Numerical simulation research on multi-electrodes resistivity imaging survey array
溶液喷射纺丝技术的基本原理及其纤维应用
(a )装置整体结构 (b )针头示意图图片来源:文献[1]。
图 1 溶液喷射纺丝法工艺流程根据研究,溶液喷射纺丝技术克服了熔喷纺丝技术只能加工热塑性聚合物以及静电纺丝生产效率低的缺陷,具有材料来源广泛、设备操作简单、安全风险低、纺丝效率高等优点。
近年来,有关该纺丝技术的研究逐渐成为热点,相关主题(包括基本原理相同的技术)的论文数量总体上呈增长态势(图始明显增长,这也在一定程度上印证了其在业内的受关加压气体注射泵压力表喷嘴接收距离接收网气流P P P 聚合物溶液气体/溶液边界空气/射流边界电阻会随间距的出现和扩展而逐渐增加,从而使电流减小。
而在释放应变的过程中,导电粒子因为改性膜的柔韧性可以重新连接,从而使得电阻恢复到原始阻值。
如图 6(b )所示,改性膜随着腕部不同程度的弯曲,电阻也发生了不同程度的改变,在肘部弯曲产生较大形变时,膜表面及内部的导电粒子间距增大,导电性能发生较明显变化,所以电阻变化更明显。
此外,在经过不同弯曲程度的重复弯曲运动时,也几乎能恢复初始电阻,说明改性膜有较好的弯曲重复性和稳定性。
3 结论(1)以丁二酸酐为中间体,可成功将类球形分子结 (a )人体手指弯曲 (b )人体腕部弯曲图 6 改性膜在人体不同部位不同弯曲程度和放松情况下的电阻变化率-时间变化情况时间/s 时间/s128400 5 10 15 20 25***********电阻变化率/%(a )直径为0.2 mm 的商业喷枪 (b )放置针的喷嘴注:图(a )来源于文献[3],图(b )来源于文献[4]。
图 3 不同的喷嘴807060504030201002012 2013 2014 2015 2016 2017 2018 2019 2020年份聚合物溶液储备器压缩气体入口溶液气体气体气体纳米纤维纤维(a)15 mg/mL (b)25 mg/mL (c) 50 mg/mL图片来源:文献[8]。
图 4 不同浓度PMMA溶液所纺纤维的SEM图像溶液流量、气压及接收距离等工艺参数对纳米纤维的形成也有影响。
4-安全工程科技英语标题的创作
(2) automatic sprinkler spray:自动水喷雾 系统
如何表到“起作用”
起作用: Wind plays a part in the fire spread 有相当大的作用:Wind has considerable impact/effect on the fire spread. 起核心主导作用:Sometimes wind plays a central and dominant role in the fire spread. 起主要(重要)作用:In general, wind plays a major/an important role in the fire spread. 起关键作用:Sometimes wind plays/has a key role in the fire spread.
(2) hazard: 危害;危害/ risk:包含概率的风险
e.g. hazard identification 危险源辨识 hazard / risk assessment 危害性/ 风险评估 risk characterization 风险表征(note: character, characteristics)
6. Effect of air velocity on pyrolysis of fire retardant coatings exposed to air heated at controlled temperatures
空气速度对暴露在加热至控制温度的空气中 的防火涂料热解的作用
Note: (1) air velocity:空气速度;较少用air speed (2) fire retardant coating 防火/阻燃涂料
低渗致密气藏压裂返排数值模拟研究
y〇1.37No.6 June. 2018石油化工应用PETROCHEMICAL INDUSTRY APPLICATION第37 6期2018 6 月油气工程低渗致密气藏压裂返排数值模拟研究王新杰$中国石化华北油气分公司勘探开发研究院,河南郑州450000)摘要:气井压裂返排情况直接影响着低渗致密气藏气井压后的产能和稳产时间。
考虑侵入区渗透率的损失、不同区域 相渗曲线的差异,同时考虑返排初期含水饱和度和地层压力的不均匀分布,应用局部网格加密、示踪剂追踪、饱和度分区等方法建立了压裂返排的气水两相黑油模型。
以示踪剂产量递减率定义了压裂返排结束的标志,研究了低渗致密气 藏压裂液的滞留机理,分析了裂缝导流能力和侵入区渗透率损失对气井稳产时间和初期阶段返排率的影响。
研究表明:平面上气体沿井眼处指进突破、侵入区高毛管力形成的渗吸效应、裂缝内部纵向上气椎的形成是造成低渗致密气藏压 裂液滞留的主要原因;裂缝导流能力在40 D.cm左右、侵入区渗透率损失系数在小于0.3时,既有利于压裂液的返排,同时又不会降低气井的稳产时间。
为制定压裂施工设计和指导压后产能评价工作提供了理论依据。
关键词:压裂返排;数值模拟;示踪剂;滞留机理中图分类号:TE377 文献标识码:A文章编号:1673-5285(2018)06-0003-06D01:10.3969/j.issn.1673-5285.2018.06.002Numerical simulation research on fracturing fluid flowbackin tight gas reservoirWANG Xinjie(Exploration and Development Research Institute of SINOPEC North China Oil andGas Company ,Zhengzhou Henan 450000, China)Abstract:Fracturing fluid flowback directly affects gas well production and stable production period. Considering permeability loss of invaded zone, the differences of relative permeability curve in different regions, uneven distribution of initial water saturation and formation pressure, the author establishes two phase black oil model about fracturing fluid flowback by using the technologies of local grid refinement, tracer tracking and saturation partition. Based on the criteria of tracer production decline rate, the author defines the mark of end of fracturing fluid flowback, studies the retention mechanism of fracturing fluid in tight gas reser-*收稿日期=2018-05-24基金项目:国家科技重大专项“低丰度致密低渗油气藏开发关键技术”,项目编号:2016ZX05048。
页岩气水平井段内多簇压裂暂堵技术的数值模拟研究及先导实验
基金项目 :中国石油天然气集团有限公司重大现场试验项目“深层页岩气有效开采关键技术攻关与试验——深层页岩气体积压裂技 术现场试验”(编号 :2019F-31-04)。
作者简介 :陈钊,1991 年生,助理工程师 ;主要从事非常规油气储层改造研究工作。地址 :(310023)浙江省杭州市余杭区五常街 道荆山湾路。E-mail: chenz85@
CHEN Zhao1, WANG Tianyi2, JIANG Xinchun2, YU Yue3, LU Haibing2, YI Xinbin2, JIANG Wei2, ZHAO Hong4
