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An experimental study of noise generated by tandem blades

Chinese Journal of Aeronautics 2025年第2期38卷 143-160页

作者： Xiaolong TANG Fan TONG Chao WANG Jue DING Guangming LI Xiaoquan YANG Shanghai Institute of Applied Mathematics and Mechanics Shanghai Frontier Science Center of MechanoinformaticsShanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China Key Laboratory of Aerodynamic Noise Control China Aerodynamics Research and Development CenterMianyang 621000China Equipment Design and Testing Technology Research Institute China Aerodynamics Research and Development CenterMianyang 621000China

To facilitate the low-noise design of tandem lift bodies as applied in aeroengines and aircraft,the acoustic features of tandem blades are investigated by wind-tunnel *** is further specialized for the rotating blades applied in contra-rotating open rotors under the concept of frozen-rotor.A 70-channel phased microphone array and nine high-precision free-field microphones are *** beamforming method,enhanced by a source filtering technique,is employed to locate noise sources,providing insights into the source patterns of blade-blade interaction noise concerning flow speed,blade spacing,and aft blade *** results show the following:(A)Sources of tandem-blade noise exist in the form of concentrated source clusters,resulting in two major clusters:the mid-span interaction noise and the tip-induced noise.(B)These source clusters tend to separate as flow speed or blade spacing increases.(C)By increasing blade spacing,the band-pass filtered overall sound pressure level is reduced by 2.9 dB.(D)A two-phase noise suppression pattern is observed with blade clipping,resulting in a total reduction of 3.0 dB for the interaction noise through the removal of tip-induced noise sources and the replacement of mid-span noise *** on these findings,suggestions concerning blade spacing and clipping are discussed.

关键词： Tandem blades Contra-rotating open rotor Noise Beamforming Blade spacing and clipping Wind tunnel test

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Development of a spatial accuracy compensation method based on multi-beam laser interferometer

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Scientific Reports 2025年第1期15卷 1-12页

作者： Lei, Lihua Sun, Changjian Xie, Zhangning Liang, Lijie Fu, Yunxia Zhang, Bo Shanghai Institute of Measurement and Testing Technology Shanghai 201203 China Shanghai Key Laboratory of Online Test and Control Technology Shanghai 201203 China Renishaw (Shanghai) Trading Co Ltd Shanghai 200436 China

A mathematical model has been established for the error associated with the degree of freedom for each motion axis, with a correction applied based on the 12-line method in three-dimensional space. A multi-beam laser interferometer is proposed, which comprises four lasers, where different laser combinations can be used to measure different parameters, ultimately achieving simultaneous measurement of errors for the six degrees of freedom. This has informed the development of a spatial error measurement and accuracy compensation system. The error in the X/Y/Z axis data of the computer numerical control (CNC) machine tool is determined using the multi-beam laser interferometer. Spatial accuracy compensation is achieved by applying a software algorithm, and the positioning accuracy is obtained by measuring the same axis at different spatial coordinate positions to verify correction of the angular error. The experimental results have confirmed that after spatial error compensation, linear positioning accuracy, horizontal and vertical straightness errors were improved by nearly 96%, 89% and 55% respectively;the average and maximum deviations of positioning accuracy were improved by nearly 88% and 91% respectively. © The Author(s) 2025.

关键词： Accuracy Error compensation Laser interferometer Spatial positioning

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Designing Electronic Structures of Multiscale Helical Converters for Tailored Ultrabroad Electromagnetic Absorption

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Nano-Micro Letters 2025年第1期17卷 439-455页

作者： Zhaobo Feng Chongbo Liu Xin Li Guangsheng Luo Naixin Zhai Ruizhe Hu Jing Lin Jinbin Peng Yuhui Peng Renchao Che Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle School of Environmental and Chemical EngineeringNanchang Hangkong UniversityNanchang 330063People’s Republic of China School of Physics and Materials Nanchang UniversityNanchang 330031People’s Republic of China Key Laboratory of Nondestructive Testing Ministry of EducationNanchang Hangkong UniversityNanchang 330063People’s Republic of China Laboratory of Advanced Materials Shanghai Key Lab of Molecular Catalysis and Innovative MaterialsAcademy for Engineering and TechnologyFudan UniversityShanghai 200438People’s Republic of China

Atomic-scale doping strategies and structure design play pivotal roles in tailoring the electronic structure and physicochemical property of electromagnetic wave absorption(EMWA)***,the relationship between configuration and electromagnetic(EM)loss mechanism has remained ***,drawing inspiration from the DNA transcription process,we report the successful synthesis of novel in situ Mn/N co-doped helical carbon nanotubes with ultrabroad EMWA *** calculation and EM simulation confirm that the orbital coupling and spin polarization of the Mn–N4–C configuration,along with cross polarization generated by the helical structure,endow the helical converters with enhanced EM *** a result,HMC-8 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.13 dB at an ultralow thickness of 1.29 *** precise tuning of the graphite domain size,HMC-7 achieves an effective absorption bandwidth(EAB)of 6.08 GHz at 2.02 mm ***,constructing macroscale gradient metamaterials enables an ultrabroadband EAB of 12.16 GHz at a thickness of only 5.00 mm,with the maximum radar cross section reduction value reaching 36.4 dB *** innovative approach not only advances the understanding of metal–nonmetal co-doping but also realizes broadband EMWA,thus contributing to the development of EMWA mechanisms and applications.

