学动力与能源学院陕西西安710072 中国航空工业空气动力研究院黑龙江哈尔滨150001

涵道风扇是未来绿色航空动力的重要发展方向,快速、准确的涵道风扇设计方法成为工程领域的迫切需求。在传统的涵道风扇设计方法中,部件间的耦合效应需要建立在完善的三维数值计算或试验数据的基础之上。而本文发展了考虑涵道风扇关键部... 详细信息

涵道风扇是未来绿色航空动力的重要发展方向,快速、准确的涵道风扇设计方法成为工程领域的迫切需求。在传统的涵道风扇设计方法中,部件间的耦合效应需要建立在完善的三维数值计算或试验数据的基础之上。而本文发展了考虑涵道风扇关键部件耦合效应的设计方法,形成了涵道风扇一体化设计手段,并以此为基础开展了涵道风扇的一体化设计及验证工作。结果表明:相比于简单叠加设计方法,耦合设计使叶片推力设计误差由15%减小到3.5%;采用部件耦合方法设计的带有扩张喷管涵道风扇和等直径喷管涵道风扇的转静叶片推力设计误差满足工程需求,确认了部件耦合的设计方法正确传递了部件间的影响关系;通过试验对设计结果进行了推力校验,试验结果与设计点的总推力误差为1.25%,证明了本文发展的耦合设计方法的准确性。

关键词：耦合设计涵道风扇设计方法风扇叶片喷管

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Unsteady Study on the Effects of Matching Characteristic of Tandem Cascade on the Performance and Flow at Large Angle of Attack

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Journal of Thermal Science 2018年第6期27卷 505-515页

作者： liu hanru YUE Shaoyuan WANG Yangang ZHANG Jun School of Power & Energy Northwestern Polyteclmical University Xi'an 710129 China Shaanxi Key Laboratory of Internal Aerodynamics in Acro-Engine Xi'an 710129 China

To investigate the effects of matching characteristics of tandem cascade on the performance and flow at large angle of attack, the unsteady numerical simulation has been implemented. The influences of different turning angle ratio(TR) and chord length ratio(CR) of two blades and the relative angle of attack of rear blade(Delta) are analyzed. The numerical results indicated that the tandem cascade can obtain overall performance improvement including higher static pressure ratio and lower total pressure loss with the matching parameters in the range of TR=3～5, CR=0.5～1.2, and Delta=-15°～-5°. The separation on the front blade has more prominent impact than that on the rear blade, so the performance improvement of tandem cascade is significantly dependent on the reduction of front-blade separation and loss. Regarding the rear blade, the gap injection effect can periodically control the separation. Temporal and spatial analysis of the flow field shows that the optimal-performance cases generally have much smaller wake loss for both two blades, but the unsteady characteristics of the wake loss is more apparent than that of the poor performance cases.

关键词：脚踏车不稳定表演串联攻击特征匹配流动

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Modification of Flow Structure and Sound Source by Hybrid Porous-serrated Trailing Edge

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Journal of Bionic Engineering 2020年第3期17卷 539-552页

作者： hanru liu Nanshu Chen Yangang Wang Zhijie Hu School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Key Laboratory of Aerodynamic Noise Control Mianyang 621000China

The effects of hybrid porous-serrated trailing edge on flow structure and sound source of NACA65(12)-10 at moderate Reynolds number(Rec=5×1O^5)have been investigated by Delayed Detached Eddy Simulation(DDES).Compared with conventional serrated trailing edge,the pressure fluctuation in the vicinity of hybrid porous-serrated trailing edge is further decreased *** typical necklace vortex structures stretching across adjacent serrations are suppressed by the porous *** is found that porous media changes the shear stress distribution along the serration edge and inside the serration gap,which consequently eliminates the generation of necklace ***,the deformation of vortex tube caused by velocity vector is *** underlying mechanisms associated to the sound source modification are analyzed based on vortex sound *** magnitude of Lamb vector and the angle between vorticity and velocity vectors are synchronously reduced by the porous additive,which implies that the present hybrid porous-serrated trailing edge has important influence on the further attenuation of far-field aerodynamic noise.

关键词： bionic flow control wake modification hybrid porous-serration vortex sound theory noise reduction

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Reduced order model for unsteady aerodynamic performance of compressor cascade based on recursive RBF

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Chinese Journal of Aeronautics 2021年第4期34卷 341-351页

作者： Jiawei HU hanru liu Yan'gang WANG Weixiong CHEN Yan MA School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China Yangtze River Delta Research Institute Northwestern Polytechnical UniversityTaicang 215400China

Based on Recursive Radial Basis Function(RRBF)neural network,the Reduced Order Model(ROM)of compressor cascade was established to meet the urgent demand of highly efficient prediction of unsteady aerodynamics performance of *** novel ROM called ASA-RRBF model based on Adaptive Simulated Annealing(ASA)algorithm was developed to enhance the generalization ability of the unsteady *** ROM was verified by predicting the unsteady aerodynamics performance of a highly-loaded compressor *** results show that the RRBF model has higher accuracy in identification of the dimensionless total pressure and dimensionless static pressure of compressor cascade under nonlinear and unsteady conditions,and the model behaves higher stability and computational ***,for the strong nonlinear characteristics of aerodynamic parameters,the RRBF model presents lower ***,the RRBF model predicts with a large error in the identification of aerodynamic parameters under linear and unsteady *** ASA-RRBF,by introducing a small-amplitude and highfrequency sinusoidal signal as validation sample,the width of the basis function of the RRBF model is optimized to improve the generalization ability of the ROM under linear unsteady ***,this model improves the predicting accuracy of dimensionless static pressure which has strong nonlinear *** ASA-RRBF model has higher prediction accuracy than RRBF model without significantly increasing the total time *** novel model can predict the linear hysteresis of dimensionless static pressure happened in the harmonic condition,but it cannot accurately predict the beat frequency of dimensionless total pressure.