(1. PetroChina Zhejiang Oilfield Company, Hangzhou, Zhejiang 310023, China; 2. PetroChina Research Institute of Petroleum Exploration & Development, Langfang, Hebei 065007, China; 3. PetroChina Southwest Oil & Gasfield Company, Chengdu, Sichuan 610051, China; 4. PetroChina Liaohe Oilfield Company, Panjin, Liaoning 124010, China) Natural Gas Industry, Vol.41, SUPPLEMENTARY1, p.158-163, 3/25/2021. (ISSN 1000-0976; In Chinese) Abstract: Multi-cluster perforation technology in the horizontal hole section has become a new development direction of shale gas fracturing process, and temporary plugging and diverting technology is its effective auxiliary means, which can effectively improve the perforation opening efficiency. In order to provide technical support for optimizing the process parameters of shale-gas horizontal well fracturing, this paper optimized the related parameters of "5-cluster perforation in single stage and ball-sealer in-stage diversion" process through numerical stimulation. Then, the pilot test of "multi-cluster in single stage and temporary plugging and diverting" was carried out in Horizontal Well YS112HX-1 of Zhaotong National Shale Gas Demonstration Area. Finally, post-fracturing comprehensive evaluation was performed by using the technologies of micro-seismic monitoring, micro-deformation monitoring and pressure buildup test analysis. And the following research results were obtained. First, the balls shall be dropped the moment the injection volume of fracturing fluid reaches 900 m3, the number of balls shall be 1-1.2 times the number of perforations, and its diameter shall not be less than 13.5 mm. Second, micro-seismic, inclinometer and well test results are accordant. Compared with the conventional fracturing of 3-cluster perforation, the fracturing of 5-cluster perforation in single stage and ball-sealer in-stage diversion is better in fracture complexity. The matrix permeability in Well HX-1 is lower, but the permeability of the high-permeability area is much higher, so the stimulation effect is better. Third, according to the well test interpretation, the half fracture length in Well HX-1 is shorter than 100 m, which is deviated from the numerical simulation result. The well test result can be conversely used to optimize the numerical simulation parameters. Fourth, after the technology of "multi-cluster in single stage and temporary plugging and diverting" is applied in Well HX-1, the flow back presents the characteristics of early gas breakthrough, high wellhead pressure and high daily gas production. In conclusion, the research and test results are of guiding significance to the process parameter optimization of shale-gas horizontal well fracturing. Keywords: Shale gas; Multi-cluster in the single stage; Temporary plugging and diverting; Pilot test; Numerical simulation; Post-fracturing evaluation; Micro-seismic monitoring; Micro-deformation monitoring; Pressure buildup test analysis
RP-3 航空煤油燃烧特性及其反应机理构建综述
模型的建立,决定了燃烧室内燃料燃烧数值模拟的精 度和可靠性。国内外很多学者通过测量实际航空煤油 的物理和化学性质,确定模拟替代燃料的组分;通过 建立模拟替代燃料的化学反应动力学模型,对其进行 不同工况下的数值模拟;通过计算结果与实验结果的 比较,修订相应基元反应的系数,从而很好地表征其 燃烧特性。
国内外常用的航空 煤 油 主要 有 Jet A、Jet A-1、
MA Hong-an袁FU Shu-qing袁WU Zong-lin袁LIU Yu袁ZENG Wen 渊School of Aeroengine袁Shenyang Aerospace University袁Shenyang 110136袁China冤 Abstract: At present袁the numerical simulation calculation of the multi -step combustion reaction mechanism of coupled aviation kerosene had attracted the attention of scholars袁and the construction of the combustion reaction mechanism had become a research focus. The experimental rules on the selection of aviation kerosene surrogate fuel 袁the construction and simplification of chemical reaction kinetic model袁the ignition delay time and laminar burning velocity were introduced in detail. According to the research progress abroad 袁it was pointed out that the study of the combustion mechanism of domestic RP-3 aviation kerosene should start from the basic research and the related research should be carried out in a comprehensive 袁multi-dimensional and stereoscopic way in China in order to enrich the relevant research results and promote the high quality development of aeroengine. These research mainly included the establishment of the chemical kinetics model of domestic RP-3 aviation kerosene袁the basic experimental studies and the study of model combustor of aviation kerosene and simulated alternative fuels under the conditions of low temperature and high pressure. Key words: RP-3 aviation kerosene曰alternative fuel曰chemical reaction kinetic mechanism曰ignition delay time曰laminar burning velocity曰aeroengine