关键词： Metal-nonmetal co-doping 3d-2p orbital coupling Spin polarization Helical structure Broadband EM wave absorption

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An experimental study of noise generated by tandem blades

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Chinese Journal of Aeronautics 2025年第2期 147-164页

作者： Xiaolong TANG Fan TONG Chao WANG Jue DING Guangming LI Xiaoquan YANG Shanghai Institute of Applied Mathematics and Mechanics Shanghai Frontier Science Center of MechanoinformaticsShanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai University Key Laboratory of Aerodynamic Noise Control China Aerodynamics Research and Development Center Equipment Design and Testing Technology Research Institute China Aerodynamics Research and Development Center

To facilitate the low-noise design of tandem lift bodies as applied in aeroengines and aircraft, the acoustic features of tandem blades are investigated by wind-tunnel experiments. This is further specialized for the rotating blades applied in contra-rotating open rotors under the concept of frozen-rotor. A 70-channel phased microphone array and nine high-precision free-field microphones are employed. The beamforming method, enhanced by a source filtering technique, is employed to locate noise sources, providing insights into the source patterns of blade-blade interaction noise concerning flow speed, blade spacing, and aft blade clipping. The results show the following:(A) Sources of tandem-blade noise exist in the form of concentrated source clusters,resulting in two major clusters: the mid-span interaction noise and the tip-induced noise.(B) These source clusters tend to separate as flow speed or blade spacing increases.(C) By increasing blade spacing, the band-pass filtered overall sound pressure level is reduced by 2.9 dB.(D) A twophase noise suppression pattern is observed with blade clipping, resulting in a total reduction of3.0 d B for the interaction noise through the removal of tip-induced noise sources and the replacement of mid-span noise sources. Based on these findings, suggestions concerning blade spacing and clipping are discussed.

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Automatic measurement and calibration of DC current ratio error 8

Automatic measurement and calibration of DC current ratio er...

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8th International Symposium on Test Automation and Instrumentation, ISTAI 2020

作者： Zhou, Liren Pan, Yang Lai, Lei Feng, Jian Zhan, Guozhong Shanghai Key Laboratory of On-line Testing and Control Technology Shanghai Institute of Measurement and Testing Technology Shanghai China

ISBN: (纸本)9781839535635

DC current ratio error is an essential measurement performance of DC current ratio instrument, for example, DC current comparator, DC current transformer and DC current sensor. Error determination contributes to the instrument rational use. Based on the principle of secondary differential current measurement, self-calibration method, equal-ratio calibration method and stage-connection equal-ratio calibration method were put forward according to the characteristics of different calibrated instruments. Then, the actual value and error of DC current ratio were available. Meanwhile, circuit diagrams, calibration process and examples were provided;measurement uncertainty was evaluated. The result shows that the proposed methods meet the calibration requirements of DC current ratio instruments;the expanded uncertainty for the 1 A: 1 A~1000 A: 0.5 A ratio is 1.7×10-8~8.4×10-6. The automatic measurement program can effectively improve the work efficiency. © 2020 Institution of Engineering and technology. All rights reserved.

关键词： Calibration

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Research on a Three-phase Flow Electromagnetic Measurement Method 4

Research on a Three-phase Flow Electromagnetic Measurement M...

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2020 4th International Conference on Energy Material, Chemical Engineering and Mining Engineering, EMCEME 2020

作者： Li, Xuejing Li, Haiyang Shanghai Institute of Measurement and Testing Technology Shanghai Key Laboratory of On-line Testing and Control Technology Shanghai China

For a long time, industrial and agricultural production has a wide range of requirements for energy saving and emission reduction. The flow parameter detection of water/gas/oil three-phase flow is of great significance in the control and optimization of the petroleum industry process. Using the principle of correlation method, a multi-electrode electromagnetic measurement method is designed to measure the three-phase flow. The system has the function of self-detection of the meter zero point. The finite element method is used to calculate and analyze the distribution of sensitive fields inside the flow measurement sensor and the influence of different physical parameters of non-conductive objects on the disturbance characteristics of the flow measurement sensor. And through experiments to prove the feasibility, stability and accuracy of the constructed measurement system. © 2021 Published under licence by IOP Publishing Ltd.

关键词： Flow measurement

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Numerical Study on Magnetic Field Characteristics of Electromagnetic Flowmeter with Small Excitation Module 21

Numerical Study on Magnetic Field Characteristics of Electro...

