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Pressure Analysis of the Initial Process of Diffusion Combustion surge in a 350 kW Gas Boiler

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Journal of Thermal Science 2022年第2期31卷 582-589页

作者： GAO Han ZHU Tong PAN Deng School of Mechanical Engineering Tongji UniversityShanghai 201804China

In order to meet the increasingly stringent requirements for nitrogen oxides(NOx)emissions from gas boilers,flue gas recirculation(FGR)technology is commonly used to achieve ultra-low NOx emissions.However,under some ultra-low NOx combustion conditions with FGR,a surge phenomenon occurs in the boiler,which causes a flameout and should be avoided.In this study,the diffusion combustion surge of gas boiler with a rated power of 350 k W and equipped with FGR device was investigated.Pressure characteristic analysis results of the initial process of combustion surge showed that the high-frequency component of pressure is closely related to combustion stability and its change can provide reference for the occurrence of surge.Besides,the initial process of surge was analyzed by wavelet packet entropy method.Results indicated that the wavelet packet entropy of pressure signals could effectively reflect the stability of combustion in the furnace,and it could also be used to study the occurrence of surge.

关键词： diffusion combustion flue gas recirculation wavelet packet entropy surge gas boiler

Transition from Unsteady Flow Inception to Rotating Stall and surge in a Transonic Compressor

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Journal of Thermal Science 2022年第1期31卷 120-129页

作者： CAO Dongming YUAN Caijia WANG Dingxi HUANG Xiuquan Shaanxi Key Laboratory of Internal Aerodynamics in Aero-Engines Northwestern Polytechnical UniversityXi’an 710072China

Since the transition from rotating stall to surge in a transonic compressor at high speed is very quick,quite often there is no time to take measures to prevent the surge.Therefore,it is desired to find any rotating stall precursors,of which the occurrence can offer sufficient time for stall or surge prevention.In this study,a series of unsteady flow analyses were performed on a transonic compressor under operating conditions before rotating stall with unsteady results scrutinized to find rotating stall precursors.Particular attention is paid to the spatial modes and time modes of static pressure near the casing and around the blade leading and trailing edges.The results show that the characteristics of the precursor in both spatial and time domains can be used as rotating stall warnings.

关键词： transonic compressor unsteady flow precursor rotating stall surge

A Review on Theoretical and Numerical Research of Axial Compressor surge

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Journal of Thermal Science 2023年第1期32卷 254-263页

作者： ZHAO Hongliang DU Juan ZHANG Wenqiang ZHANG Hongwu NIE Chaoqun School of Energy Power and Mechanical Engineering North China Electric Power UniversityBeijing 102206China Advanced Gas Turbine Laboratory Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China Key Laboratory of Advanced Energy and Power Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China Innovation Academy for Light-Duty Gas Turbine Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of Mechatronical Engineering Beijing Institute of TechnologyBeijing 100081China

surge is an unstable operating condition of the aero-engine that can move the engine into a destabilized state and cause devastating damage.One of the most popular topics in the academic and industrial communities is to figure out the mechanism of the surge and withdraw from the surge safely.Based on rig test results and practical data from engine operation,various theories of surge mechanisms have been proposed by researchers,and some classical analytical models have been developed for modelling and prediction.In recent years,with the rapid development of numerical simulation and the improvement of computational capability,computational fluid dynamics(CFD)has been widely applied to the investigation of axial compressor surge events.In this review,the principles and general characteristics of the surge phenomenon are first introduced.Subsequently,the main theoretical models and CFD simulations are presented,and their advantages and disadvantages are discussed.In conclusion,we have proposed potential improvements and future technical routes for the surge phenomenon.The purpose of this paper is to provide a valuable reference for surge studies on axial compressors.