时延多智能体系统领导跟随一致性研究
引理 2[17] 对任意对称矩阵 Q Rnn 与任意向量 x R n ,可
T T T 得 min (Q) x x x Qx max (Q) x x 。
引理 3[18] 对任意向量 x, y R n ,实数 0 ,正定 Hermit 矩阵 H R nn , 存在不等式:xT Hy yT Hx xT Hx 1 yT Hy 。 引理 4 基于文献[14], 得到脉冲微分不等式(一类 Halanay 不等式的推广):
第 36 卷第 5 期 优先出版
计算机应用研究 Application Research of Computers
Vol. 36 No. 5 Online Publication
时延多智能体系统领导跟随一致性研究 *
张振华,彭世国
(广东工业大学 自动化学院, 广州 510006) 摘 要:为符合实际情形,针对不确定与随机发生非线性的多智能体系统,研究了有时延且网络拓扑切换时系统的领
导跟随一致性。传统协议通常保守的假设邻接个体间通信时延与个体和领导者间通信时延大小相同,新协议中上述时 延可以大小不同。相比于传统方法,新颖的将复杂网络同步问题研究领域对时延的处理方法引入到多智能体系统一致 性问题的研究中,利用一类推广的 Halanay 不等式,给出系统实现领导跟随一致性需满足的两个与时延无关的充分条 件, 即时延在相关参数满足定理条件的前提下不影响系统最终实现一致性。 相比其他方法得到的含有时延的判定条件, 本研究结果保守性更低,实例仿真验证了新协议的可行性。 关键词:脉冲控制;通信时延;多智能体系统;领导跟随一致性 中图分类号:TN915.04 doi: 10.3969/j.issn.1001-3695.2017.11.0789
建环专家简介
李先庭:主要研究方向主要从事室内空气环境数值模拟、应急通风、制冷系统与蓄能系统研究与开发。
在室内空气环境数值模拟方向,主要从事室内空气环境数值模拟方法、室内空气环境评价方法及应用研究。
数值模拟方法包括计算流体力学方法和区域模型方法,研究对象包括各种不同类型的风口和末端、各类热源和辐射、各种污染源的建模与计算,带回风的通风系统模拟等;室内空气环境评价方法包括送风有效性评价(如空气龄、换气效率等)、污染物排除有效性(如排空时间、排污效率、污染物年龄等)和热舒适三个方面,涉及稳态环境和动态环境;应用方向主要包括各种类型的高大空间(如体育场馆、候机大厅、剧场、中庭、厂房等)、洁净空间(如手术室、GMP车间、电子洁净厂房等)、运载工具(如车辆、舰船、飞机等)等。
在应急通风方向,主要研究有限时间条件下污染物的传播规律和应急通风系统的设计方法与运行控制,主要针对三种用途:(1)火灾防排烟;(2)公共场所有毒气体释放;(3)利用应急通风系统输送麻醉气体控制劫持现场,解救人质。
在制冷系统方向,主要从事小型制冷系统的模拟仿真与设备研究(包括各类房间空调器、汽车空调系统、舰船空调系统等)、制冷机组研究与开发。
研究内容包括制冷系统部件特性、系统优化匹配、运行与优化控制等。
在蓄能系统方向,主要进行冰蓄冷和水蓄冷系统的优化设计与控制研究,蓄冰槽的研究与开发,蓄冷蓄热水池/罐的设计与开发,以及土壤蓄能和季节性蓄冷系统的研究,食品冷藏运输研究等。
教学工作主要从事“室内空气流动数值模拟”、“暖通空调课程设计”、“人工环境学”等教学。
论文和论著参编普通高等教育“十五”国家级规划教材《建筑环境学》,申请或授权发明专利16项,发表科研论文百余篇,其中英文期刊40篇,国际会议篇28篇,中文期刊50篇.被SCI收录论文29篇,EI收录65篇。
部分代表性论文如下:1.Changqing Tian,Xianting Li,Chunpeng Dou. Experimental investigation and numericalsimulation on the adjustment dead zone of a variable displacement wobble plate compressor. International Journal of Refrigeration, v 28, n 7, Nov 2005, p 988-9962.Xianting Li, Zhen Yu,Bin Zhao, Ying Li. Numerical analysis of outdoor thermalenvironment around buildings. Building and Environment, v 40, n 6, June 2005, p 853-8663.Xianting Li, Jianrong Yang, Wei Sun. Strategy to optimise building ventilation toaid rescue of hostages held by terrorists. Indoor and Built Environment, v 14, n 1, 2005, p 39-504.Xianting Li, Bin Zhao.Accessibility: a new concept to evaluate the ventilationperformance in a finite period of time. Indoor and Built Environment, v 13, n 4, Aug 2004, p 287-2935.Dongning Li, Xianting Li, Yunzhi Guo, Jianrong Yang, Xudong Yang. Generalizedalgorithm for simulating contaminant distribution in complex ventilation systems with recirculation. Numerical Heat Transfer Part A-Applications,v 45, n 6, April 2004, p 583-5996.Jianrong Yang, Xianting Li, Bin Zhao. Prediction of transient contaminant dispersionand ventilation performance using the concept of accessibility.Energy and Buildings, v 36, n 3, March 2004, p 293-2997.Xianting Li, Dongning Li, Xudong Yang, Jianrong Yang. Total air age: An extensionof the air age concept. Building and Environment, v 38, n 11, Nov 2003, p 1263-1269 8.Bin Zhao, Xianting Li, Dongning Li, Jianrong Yang. Revised air-exchange efficiencyconsidering occupant distribution in ventilated rooms. Journal of the Air and Waste Management Association, v 53, n 6, Jun 2003, p 759-7637.荣誉、奖励及参加学术团体的情况获省部级科技进步奖2项(北京市科学技术进步三等奖,2001年;教育部科技进步成果二等奖,2000年),现为北京制冷学会副理事长,国际制冷学会E2专业委员会委员,中国制冷学会第五专业委员会委员,全国暖通空调及净化设备标准化技术委员会委员,《建筑热能通风空调》、《制冷与空调》和《制冷空调与电力机械》编审委员会委员,ASHRAE(美国供热、通风、制冷与空调工程师学会)会员、中国制冷学会高级会员朱颖心:主要研究方向主要研究领域与项目1.可持续建筑研究(1)科技部国家“十五”攻关项目:绿色建筑关键技术研究课题一:绿色建筑的规划设计导则和评估体系研究课题五:降低建筑物能耗的综合关键技术研究(2)科技部奥运科技十大专项课题:绿色奥运建筑评估体系;(3)北京市科委项目:新建建筑能耗评估体系与超低能耗示范建筑的建立与实践研究;(4)国家自然科学基金重点项目:住区微气候的热物理问题。
车门开度对关门时车内人耳位置峰值压力的影响
10.16638/ki.1671-7988.2021.05.037车门开度对关门时车内人耳位置峰值压力的影响苏瑞,李晶,于潮,张贺林(中国汽车技术研究中心有限公司,天津300399)摘要:为了进一步探究关门压耳感的影响因素,进而解决目前车门关闭时车内压力过大的问题。
利用计算流体力学软件Star-ccm+的重叠网格技术分析关门时不同车门开度对车内峰值压力的影响。
将不同车门开度的瞬时速度作为仿真计算的输入,得到该车型关门耳压计算值,并通过试验测试相同状态下实际关门耳压。
仿真结果与测试结果对比显示车门开度35°与70°状态下得到的关门耳压基本一致,车门开度对关门时车内峰值耳压影响较小。
