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Global hydraulic stability analysis for dynamic regulation in multi-zone variable air volume air-conditioning system

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Energy and Built Environment 2024年第4期5卷 592-606页

作者： Tianyi Zhao Zhe li Xiuming li Honglian Peng institute of Building Energy School of Civil EngineeringFaculty of Infrastructure EngineeringDalian University of TechnologyDalian 116024China Anhui Province Key Laboratory of Intelligent Building&Building Energy Saving Anhui Jianzhu UniversityHefei 230022China School of Metallurgy Northeastern UniversityShenyang 110819China School of Architecture Harbin Institute of TechnologyHarbin150006China

Variable air volume air-conditioning system(VAV system)has multiple control loops that interfered with each other,which has serious impacts on its actual operation *** solve this problem,the index of global hydraulic stability,which takes the physical quantity of the pipe network pressure and the air flow rate as reference,is proposed based on Graph theory,and a pipe network model for the hydraulic calculation is ***,the simulation study based on the actual operation data is carried out in *** distribution of the pressure and the air flow in the pipe network is obtained,and the action interferences among adjacent terminal boxes are analyzed based on global hydraulic stability under damper position regulation strategy(DP strategy)and fan frequency regulation strategy(FF strategy).Results indicate that the FF strategy can decrease the total change distance of the damper position compared with the DP strategy,and then the fluctuation of the pressure and the air flow can be *** contribution of this study is to provide an evaluation index of global hydraulic stability,which can also be used in other air-conditioning systems with multiple terminals and multiple control loops.

关键词： VAV system Global hydraulic stability Adjustment strategy VAV box damper position

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土与混凝土结构接触面力学特性试验研究

水电能源科学 2009年第5期27卷 114-118页

作者：李登华郦能惠南京水利科学研究院岩土工程研究所江苏南京210024

使用新研制的土与结构接触面试验仪,较为系统地研究了土与混凝土板接触面的力学特性,分别从宏观和细观两方面量测和分析了接触区土体的应力变形性状及土与结构接触面的相互作用机理和规律。试验结果表明,接触面厚度约为7-8倍的平均粒径... 详细信息

使用新研制的土与结构接触面试验仪,较为系统地研究了土与混凝土板接触面的力学特性,分别从宏观和细观两方面量测和分析了接触区土体的应力变形性状及土与结构接触面的相互作用机理和规律。试验结果表明,接触面厚度约为7-8倍的平均粒径,达剪应力峰值后剪切位移主要发生于土与结构物接触表面,剪应力峰值、剪切位移和初始剪切劲度随法向应力的增大而增大,按混合法缩制的试料可降低试验缩尺效应影响,土颗粒级配、几何外形、物理力学特性和结构物表面几何外形和表面粗糙度均对接触面力学特性有较大影响。

关键词：接触面混凝土板力学特性试验

Mechanical characteristics and reservoir stimulation mechanisms of the Gulong shale oil reservoirs, the northern Songliao Basin

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Petroleum Science 2024年第3期21卷 2023-2036页

作者： Si-Wei Meng Jia-Ping Tao Tian-Jiao li Dong-Xu li Su-ling Wang liu Yang Xin liu li-Hao liang He liu PetroChina research institute of Petroleum Exploration Development Beijing100083China National Key Laboratory of Continental Shale Oil Daqing 163002HeilongjiangChina Dalian University of Technology Dalian116024LiaoningChina PetroChina Daqing Oilfield Co.Ltd. Daqing163002HeilongjiangChina Northeast Petroleum University Daqing163002HeilongjiangChina China University of Mining and Technology(Beijing) Beijing100083China

Shale oil of the Qingshankou Formation of the Gulong Sag,the northern Songliao Basin,represents the first attempt at large-scale development of pure-shale-type shale oil in *** integrating the multiscale refined reservoir characterization with macro-micro-scale mechanical testing,it is clarified that the Gulong shale is characterized by high clay mineral content,high rock plasticity,highly-developed bedding,and prominent mechanical anisotropy.A three-dimensional(3D)fracture propagation model of hydraulic fracturing was built for the Gulong shale,which fully captures the hydraulic fracture distribution pattern affected by the high bedding density,in-situ stress,and fracturing treatment *** research showed that due to influences of bedding,hydraulic fracturing in the Gulong shale forms a complex fracture morphology featuring the main fracture with multiple perpendicular branches that have different lengths(like the outdoor directional TV antenna);however,the vertical propagation of fractures is inhibited,and the fracture height is commonly less than 10 *** limited stimulated reservoir volume(SRV)is the main problem facing the fracturing stimulation of the Gulong shale *** density has vital effects on fracture morphology,so case-specific fracturing designs shall be developed for shale intervals with different bedding development *** reservoirs with welldeveloped bedding,it is suggested to properly increase the perforation cluster spacing and raise the volume and proportions of viscous fluids of the pad,so as to effectively promote vertical fracture propagation and improve reservoir stimulation *** study integrates multi-scale fine reservoir characterization and macro-micro-scale mechanical testing,as well as the construction and numerical simulation of hydraulic fracturing models for high-density layered shale reservoirs,providing a new approach and methodological framework for the fracturing research of high-density layer