关键词： Compressor cascade Neural network Recursive radial basis function Reduced order model Unsteady flow

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多孔介质流动控制及气动降噪研究进展

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航空学报 2023年第16期44卷 1-21页

作者：刘汉儒陈南树刘宇胡之颉西北工业大学动力与能源学院西安710129 南方科技大学力学与航空航天工程系深圳518055

流动控制是空气动力学中的重要研究领域,这一技术将成为未来飞行器及动力装置气动增益设计的新手段。来源于仿生学的多孔介质处理是一种方兴未艾的被动流动控制技术,其在流动控制和气动噪声降低方面具有重要潜力。首先,对多孔介质应用... 详细信息

流动控制是空气动力学中的重要研究领域,这一技术将成为未来飞行器及动力装置气动增益设计的新手段。来源于仿生学的多孔介质处理是一种方兴未艾的被动流动控制技术,其在流动控制和气动噪声降低方面具有重要潜力。首先,对多孔介质应用于流动及噪声控制的起源与动机进行了回顾;其次,阐述了不同多孔介质的构型和模型化方法;随后,基于国内外相关研究工作,探讨了多孔介质在钝体外流、孤立叶片、旋转机械流动调控和气动噪声降低方面的结构设计和应用效果。目前国内外的研究表明,多孔介质在合适的结构设计、材料物性和工况下具有较好的流动改善和降噪能力。但是,目前还没有成熟的设计理论指导应用以及更广泛的适用条件研究。跨尺度的流动耦合研究和涡动力学研究对于深入理解多孔介质的流动根源改变和降噪机制至关重要,进一步的优化设计多孔介质内部构型、表观参数和设计形式是这种流动控制降噪技术未来应用于工程而亟需开展的重要工作。

关键词：多孔介质被动流动控制气动声学噪声控制叶轮机械噪声

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周期性冬灌对新疆膜下滴灌棉田盐分和经济效益的影响

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干旱区资源与环境 2022年第6期36卷 194-201页

作者：刘函如冯进平刘洪光石河子大学工会石河子832000 石河子大学水利建筑工程学院石河子832000 现代节水灌溉兵团重点实验室石河子832000

为探究周期性冬灌对长期膜下滴灌棉田盐分变化及棉花成活率和产量的影响规律,以长期膜下滴灌结合非生育期周期性冬灌模式的农田为例,监测棉田全生育期及非生育期盐分含量、棉苗成活率和棉花产量。研究结果表明:周期性冬灌对盐分淋洗效... 详细信息

为探究周期性冬灌对长期膜下滴灌棉田盐分变化及棉花成活率和产量的影响规律,以长期膜下滴灌结合非生育期周期性冬灌模式的农田为例,监测棉田全生育期及非生育期盐分含量、棉苗成活率和棉花产量。研究结果表明:周期性冬灌对盐分淋洗效果明显,继续耕作盐分会有小幅度上升;该模式应用7a后,土壤盐含量基本稳定在一个较低水平内。2008年0~150cm观测层盐分质量分数为10~65g/kg,至2019年4次冬灌后下降到了3g/kg以下。周期性冬灌后0~20cm返盐最为明显,次年继续耕作至收获时返盐率均>40%。棉花成活率和产量成正比,且冬灌对其影响显著,2019年成活率和产量最高分别可达94.3%和7216.8kg/hm^(2)。采用该模式应用4年后,棉田成活率>60%,农田收支比大于1%。文中旨在探明周期性冬灌的条件下盐分长期变化规律,为农业可持续发展、盐碱地开发和改良提供理论依据和技术支持。

关键词：周期性冬灌膜下滴灌盐分变化经济效益

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Imiquimod:A potential option for inhibition of repigmentation of congenital melanocytic nevus after laser ablation

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Chinese Journal of Plastic and Reconstructive Surgery 2024年第2期6卷 76-78页

作者： Yifei Zhao Yun Zou Xiangyu Chen Hanlin Zeng hanru Ying Xiaoxi Lin Hui Chen Department of Plastic and Reconstructive Surgery Shanghai Ninth People's Hospital Shanghai Jiao Tong University School of Medicine Shanghai Institute of Precision Medicine Shanghai Ninth People's Hospital Shanghai Jiao Tong University School of Medicine Department of Oncology Shanghai Ninth People's Hospital Shanghai Jiao Tong University School of Medicine

Congenital melanocytic nevi(CMN) are common skin tumors. Large and specially located nevi cannot be completely removed by surgery, posing the risks of both cosmetic deformities and potential *** treatments, such as laser therapy and physical dermabrasion, can overcome the limitations of surgery;however, the high rate of repigmentation remains an unresolved global challenge. We conducted a self-controlled observational study of a patient with a nevus on the chest. Two areas of the lesion were treated with an Er:YAG laser and 5% imiquimod cream was applied to one of these areas. After nearly 7-months of follow-up, we observed a significant difference in color between the two areas, suggesting that topical imiquimod may inhibit repigmentation and significantly enhance the effectiveness of laser treatment.

关键词： Imiquimod Congenital melanocytic nevus Recurrence Laser

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