在以后的测试和仿真模拟过程中可以快速提高仿真研究的进度和工作效率。
关键词:压耳感;峰值压力;车门开度;重叠网格;瞬时速度中图分类号:U467 文献标识码:A 文章编号:1671-7988(2021)05-129-05Effect of Door Opening on Peak Pressure of Ear Position in the Car When ClosingSu Rui, Li Jing, Yu Chao, Zhang Helin(China Automotive Technology & Research Center Co., Ltd., Tianjin 300399)Abstract: In order to further explore the influencing factors of the sense of pressure when closing the door, and then solve the problem of excessive pressure in the car when the door is closed. The effect of different door openings on the peak pressure in the car when closing the door was analyzed using the overlapping grid technology of the computational fluid dynamics software Star-ccm+. The instantaneous speed of different door openings is used as the input of the simulation calculation to obtain the calculated door closing ear pressure value, and the actual door closing ear pressure is tested through the test. The comparison between the simulation results and the test results shows that the door opening ear pressures obtained in the state of the door openings of 35° and 70° are basically the same, and the door opening degree has little effect on the peak ear pressure in the vehicle when the door is closed. In the future testing and simulation process, the progress and efficiency of simulation research can be quickly improved.Keywords: Ear pressure; Peak pressure; Door opening; Overset mesh; Instantaneous speedCLC NO.: U467 Document Code: A Article ID: 1671-7988(2021)05-129-051 前言关门耳压感是目前车型普遍存在的问题。
基于电荷等效法的电容短路放电微观特性数值模拟研究
Abstract In order to study the microscopic characteristics of the capacitive circuit short-circuit discharge based on the IEC spark test device, this paper established a two-dimensional parallel plate simulation model with tungsten as the anode material and cadmium as the cathode material. The simulation area was filled with air and the concentration was 8.5%. According to the principle of charge equivalence, the model adopts the particle method (PIC/MCC) to carry out numerical simulation research. The effect of the voltage between the electrodes, the distance between the electrodes and the external capacitor on the short-circuit discharge process of the capacitor is analyzed. Changes in voltage, current, various particle concentrations, and average electron energy during the discharge process after breakdown. The simulation results show that with the increase of the voltage between electrodes, the average electron energy also gradually increases. The influence of the voltage between electrodes on the ionization of N2 is much greater than that on O2 and CH4; when the electrode spacing becomes larger, the breakdown needs the longer the time, the more difficult it is for the gas medium
催泪弹非致命效能分析计算
催泪弹非致命效能分析计算王志刚;郭三学【摘要】催泪弹是驱散群体性目标最有效的一种非致命防暴弹,特别是爆炸式催泪弹,刺激剂可瞬间释放,能快速作用于有生目标.但在实际战术运用中,催泪弹的非致命效能没有具体的衡量指标,导致其使用没有科学依据.根据爆炸式催泪弹气溶胶烟雾扩散特征,应用重气和非重气扩散数学模型,通过计算虚源点,将两种模型有效结合起来,对气溶胶烟雾扩散过程进行分析研究,得到气溶胶烟雾扩散半径和浓度变化规律,分析计算了单枚催泪弹有效作用区域,以此作为催泪弹非致命效能的衡量指标.研究结果表明,在风速为2 m/s时,39 s后单枚催泪弹的有效扩散面积可达602.1 m2,且烟雾浓度不低于1 mg/m3,计算结果与试验结果基本符合.【期刊名称】《兵工学报》【年(卷),期】2017(038)001【总页数】5页(P59-63)【关键词】兵器科学与技术;催泪弹;非致命效能;分析计算【作者】王志刚;郭三学【作者单位】武警工程大学装备工程学院,陕西西安710086;武警工程大学装备工程学院,陕西西安710086【正文语种】中文【中图分类】TJ416催泪弹是驱散群体性目标最有效的一种非致命防暴弹。
它以燃烧或爆炸的方式(本文研究的是爆炸式催泪弹),将装填在弹体内的刺激剂装药释放出来,并形成气溶胶烟雾,刺激有生目标的眼睛、皮肤及上呼吸道等器官,使其短时间失去抵抗能力。
目前,在催泪弹非致命效能研究方面,未查到国外相关文献报道。
国内方面,郭三学等[1]对爆炸式催泪弹的安全性和可靠性设计进行了研究,对弹体零件强度、爆炸冲击波、破片及残骸杀伤性进行了理论分析和计算;朱文坤等[2]提出了对爆炸式催泪弹非致命效应评价的方法,将数学模型应用到非致命效应的效能评估中,对爆炸式催泪弹的非致命效应进行了综合评估;张振中[3]以粒子的光散射理论为基础,研究了催泪弹烟幕粒子粒径浓度的测量方法,对催泪弹的非致命效应给出了定量评估。
上述文献均未对催泪弹气溶胶烟雾扩散进行分析研究,未能对催泪弹的非致命效能给出一个具体的衡量指标,这导致在实际处置群体性事件时,催泪弹的投掷数量没有科学依据。
压气机钛合金叶片外物损伤规律数值仿真研究
压气机叶片外物冲击损伤过程进行数值仿真ꎬ开展部分工况下外物损伤试验并进行对比ꎬ以验
证仿真模型的准确性ꎮ 结果表明:数值仿真计算得到的损伤尺寸以及形貌与试验数据吻合良
好ꎮ 外物材料类型对冲击损伤影响十分明显ꎬ材料密度及硬度越大ꎬ损伤宽度与深度越大ꎻ高
Foreign object damage tests under some working conditions were implemented and compared to verify the accuracy of the simulation
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speed. The impact angle has less influence on the damage size.