关键词： axial compressor surge theoretical numerical CFD

Aero-Engine surge Fault Diagnosis Using Deep Neural Network

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Computer Systems Science & Engineering 2022年第7期42卷 351-360页

作者： Kexin Zhang Bin Lin Jixin Chen Xinlong Wu Chao Lu Desheng Zheng Lulu Tian School of Computer Science Southwest Petroleum UniversityChengdu610500China Sichuan Normal University Chengdu610066China AECC Sichuan Gas Turbine Establishment MianYang621700China Brunel University London UxbridgeMiddlesexUB83PHUnited Kingdom

Deep learning techniques have outstanding performance in feature extraction and modelﬁtting.In theﬁeld of aero-engine fault diagnosis,the intro-duction of deep learning technology is of great signiﬁcance.The aero-engine is the heart of the aircraft,and its stable operation is the primary guarantee of the aircraft.In order to ensure the normal operation of the aircraft,it is necessary to study and diagnose the faults of the aero-engine.Among the many engine fail-ures,the one that occurs more frequently and is more hazardous is the wheeze,which often poses a great threat toﬂight safety.On the basis of analyzing the mechanism of aero-engine surge,an aero-engine surge fault diagnosis method based on deep learning technology is proposed.In this paper,key sensor data are obtained by analyzing different engine sensor data.An aero-engine surge data-set acquisition algorithm(ASDA)is proposed to sample the fault and normal points to generate the training set,validation set and test set.Based on neural net-work models such as one-dimensional convolutional neural network(1D-CNN),convolutional neural network(RNN),and long-short memory neural network(LSTM),different neural network optimization algorithms are selected to achieve fault diagnosis and classiﬁcation.The experimental results show that the deep learning technique has good effect in aero-engine surge fault diagnosis.The aero-engine surge fault diagnosis network(ASFDN)proposed in this paper achieves better results.Through training,the network achieves more than 99%classiﬁcation accuracy for the test set.

关键词： Aero-engine fault diagnosis surge vibration signal classiﬁcation deep learning

Metaverse Upsurge Drives Virtual Human Industry to Upgrade

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China's Foreign Trade 2024年第1期 51-52页

作者： Yu Li 不详

The concept of a virtual human is rapidly fermenting with the boom of the metaverse in 2020.In March 2021,Roblox,a game company focusing on the socialization of teenagers’games and the free realization of UGC,went public.In its prospectus,Roblox is defined as the concept of the metaverse.Under this background,as the direct embodiment of“virtual identity”and“virtual reality coexisting”under the concept of the metaverse,the emerging definition of virtual human and its representative virtual image has gradually caught the attention of the public.

关键词： realization Human surge

Mechanism of stall and surge in a centrifugal compressor with a variable vaned diffuser

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Chinese Journal of Aeronautics 2018年第6期31卷 1222-1231页

作者： Xiang XUE Tong WANG Tongtong ZHANG Bo YANG Gas Turbine Research Institute Shanghai Jiao Tong University

To expand the stable operating range of compressors, understanding the mechanism of flow instability at low flow rates is necessary. In this paper, the mechanism of stall and surge in a centrifugal compressor with a variable vaned diffuser is experimentally investigated, where the diffuser blade setting angle can be adjusted. Many dynamic pressure transducers are mounted on the casing surface of the compressor. From the design condition to surge, dynamic pressure data is recorded throughout the gradual process. According to the signal developing status, the typical modes of compressor instability are defined in detail, such as stall, mild surge, and deep surge. A relatively high-frequency stall wave originates in the impeller and propagates to the diffuser, and finally stimulates a deep surge in the compressor. The compressor behavior during surge differs at different diffuser vane angles. When the diffuser vane angle is adjusted, both the unstable form and the core factor affecting the overall machine stability change. A specific indicator is proposed to measure the instability of each component in a compressor, which can be used to determine the best region for stability extension technologies, such as a holed casing treatment, in different compressor applications.

关键词： Centrifugal compressor Flow instability Stall surge Vaned diffuser

A descriptive analysis of injury triage, surge of medical demand, and resource use in an university hospital after 8.12 Tianjin Port Explosion, China

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Chinese Journal of Traumatology 2015年第6期18卷 314-319页

作者： Guo-Qiang Li Shi-Ke Hou Xin Yu Xiang-Tao Meng Liang-Liang Liu Peng-BoYan Meng-Na Tian Shao-Lei Chen Hui-Juan Han Institute of Disaster and Emergency Rescue Medicine Pingjin Hospital Logistics College of The Chinese People's Armed Police Forces Tianjin 300162 China Department of Intensive Care Medicine Pingjin Hospital Logistics College of The Chinese People's Armed Police Forces Tianjin 300162 China contributed equally to this article as the co-firstauthor.