关键词： Shale oil hydraulic fracturing High bedding density Fracture propagation model

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击实粘土压缩特性的试验研究

水利水运科学研究 1986年第3期 59-70页

作者：李雷南京水利科学研究院土工研究所

为了对非饱和击实粘土的压缩特性进行试验研究,研制了填土压缩仪,并用于横山坝心墙击实土的排水排气及不排水不排气条件下的压缩试验,研究了压缩变形的特性和孔隙水、气压力随竖向荷载的变化规律,还讨论了影响孔隙压力量测的主要因素及... 详细信息

为了对非饱和击实粘土的压缩特性进行试验研究,研制了填土压缩仪,并用于横山坝心墙击实土的排水排气及不排水不排气条件下的压缩试验,研究了压缩变形的特性和孔隙水、气压力随竖向荷载的变化规律,还讨论了影响孔隙压力量测的主要因素及其估算方法。

关键词：气压力平均误差测量误差粘土孔隙水压力传感器土方工程填土击实含水率含水量孔隙比陶土板试验研究压缩特性

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应用振动水冲法加固松砂坝壳的试验研究

水利水运科学研究 1982年第2期 40-51页

作者：郦能惠土工研究室

以往振动水冲法只是一种加固地基的方法。应用振动水冲法加固松砂壳坝是否会造成坝坡坍滑,是否会取得同样良好的效果,这些都是人们疑虑的问题。通过兴旺庄土坝振冲加固现场试验,我们发现:振冲时砂土振动加速度随着振源距增大而衰减,振... 详细信息

以往振动水冲法只是一种加固地基的方法。应用振动水冲法加固松砂壳坝是否会造成坝坡坍滑,是否会取得同样良好的效果,这些都是人们疑虑的问题。通过兴旺庄土坝振冲加固现场试验,我们发现:振冲时砂土振动加速度随着振源距增大而衰减,振冲时饱和砂土脉动孔隙水压力幅值随着振动加速度增大而增加,它们之间的关系都是幂函数关系。振冲时振冲器周围一米范围内的砂土发生液化而加密。液化的范围是有限的,因而振冲时砂土液化不会造成坝坡坍滑。现场试验还表明:振动水冲法用于加固松砂坝壳是成功的,可以把极松的砂加密到相对密度0.7以上。

关键词：振冲加固振冲法动孔隙水压力饱和砂土标准贯入试验动力触探加固地基振动水冲法加速度仪振冲器观测点振动液化相对密度比密度干容重干么重振冲加固试验灌砂法砂坝试验研究

Assessment of hydraulic performance changes of Dongting Lake after the Three Gorges Reservoir impoundment by a novel semi-empirical approach

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Journal of Geographical Sciences 2024年第8期34卷 1537-1557页

作者： SUN Zhaohua li Zhiqing CHEN li FAN Jiewei liU Ya State Key Laboratory of Water Resources engineering and Management Wuhan UniversityWuhan 430072China Yellow River Water&Hydropower Development Group Co. Ltd.Jiyuan 459017HenanChina Changjiang River Scientific research institute Wuhan 430010China

Floodplain lakes are important water storage areas in lowland regions that often undergo geomorphologic evolution,and timely topographic data are generally *** this study,to assess the impacts of lakebed deformation on hydraulic performance in Dongting Lake,a set of semi-empirical methods was proposed to establish performance graphs(PGs)using only hydrological *** methods were used to evaluate the changes in water level,storage capacity,and flood detention ability in Dongting Lake caused by topographic adjustment after the Three Gorges Reservoir *** methods showed that PGs can effectively simulate the water level and outflow processes of Dongting Lake with Nash-Sutcliffe efficiency coefficients(NSEs)above 0.9.A comparison of the estimated water level and discharge using PGs from different periods suggested that bed erosion in Dongting Lake caused water level decreases of 0.18 m and 0.32 m during the flood and dry seasons,*** the magnitude of erosion at high elevations in the lake is small,the impacts of bed adjustment on the storage capacity and flood detention ability are not currently *** study showed that the hydraulic performance of a floodplain lake can be evaluated independently of topographic data under the condition of no reverse flows or negative watersurface slopes.