Keywords: compressor bladeꎻ titanium alloyꎻ foreign object damageꎻ finite elementꎻ numerical simulation
进一步服务于疲劳性能的影响研究ꎮ 而在数值仿真方面ꎬ
诸多学者 通 过 LS - DYNA、 DYTRAN、 ABAQUS 等 商 用 软
件ꎬ采用 Bammann 和 Johnson-Cook 等材料模型ꎬ模拟了多
第一作者简介:刘保果(1977—) ꎬ男ꎬ河南新野人ꎬ工程师ꎬ研究方向为船舶建造与监管技术ꎮ
信息技术
刘保果ꎬ等压气机钛合金叶片外物损伤规律数值仿真研究
DOI:10.19344 / j.cnki.issn1671-5276.2022.01.034
压气机钛合金叶片外物损伤规律数值仿真研究
基于CFD技术的螺旋桨非定常流场数值模拟
基于CFD技术的螺旋桨非定常流场数值模拟高飞飞【摘要】针对单独螺旋桨模型,基于动态结构网格搭接技术,采用CFD方法对其非定常流场进行了数值模拟.首先针对全部外形生成多块点搭接和面搭接两套计算网格,通过分析两套网格的计算结果,验证动态网格搭接技术的可行性和正确性,得出螺旋桨性能参数随转速的变化规律.在此基础上分析了雷诺平均NS(RANS)方程和Euler方程的数值模拟结果.最后研究了攻角对单独螺旋桨性能参数的影响.研究结果表明:动态网格搭接技术能够很好地模拟非定常螺旋桨的性能参数.螺旋桨的拉力系数和功率系数都随着转速的增加而增大.对螺旋桨非定常流场进行数值模拟时,采用Euler方程就能够满足工程精度的需求.攻角0度时单片桨叶的拉力系数和转矩系数都是恒值,而在攻角10度时却都呈现出周期性的正弦曲线.%CFD technology was applied to do the numerical simulation of unsteady flow around the single propeller model, which was based on the structured dynamic grids. To start with, two sets of calculation grids consisting of multi-block point-to-point and face-to-face patched grid were created in terms of the whole shape. Then through the contrastive analysis of the computational results, the feasibility and accuracy of dynamic patched grids were verified. At the same time, the regular patterns in which propeller performance parameters varied in accordance with the rotation rate were obtained. Numerical simulation results of Reynolds-Averaged Navier-Stokes (RANS) equations and Euler equations were analyzed based on the research above. In the end, made a study of the influence of angles. The results show that dynamic patched grids are efficient to simulate the characteristicparameters of the unsteady flow. The thrust and power cofficients increase considerably with the rise of the rotational speeds. Euler equations are qualified for engineering precision requirement in the numerical simulation of unsteady flow around single propeller. The thrust and torque cofficients are contant when the angle is 0 degree and take on sinusoidal vibration when 10 degree.【期刊名称】《科学技术与工程》【年(卷),期】2011(011)030【总页数】6页(P7564-7569)【关键词】螺旋桨;动态网格搭接;Navier-Stokes方程;Euler方程;非定常方法【作者】高飞飞【作者单位】西安航空计算技术研究所,气动数值模拟航空科技重点实验室,西安710068【正文语种】中文【中图分类】V211.3虽然航空推进技术早已进入喷气时代,但在航空发展史上起着重要作用并产生拉力的气动部件——螺旋桨并没有退出航空领域。
混凝土塑性—损伤本构模型研究
混凝土塑性—损伤本构模型研究一、本文概述Overview of this article混凝土作为一种广泛应用的建筑材料,其力学性能和损伤行为的研究一直是土木工程领域的重要课题。
本文旨在深入研究和探讨混凝土塑性-损伤本构模型,该模型能够更准确地描述混凝土在复杂应力状态下的力学响应和损伤演化过程。
通过对混凝土塑性-损伤本构模型的研究,不仅有助于我们更好地理解混凝土的力学特性,还能为混凝土结构的设计、分析和优化提供理论基础和技术支持。
As a widely used building material, the study of mechanical properties and damage behavior of concrete has always been an important topic in the field of civil engineering. This article aims to conduct in-depth research and exploration on the plastic damage constitutive model of concrete, which can more accurately describe the mechanical response and damage evolution process of concrete under complex stress states. The study of the plastic damage constitutive model of concrete not only helps us better understand the mechanical properties ofconcrete, but also provides theoretical basis and technical support for the design, analysis, and optimization of concrete structures.本文首先介绍了混凝土塑性-损伤本构模型的基本概念和理论框架,包括塑性理论、损伤力学以及混凝土材料的特殊性质。
考虑惯容的颗粒阻尼器等效力学模型及其受控结构稳态解研究
文章编号:1000-4750(2021)04-0136-14考虑惯容的颗粒阻尼器等效力学模型及其受控结构稳态解研究黄绪宏,许维炳,王 瑾,闫维明,陈彦江(北京工业大学工程抗震与结构诊治北京市重点试验室,北京 100124)摘 要:颗粒阻尼技术因减振效果好、作用频带宽等优点使其在土木工程领域中具有良好的应用前景,然而因其具有高度复杂的非线性力学特性,并缺少合理的力学模型,限制了其在实际工程中的应用和发展。
鉴于此,以土木工程应用为背景,在不考虑阻尼颗粒发生堆积的前提下,通过引入惯容器来考虑颗粒群滚动对阻尼器减振机理及减振效果影响,建立了考虑惯容的多颗粒阻尼器等效单颗粒力学模型;结合颗粒运动状态,分别进行了未碰撞时及碰撞发生后多颗粒阻尼器单自由度结构的响应分析,重点探讨了惯容系数对未碰撞时动力放大系数频响曲线及碰撞发生后周期2次碰撞稳态解析解的影响规律,并采用数值仿真和试验方法进行验证。
结果表明,考虑惯容属性后等效模型能够进一步明晰多颗粒阻尼器由于颗粒群滚动引起的非线性特性,惯容系数对多颗粒阻尼器未碰撞时动力放大系数频响曲线及碰撞后周期运动解析解存在的边界条件及稳定性具有显著影响。
进行的周期2次碰撞理论解析为颗粒阻尼器进一步参数影响分析及减振机理分析提供理论基础。