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5th International Conference on control Engineering and Artificial Intelligence, CCEAI 2021

作者： Yao, Xinhong Li, Xuejing Shanghai Institute of Measurement and Testing Technology Shanghai Key Laboratory of On-line Testing and Control Technology China

ISBN: (纸本)9781450388870

Electromagnetic flowmeter (EMFM) plays an important role in many production processes such as industry, medicine and agriculture. According to the measurement principle, the traditional electromagnetic flowmeter must have a large-size excitation module to provide a uniform magnetic field. However, this structure limits the use of electromagnetic flow meters. The saddle coil design has certain applications in electromagnetic flow sensors. The geometric size of the saddle coil is smaller than the Helmholtz coil and other large coils, so it has certain advantages in practical applications. But it causes the inhomogeneity of the induced magnetic field, which affects the measurement accuracy. This paper analyzes a saddle-shaped excitation module. An extended theory with a small magnetized flowmeter is proposed and compared with the experimental results. The electromagnetic field solution of the finite element program is proposed. The results of this study have certain guiding significance for the design process of the electromagnetic flowmeter excitation coil. © 2021 ACM.

关键词： Magnetic fields

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Study on A-GNSS Terminal Over-The-Air Test System 15

Study on A-GNSS Terminal Over-The-Air Test System

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15th IEEE International Conference on Electronic Measurement and Instruments, ICEMI 2021

作者： Wang, Yunling Cai, Qing Xu, Jie Shanghai Institute of Measurement and Testing Technology Shanghai Key Laboratory of On-line Testing and Control Technology Shanghai China

ISBN: (纸本)9781665444910

The A-GNSS terminal Over-The-Air (OTA) test system is a system for OTA performance of terminals that support A-GNSS. Terminals supporting A-GNSS can search for satellite navigation signals quicker than terminals only supporting GNSS. Active test is to measure the radiant power and receiving sensitivity of terminal over the air in a microwave anechoic chamber, which displays radiation performance of whole terminal obviously. Many test plans for OTA have been released, and among them the most recognized one is released by CITA. The instruments are mainly provided by Spirent and RS. This paper introduces test plans, test situation of network operators and test institutions, compares 2 solutions provided by Spirit and RS, describes test procedures, and simulates sensitivity test process. © 2021 IEEE.

关键词： testing

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Investigation on Sampling Flow Rate Calibration Method of Air Sampler 19

Investigation on Sampling Flow Rate Calibration Method of Ai...

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19th International Flow Measurement Conference 2022, FLOMEKO 2022

作者： Song, Jin Chen, Chao Liu, Yiping Li, Haiyang Shanghai Institute of Measurement and Testing Technology Shanghai Key Laboratory of On-line Testing and Control Technology Shanghai201203 China

ISBN: (纸本)9781713871989

In order to obtain the most accurate and effective sampling flow rate calibration method of air sampler, several different equipments were used under two different installation conditions in this paper. According to the experimental results, the calibration results of ultrasonic flowmeter and special orifice flowmeter will be affected by the installation conditions. Consequently, while ultrasonic flowmeter and special orifice flowmeter are used to sampling flow rate calibration, it is necessary to first calibrate the two flowmeters with filter paper, and then use the corrected results to calibrate the sampling flow rate. Based on the results of further experiments, calibration datas of gas roots flowmeter and special orifice flowmeter are consistent with the results obtained from gas flow standard facilities by negative pressure method, at the same time, there is still an error of 3%~5% when corrected ultrasonic flowmeter is used. Therefore, gas flow standard facilities by negative pressure method and gas roots flowmeter can be directly used for sampling flow rate calibration of air sampler, if it is not convenient, special orifice flowmeter which calibrated with filter paper is also a good choice, ultrasonic flowmeter is not recommended. © FLOMEKO *** rights reserved

关键词： Flow rate

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A Numerical Study on the Influence of Temperature on the Measurement Performance of liquid lead-bismuth-eutectic (LBE) Electromagnetic-flowmeter 19

A Numerical Study on the Influence of Temperature on the Mea...

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19th International Flow Measurement Conference 2022, FLOMEKO 2022

作者： Li, Xuejing Yao, Xinhong Li, Haiyang Shanghai Institute of Measurement and Testing Technology Shanghai China Shanghai Key Laboratory of On-line Testing and Control Technology Shanghai China

ISBN: (纸本)9781713871989

Liquid lead-bismuth eutectic (LBE) is one of the preferred materials for accelerator driven subcritical(ADS) transmutation targets and coolants in fourth-generation nuclear reactors. Due to the complex and interacting physical and chemical factors in the measurement process of LBE in high temperature operating environment, it is very difficult to control the flow and on-line calibration, resulting in the slow development of LBE flow meter technology, which hinders the fourth Generation nuclear reactor technology development. Electromagnetic flowmeter is currently recognized as one of the most suitable LBE flow measuring instruments in the world. In this paper, the measurement characteristics of LBE electromagnetic flowmeter at high temperature are numerically analyzed and studied, the influence of temperature on magnetic field strength and flow field distribution is quantitatively given, and the measurement linearity of LBE electromagnetic flowmeter is analyzed. The research conclusions provide a certain reference for the detection of lead-bismuth alloy flow parameters and the on-line calibration of LBE electromagnetic flowmeters in the nuclear industry control process. © FLOMEKO *** rights reserved

关键词： Nuclear reactors

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