关键词： Dongting Lake hydraulic performance graph bed adjustment semi-empirical approach backwater effect

Effect of inlet elbow on rotation stall in waterjet ppropulsionpump

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Fundamental research 2024年第4期4卷 898-906页

作者： Wei li Shuo li Leilei Ji Enda li Weidong Shi Ramesh Agarwal Muhammad Awais National research Center of Pumps Jiangsu UniversityZhenjiang 212013China institute of Fluid engineering Equipment Technology Jiangsu UniversityZhenjiang 212009China College of Mechanical engineering Nantong UniversityNantong 226019China departmentof Mechanical engineering&Materials Science Washington University in StLouisSt.LouisMO6330US.

To study the influence of an elbow inlet on the rotating stall characteristics of a waterjet propulsion pump(WJPP),a three-dimensional internal flow field in a WJPP under a straight-pipe inlet and elbow inlet is numerically *** comparing the hydraulic performance of WJPP under the two inlet conditions,the internal relationship between the inlet mode and the flow pattern in the pump is *** on unsteady pressure fluctuation characteristics and wavelet analysis,the influence of the inlet mode on the rotating stall is revealed,and the stall transient propagation characteristics under critical stall conditions are *** disturbance effects of the inlet channel geometry disappear under low flow rate conditions,the main disturbance is induced by the highspeed countercurrent,and the flow pattern under the elbow inlet is better than that under the straight-pipe *** the straight-pipe inlet,the single-stall nucleus in the WJPP temporarily experiences a low-frequency and high-amplitude disturbance,which subsequently transforms into a mode of multi-stall nuclei with high-frequency circumferential *** the elbow inlet,the rotating stall always maintains a mode of high-amplitude and low-frequency disturbance,which represents the transient characteristics of a single stall core propagating in the circumferential direction inside the *** results of this study have a reference value for structural design optimization in a WJPP.

关键词： Waterjet propulsion pump Inlet condition Rotation stall Flow structure Pressurefluctuation

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瀑布沟水电站大坝三维渗流数值模拟研究

水电站设计 1997年第1期13卷 29-38页

作者：段祥宝李祖贻南京水利科学研究院

应用有限单元法对大坝蓄水后的三维渗流场进行数值模拟研究，比较了各种渗控措施的效果，并提出了优化方案。提出了能迅速精确模拟厂房周围排水井列的新方法——附加渗径元法，首次对具体工程双道防渗墙局部损坏—开裂和开叉后渗流场的... 详细信息

应用有限单元法对大坝蓄水后的三维渗流场进行数值模拟研究，比较了各种渗控措施的效果，并提出了优化方案。提出了能迅速精确模拟厂房周围排水井列的新方法——附加渗径元法，首次对具体工程双道防渗墙局部损坏—开裂和开叉后渗流场的影响进行了分析。

关键词：心墙堆石坝渗流坝基有限元法水电站

research on the solid particle erosion wear of pipe steel for hydraulic fracturing based on experiments and numerical simulations

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Petroleum Science 2024年第4期21卷 2779-2792页

作者： Si-Qi Yang Jian-Chun Fan Ming-Tao liu De-Ning li Jun-liang li li-Hong Han Jian-Jun Wang Shang-Yu Yang Si-Wei Dai Lai-Bin Zhang State Key Laboratory of Oil and Gas Equipment CNPC Tubular Goods Research Institute Key Laboratory of Oil and Gas Safety and Emergency Technology China University of Petroleum Oil Production Technology research institute of liaohe Oilfield Company Tianjin Gas Storage Branch PetroChina Dagang Oilfield Company Petroleum Production engineering research institute Daqing Oilfield Company

Erosion wear is a common failure mode in the oil and gas industry. In the hydraulic fracturing, the fracturing pipes are not only in high-pressure working environment, but also suffer from the impact of the high-speed solid particles in the fracturing fluid. Beneath such complex conditions, the vulnerable components of the pipe system are prone to perforation or even burst accidents, which has become one of the most serious risks at the fracturing site. Unfortunately, it is not yet fully understood the erosion mechanism of pipe steel for hydraulic fracturing. Therefore, this article provides a detailed analysis of the erosion behavior of fracturing pipes under complex working conditions based on experiments and numerical simulations. Firstly, we conducted erosion experiments on AISI 4135 steel for fracturing pipes to investigate the erosion characteristics of the material. The effects of impact angle, flow velocity and applied stress on erosion wear were comprehensively considered. Then a particle impact dynamic model of erosion wear was developed based on the experimental parameters, and the evolution process of particle erosion under different impact angles, impact velocities and applied stress was analyzed. By combining the erosion characteristics, the micro-structure of the eroded area, and the micro-mechanics of erosion damage, the erosion mechanism of pipe steel under fracturing conditions was studied in detail for the first time. Under high-pressure operating conditions, it was demonstrated through experiments and numerical simulations that the size of the micro-defects in the eroded area increased as the applied stress increased, resulting in more severe erosion wear of fracturing pipes.

关键词： Erosion wear Applied stress Particle impact dynamics Erosion mechanism