关键词:多颗粒阻尼器;等效模型;惯容;周期运动;稳定性中图分类号:TU352.1+1 文献标志码:A doi: 10.6052/j.issn.1000-4750.2020.06.0359EQUIVALENT MODEL OF MULTI-PARTICLE DAMPER CONSIDERINGINERTER AND STEADY-STATE SOLUTION OFCONTROLLED STRUCTUREHUANG Xu-hong , XU Wei-bing , WANG Jin , YAN Wei-ming , CHEN Yan-jiang(Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit, Beijing University of Technology, Beijing 100024, China)Abstract: Multi-particle dampers have a good application prospect in the field of civil engineering structures because of their good damping efficiency and wide frequency band. However, the highly complex nonlinear mechanical properties and the lack of a reasonable mechanical model limit its application and development in practical engineering. In view of this, an equivalent single-particle mechanical model with inerter was established without considering the accumulation of particles. The introduction of inerter further considered the influence of particle rolling on the damping mechanism and effect. Then, the theoretical analysis of a single-degree-of-freedom structure with a multi-particle damper was carried out. The influence of inertance on the frequency response curve of displacement in the non-collision stage and the steady-state analytical solution of periodic collision after collision were analyzed emphatically. Numerical simulation and experimental research were also carried out to verify the correctness of the theoretical analysis. The results show that the equivalent model proposed can further clarify the nonlinear characteristics of the multi-particle damper after considering the inerter. The inertia收稿日期:2020-06-07;修改日期:2020-10-29基金项目:国家自然科学基金项目(51978021,51908015);国家重点研发计划项目(2017YFC1500604,2017YFC1500603)通讯作者:王 瑾(1987−),女,河北人,博士后,主要从事结构减震与振动控制研究(E-mail: ******************).作者简介:黄绪宏(1993−),男,山东人,博士生,主要从事结构振动控制研究(E-mail: ***************);许维炳(1986−),男,安徽人,副研究员,博士,主要从事桥梁结构抗震减震研究(E-mail: *****************.cn );闫维明(1960−2020),男,黑龙江人,教授,博士,主要从事结构隔震、减震与振动控制研究(E-mail: **************.cn );陈彦江(1963−),男,黑龙江人,教授,博士,主要从事桥梁抗震减震、桥梁稳定与振动等方面的研究(E-mail: ***************).第 38 卷第 4 期Vol.38 No.4工 程 力 学2021年4 月Apr.2021ENGINEERING MECHANICS136coefficient has a significant influence on the frequency response curve of the controlled structure in the non-collision stage and the analytical solution (boundary and stability) of the periodic motion after collision. The steady-state analytical solution of periodic motion provides a theoretical basis for further parameter influence analysis and for damping mechanism analysis of particle dampers.Key words: multi-particle damper; equivalent model; inerter; periodic motion; stability颗粒阻尼器最早由冲击减振器发展而来,用于涡轮机叶片的减振研究中[1],然而由于单颗粒冲击阻尼器在减振过程中会产生较大的噪声及其对设计参数的敏感性限制了其在实际中的应用。
基于机器学习的双椭圆柱绕流场预测
基于机器学习的双椭圆柱绕流场预测作者:周彦澄奚喆霍韵羽来源:《中国新通信》2022年第03期【摘要】雙椭圆柱绕流是一种典型的钝体绕流现象,本文针对并列双椭圆柱二维绕流问题提出了一种基于机器学习方法的智能预测模型。
首先通过本征正交分解(POD)将原始高维流场信息降阶为低维空间内的一组流场特征系数向量,然后采用门控循环单元(GRU)神经网络模型构建当前时刻特征系数与之前若干时刻特征系数之间的时序关系,最后以初始若干时刻的流场特征系数为输入,利用训练获得的模型预测后续时刻的特征系数并重构全阶流场信息。
涡量场预测结果表明,本文构建的预测模型能够有效地捕捉双椭圆柱绕流场的周期性规律,能在较长的时间跨度内保持与CFD模拟相当的流场预测精度,且具有更高的预测效率。
【关键词】双椭圆柱绕流本征正交分解 GRU神经网络流场预测引言:单个或多个钝体的绕流现象广泛存在于航空、建筑、能源、环境等领域,对不同形状和数量的钝体绕流现象开展研究具有重要的工程意义。
同时,钝体绕流也是流体力学中的经典问题之一,受到学术界的广泛关注。
随着数值计算方法的发展,人们研究的钝体从最经典的单圆柱体[1]发展到双圆柱体[2]、多圆柱体[3]、椭圆柱体[4]、双椭圆柱体[5]等,所呈现的流动现象也越来越丰富。
尽管传统计算流体力学(CFD)方法是解决科学和工程问题的重要工具,但开展复杂流动系统的高精度数值模拟通常需要耗费大量的计算资源。
近年来,机器学习方法在图像识别、语言翻译、工程科学等领域展现出了巨大的潜力,通过结合机器学习方法构建降阶模型用于复杂流场的重构和预测不仅可以保证足够的精度,同时也可以节省大量的计算资源,因此成了近来流体力学研究的一个热点。
机器学习方法善于从大量数据中发掘潜在的模式和规律,也善于描述数据间复杂的非线性关系。
机器学习方法的上述特点使其非常适用于描述像钝体绕流这样的与时间相关的复杂非线性流动问题。
在最近的研究中,人们通过本征正交分解(POD)、自编码器等降阶方法与长短期记忆(LSTM)循环神经网络[6]、时间卷积神经网络(CNN)[7]的结合,用于二维圆柱绕流场的预测。
多光束激光选区熔化拼接区域熔池动力学行为数值模拟
表面技术第52卷第11期多光束激光选区熔化拼接区域熔池动力学行为数值模拟李泓历1a,傅广1a,1b*,任治好2,李舒玥1a,彭庆国1a,肖华强1a,李少波1b(1.贵州大学 a.机械工程学院 b.省部共建公共大数据国家实验室,贵阳 550025;2.重庆大学 机械工程学院,重庆400044)摘要:目的针对多光束激光选区熔化加工拼接重叠区域的质量控制难题,研究拼接重叠区域的缺陷形成机理与控制手段。
方法通过建立激光选区熔化介观尺度高保真数值模型,基于流体体积法和射线追踪热源,还原粉末熔化凝固的加工过程,研究不同加工参数下拼接重叠区域熔池动力学和激光反射吸收行为,并对比分析拼接重叠区域和非拼接重叠区域激光-材料能量耦合机制。
结果在拼接重叠区域大小不同的情况下,重叠区域长度分别为160、200、240 μm时,其拼接重叠区域熔道宽度宽于非拼接重叠区域,拼接重叠区域与非拼接重叠区域存在高度差,且重叠区域的全局激光吸收率要高于非重叠区域,其中重叠区域皆有孔隙缺陷,重叠区域240 μm长度方案下的全局平均吸收率达到最高(0.417 56)。
在拼接重叠区域长度为240 μm、扫描速度为0.9 m/s和1.2 m/s时,由于获得的能量低于扫描速度为0.6 m/s时的能量,其重叠区域不存在孔隙缺陷。
结论拼接重叠区域的表面形貌和孔隙缺陷与熔池动力学和激光反射吸收行为密切相关,合适的加工参数可以改善拼接重叠区域的成形质量。