Objective： The 8.12 Tianjin Port Explosion in 2015 caused heavy casualties. Pingjin Hospital, an affiliated college hospital in Tianjin, China participated in the rescue activities. This study aims to analyze the emergency medical response to this event and share experience with trauma physicians to optimize the use of medical resource and reduce mortality of critical patients. Methods： As a trauma centre at the accident city, our hospital treated 298 patients. We retrospectively analyzed the data of emergency medical response, including injury triage, injury type, ICU patient flow, and medical resource use. Results： There were totally 165 deaths, 8 missing, and 797 non-fatal injuries in this explosion. Our hospital treated 298 casualties in two surges of medical demand. The first one appeared at 1 h after explosion when 147 wounded were received and the second one at 4 h when 31 seriously injured pa- tients were received, among whom 29 were transferred from Tianjin Emergency Center which was responsible for the scene injury triage. After reexamination and triage, only 11 cases were defined as critical ill patients, The over-triage rate reached as high as 62.07%. Seventeen patients underwent surgery and 17 patients were admitted to the intensive care unit, Conclusions： The present pre-hospital system is incomplete and may induce two surges of medical de- mand. The first one has a much larger number of casualties than predicted but the injury level is mild; while the second one has less wounded but almost all of them are critical patients. The over-triage rate is high. The hospital emergency response can be improved by an effective re-triage and implementation of a hosoital-wide damage control.

关键词： Mass casualty incident Over-triage surge of medical demand Damage control

surge Response of a Compliant Offshore Structure by Time Domain Simulation

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Journal of Shanghai Jiaotong university(Science) 2007年第6期12卷 838-844页

作者：王迎光薛雷平谭家华 School of Naval Architecture Ocean and Civil Eng. Shanghai Jiaotong Univ.

A single-degree-of-freedom equation of motion was used for modeling a compliant offshore structure exposed to viscous hydrodynamic loads. The equation of motion contains nonlinearities in the forms of both Duffing stiffness and Morison drag force with current. The water particle velocity and acceleration for calculating the Morison inertia and drag forces are modeled as Gaussian processes based on a Pierson-Moskowitz (P-M) elevation spectrum. The single-degree-of-freedom equation of motion containing different ocean current values are then numerically integrated via a fourth-order Runge-Kutta scheme. Time trajectories of the surge response displacements of the offshore structure and the response probability density curves are obtained. Furthermore, the ocean current influences on the response central moments up to the fourth order are studied. A literature review reveals that this is the first treatment of such a pair of nonlinearities in time domain. The simulation results are analyzed, and some conclusions valuable for engineering design are pointed out.

关键词： compliant offshore structure surge response Morison drag force P-M spectrum Monte Carlo simulation

Monitoring the 2008 cold surge and frozen disasters snowstorm in South China based on regional ATOVS data assimilation

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Science China Earth Sciences 2010年第8期53卷 1216-1228页

作者： DALE M.Barker National Center for Atmospheric Research BoulderColoradoUSA

In January 2008, South China experienced extremely low temperatures, heavy snowstorms, and severe frosts (2008 Frost Disaster, for short), which led to (partial) failures of observations from ground stations and ground radars resulting in a lack of necessary emergency information. To compensate for the failure of ground observations and to provide timely disaster information, the National Satellite Meteorological Center of China (NSMC) established a snow storm monitoring system for the 2008 Frost Disaster, which was based on the WRF Three Dimension Variational Assimilation and Forecast system (with NOAH as the land surface sub-process model) cooperatively developed by NSMC and the National Center for Atmospheric Research (NCAR), US. This system made full use of ATOVS and NCEP data to provide estimates of snow water equivalent every 6 hours during the storm. In this study, the ATOVS assimilation based snowstorm monitoring scheme was explored in detail, while the modeled results with and without ATOVS assimilation were compared against related observations. Results showed that the coupling of ATOVS assimilation into the proposed monitoring system evidently delineates weather characteristics of the snowstorm process more accurately, and demonstrated the feasibility of the system for snowstorm monitoring and forecasting. Through theoretical analyses and case discussion, this study proposes a reliable and practicable scheme to provide timely and accurate information on snow spatial distribution and temporal development for disaster mitigation, and illustrates a new application of ATOVS data.

关键词： 2008 cold surge and frozen disaster in South China ATOVS data assimilation snow depth snowstorm monitoring