关键词:激光选区熔化;数值模拟;重叠区域;激光吸收;熔池演变中图分类号:TG665 文献标识码:A 文章编号:1001-3660(2023)11-0406-13DOI:10.16490/ki.issn.1001-3660.2023.11.035Numerical Simulation of Molten Pool Dynamics inMulti-beam Laser Selective Fusion Splicing RegionLI Hong-li1a, FU Guang1a,1b*, REN Zhi-hao2, LI Shu-yue1a,PENG Qing-guo1a, XIAO Hua-qiang1a, LI Shao-bo1a(1. a. School of Mechanical Engineering, b. State Key Laboratory of Public Big Data, Guizhou University Guiyang 550025,China; 2. College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China) ABSTRACT: The quality control problem of the stitching overlap area of multi-beam selective laser melting processing was收稿日期:2022-09-12;修订日期:2023-03-02Received:2022-09-12;Revised:2023-03-02基金项目:贵州省科学技术基金项目[黔科合基础-ZK(2021)一般268];国家自然科学基金(52065009);国家重点研发计划(2020YFB1713300);贵州大学引进人才科研项目(贵大人基合字[2021]87)Fund:National Science and Technology Foundation of Guizhou Province [ZK(2021)268]; The National Natural Science Foundation of China (52065009); National Key Research and Development Program (2020YFB1713300); Guizhou University Talent Introduction Research Project ([2021]87)引文格式:李泓历, 傅广, 任治好, 等. 多光束激光选区熔化拼接区域熔池动力学行为数值模拟[J]. 表面技术, 2023, 52(11): 406-418.LI Hong-li, FU Guang, REN Zhi-hao, et al. Numerical Simulation of Molten Pool Dynamics in Multi-beam Laser Selective Fusion Splicing Region[J]. Surface Technology, 2023, 52(11): 406-418.*通信作者(Corresponding author)第52卷第11期李泓历,等:多光束激光选区熔化拼接区域熔池动力学行为数值模拟·407·studied to investigate the defect formation mechanism and control means of the stitching overlap area. Due to the difficult observation of the interaction behavior between laser and material during selective laser melting, based on the volume of fluid method and ray-traced heat source, the process of powder melting and solidification was restored by establishing a high-fidelity numerical model of selective laser melting at mesoscopic scale to study the melt pool dynamics and laser reflection & absorption behaviors in the spliced overlap region under different processing parameters, and to compare and analyze the laser-material energy coupling mechanism in the spliced overlap region and the non-spliced overlap region, to explore means of suppressing defects in overlapping regions of splicing. The numerical simulation model was based on computational fluid dynamics theory and a multiphase flow model with the finite volume method was used and combined with physical field models such as melting and solidification, heat loss, surface tension, recoil pressure, and ray tracing heat source. A single-pass numerical simulation of laser-selected melting was performed at a laser power of 430 W, in which there was no interruption time between the two laser beams, and the second beam was processed immediately after the completion of the first beam, and the two beam scans were of equal length. The two beams were in one scanning path, and the starting point of the second beam scan was before the end point of the first scan, resulting in a stitching overlap region. Numerical simulations were performed at the same stitching overlap area scan speed, different stitching overlap area size and the same stitching overlap area size, different stitching overlap area scan speed, where the non-stitching overlap area scan speed in both cases was 0.6 m/s. With different sizes of spliced overlap regions, the spliced overlap regions had wider fusion channel width than the non-spliced overlap regions when the length of the overlap regions was 160 μm, 200 μm and 240 μm, respectively. There was a height difference between the spliced overlap regions and the non-spliced overlap regions, and the global laser absorption rate of the overlap regions was higher than that of the non-overlap regions, where the overlap regions all had porosity defects, and the highest global average absorption rate was0.417 56 for the 240 μm overlap region. The highest global average absorption rate was 0.417 56 for the 240 μm length of theoverlapped area. The energy obtained was lower than that obtained at the scanning speed of 0.9 m/s and 1.2 m/s for the 240 μm length of the overlapped area. There were no porosity defects in the overlapped area. By analyzing the results of numerical simulations and experimental situations studied by other scholars, the surface morphology and porosity defects of the splice overlap region are closely related to the melt pool dynamics and laser reflection and absorption behaviors. Suitable processing parameters can improve the forming quality of the splice overlap region. This research can provide a reference for multi-beam laser selective melting and splicing overlap area forming.KEY WORDS: selective laser melting; numerical simulation; overlap region; laser absorption; molten pool evolution激光选区熔化(Selective Laser Melting,SLM)是一种主流且有发展前景的增材制造技术[1]。
微通道内单相及气液两相流动换热数值模拟研究进展综述
0 引言
微通道换热器的工程背景来源于 20世纪 80 年代高密度电子器件的冷却和 20世纪 90年代出 现的微电子机械系统的传热问题。随着能源问题 的日渐突显,各国的经济发展与微小器件的发展 息息相关,换热设备在满足热交换要求的前提下, 需要向缩小体积的方向优化,以节约更多空间和 能源[1]。随着微型换热设备的出现和普及,微尺 度传热问题也成为换热器试验和数值模拟研究的 重点。Tuckerman等[2]提出了如图 1所示的微通 道换热器,通过多个细微通道内的介质流动带走 电子芯片积聚的热量,成功地解决了随着科技发 展、芯片集成度越来越高带来的高热流密度散热 问题。孙淑风等[3]研究了液氮在尺寸为 0.55~ 1.5mm的微通道中流动沸腾的传热效果,发现狭 窄通道的强制对流沸腾换热对沸腾换热具有强化 作用,其中,液氮在狭窄通道形状为弦月型的传热 系数是常规尺寸管道的 3~5倍,随着狭窄的间隙 尺寸的减少,换热系数也得到提高。综上所述,微 通道换热因其体积小、换热效率高、耐压性能强等 特点被认为是最有发展前景的高热流密度散热技 术之一。
焊接中英文翻译例句
焊接阅读英汉对照1heat input热输入Improvement of HAZ Toughness in High Strength Steels under High Heat Input采用细小贝氏体改进大线能量高强度钢板的热影响区(HAZ)韧性Effect of heat input on structure and mechanical properties of welded joint in a SOOMPa grade RFC steel热输入对800MPa级钢接头组织及性能的影响Microstructure of large heat input welding steels with low susceptivity to weld cracking大线能量低焊接裂纹敏感性钢的显微组织Development of fire-resistant and weathering construction steel weldable with high heat input and its typical use大线能量焊接耐火耐候建筑用钢的研制及应用Effects of heat input on mechanical and corrosion properties of du-plex stainless steel tubular welded joint热输入对双相不锈钢管接头力学和腐蚀性能的影响After strain ageing a significant loss of the fusion line toughness would happen. The loss is basically because of the welding heat effect, the pre-tensile deformation and ageing.( 1 )Among the total loss, pre-tensile deformation caused the largest amount loss, approximately 50%.( 2 )The loss caused by welding heat effect is closely related to the heat input. Both too high or too low cause loss. There is a optimum heat input that causes the least loss熔合线在变形时效以后韧性要发生很大折损,韧性主要折损在以下几方面:焊接热影响;预拉伸变形;人工时效等。
近年主要成果-上海交通大学
1.承担项目情况:1)国家自然基金项目,“辊弯成形全流程动态模拟技术研究”,编号:50375095, 经费:24万元,起止年月:2004.1~2006.12,负责人。
2)国家自然基金重点项目,“材料智能化近终成形加工技术的若干基础问题”,编号:50634010, 经费:180万元,起止年月:2007.01~2010.12,主要参加人。
3)国家973计划前期研究项目“材料制备新方法探索及性能研究”,编号:2006CB708600,总经费:1094万元,起止年月:2006.12~2008.11,负责人。
4)国家863计划重点项目,“高强高韧镁合金及其应用技术研究”,编号:002AA331120,经费:340万元,起止年月:2002.6~2005.6,负责人。
5)国防科工委民口配套项目,“XXX轴承的研究”,编号:MKPT-05-268,经费:165万元,起止年月:2005.1~2006.12,负责人。
6)上海市重大基础研究项目“成形制造中材料微观结构与应力场控制”,编号:06dj14005, 经费:500万元,起止年月:2007.01~2010.12,主要参加人。
7)上海市重点基础研究项目,“镁合金板材变形机理及温热冲压成形性能研究”,编号:03JC14045,经费:30万元,项目起止年月:2003.12~2006.12,负责人。
8)教育部高等学校博士点专项科研基金,“基于细观织构演化的金属板材成形性能理论研究”,编号:20030248029。
经费:5万元,起止年月:2004.1~2006.12,负责人。
9)宝钢股份有限公司委托项目“ERW高频直缝焊管排辊成形工艺数字化平台技术研究”,经费:110万元,起止年月:2006.12~2008.4,负责人。
10)美国福特汽车公司University Research Project (URP)项目“Integrated Computational Materials Engineering (ICME) Methodology Development forAlloy Design & Defects Control for Al & Mg Extrusions”, 经费:12万美元,起止年月:2007.1~2009.12,负责人。
基于ProE 5.0的圆柱凸轮多种建模方法 及其多轴仿真加工研究
根据圆周长公式:C=π*D (1)计算得出该圆柱体外圆柱的周长为100πmm ,由于圆柱体高度尺寸为100mm ,因此展开平面图中的矩形尺寸应为100πmm×100mm 。
根据展平面开图中所标注的尺寸以及A1、A2、A3、A4各点的角度值θAi ,可以按照比例换算确定其坐标位置,换算公式如下:(2)例如A1点的角度值为64°,可按上述公式换算出A1点的纵坐标值:X A1同理,A2、A3、=216.42mm 、X A4根据上分析和尺寸,可在图1圆柱凸轮零件图10ϕ100ϕ20A2A3A1A40°A1点:64°A2点:112°A3点:248°A4点:296°360°该方法建模基本步骤为:选择一个绘图平面,绘制圆ø100mm→拉伸为ø100mm×100mm 圆柱体→选择穿过圆柱体中心轴线的平面根据换算尺寸绘制圆柱凸轮凹槽轮廓展开曲线S1→在编辑菜单中选择包络命令,将曲线投影到圆柱体外圆面得到凹槽轮廓展开曲线空间曲线S2→利用扫描-切口命令选择凹槽轮廓展开曲线空间曲线为扫引轨迹,绘制10mm×12mm 的矩形作为截面得到圆柱凸轮→孔命令绘制ø20通孔。
注意事项如下:①各点坐标值的正确换算,否则无法精确绘制圆柱凸轮。
②为防止运用包络曲线命令时选错圆柱面,ø20通孔应在最后绘制。
2.2圆柱凸轮环形折弯建模方法环形折弯(Toroidal Bend )命令是一种改变模型形状该方法建模基本步骤为:选择一个绘图平面,绘制100πmm×100mm 的矩形→拉伸100π×100×50mm 长方体选择长方体表面为绘图平面,根据换算尺寸绘制圆柱凸轮凹槽轮廓展开曲线S3→利用扫描-切口命令选择凹槽轮廓展开曲线S3为扫引轨迹,绘制10mm×12mm 的矩形作为截面得到圆柱凸轮凹槽平面展开形状→在“插入”“高级”中选择“环形折弯”命令,在“参照”选项卡下勾选该方法建模基本步骤为:选择一个绘图平面,绘制两个同心圆ø100mm 、ø20mm→拉伸至高度为100mm 的空心圆柱体→插入-模型基准-图形,添加坐标系,根据零件图平面展开所示注尺寸绘制圆柱凸轮凹槽轮廓展开曲线S4→利用可变截面扫描命令选择圆柱体一个端面边线为原点轨迹→点击控制面板上的“草绘”,绘制10mm×12mm的矩形作为截面,同时点击工具-关系,为尺寸S5添加函数关系:sd5=evalgraph (“cam ”,trajpar*360)→移除材料得到圆柱凸轮。