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基于特征的流场数据挖掘 被引量:6
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作者 解利军 张帅 +2 位作者 张继发 郑耀 周迪斌 《空气动力学学报》 EI CSCD 北大核心 2010年第5期540-546,共7页
将数据挖掘技术应用于流场分析,有可能挖掘出常规数值方法难以发现的复杂流动规律。流场数据与传统数据库数据不同,通常组织为不规则的空间离散点和单元。为建立流场数据挖掘的统一范式,提出了基于特征的流场数据挖掘流程,并设计了两类... 将数据挖掘技术应用于流场分析,有可能挖掘出常规数值方法难以发现的复杂流动规律。流场数据与传统数据库数据不同,通常组织为不规则的空间离散点和单元。为建立流场数据挖掘的统一范式,提出了基于特征的流场数据挖掘流程,并设计了两类相应的数据模型组织方式:邻域时空盒模型和连接图模型。使用该框架,对特定Rayleigh-Benard对流现象的数值计算结果进行了关联规则分析。其中涡特征提取使用λ2准则,关联规则提取使用Apriori算法。实验挖掘到了一些非平凡的流场规则,证明了该方法的有效性。 展开更多
关键词 流场数据分析 数据挖掘 APRIORI算法 λ2准则 Rayleigh-Benard对流现象
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一种处理离散流场数据的神经网络模型 被引量:1
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作者 唐洪武 徐友仁 《水动力学研究与进展(A辑)》 CSCD 北大核心 2000年第2期221-228,共8页
根据流体运动的连续性 ,提出“空间邻域矢量相近”准则 ,建立人工神经网络模型 ,对由试验获取的异常离散流速数据以及网格化插补引起的误差进行修补 ,通过数值试验的方法 ,对该网络模型进行验证 ,并对产生误差的主要控制参数进行分析。
关键词 人工神经网络 流体连续性 离散流场数据
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基于LIC的海洋流场数据可视化技术研究及应用
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作者 刘畅 宋浩全 《数字技术与应用》 2016年第6期136-137,共2页
实现了海洋流场数据的可视化。整个过程首先采用双线性插值对数据进行预处理,然后使用LIC算法对各像素点进行纹理运算,得到输出图像的纹理信息,将纹理信息与颜色信息进行融合后得出各像素点的最终像素值,最终通过Open GL将流线的绘制结... 实现了海洋流场数据的可视化。整个过程首先采用双线性插值对数据进行预处理,然后使用LIC算法对各像素点进行纹理运算,得到输出图像的纹理信息,将纹理信息与颜色信息进行融合后得出各像素点的最终像素值,最终通过Open GL将流线的绘制结果显示出来。实验结果验证了上述方法的可行性。 展开更多
关键词 流场数据可视化 线卷积积分 双线性插值
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面向沉浸式流场可视化的多视图数据管理方法 被引量:1
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作者 洪韬濮 杨超 +3 位作者 吴亚东 张晓蓉 王昉 王赋攀 《计算机工程与应用》 CSCD 北大核心 2023年第4期312-319,共8页
由于沉浸式环境下的三维交互方式对二维界面操作不够友好,使得依赖于二维列表界面的流场数据管理任务变得复杂且低效。为了实现沉浸式虚拟环境下对流场数据高效的组织和管理,增强用户对流场空间信息的理解,提出一种基于多视图结合交互... 由于沉浸式环境下的三维交互方式对二维界面操作不够友好,使得依赖于二维列表界面的流场数据管理任务变得复杂且低效。为了实现沉浸式虚拟环境下对流场数据高效的组织和管理,增强用户对流场空间信息的理解,提出一种基于多视图结合交互的沉浸式流场可视化数据块管理方法。该方法构建了一个三维小视图用于提供场景概览,并通过“主视图交互+小视图辅助”“小视图交互+主视图反馈”等多种多视图组合交互方式完成对多块流场数据的管理交互操作。最后构建了一个基于手势的沉浸式流场可视化系统,定义多项交互任务,从学习时长、完成时间和用户反馈几个方面对比了多视图方法和传统交互方法差异。实验结果表明,相比于传统交互方法,多视图方法可以显著提高数据管理任务的效率。 展开更多
关键词 沉浸式流场可视化 多块流场数据 微型世界 手势交互
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大规模数据流场并行可视化研究进展
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作者 江时俊 王浩 +1 位作者 董增川 王敏 《治淮》 2022年第1期22-24,共3页
水动力学数值模拟是研究水流运动的重要科学方法,可视化是分析数值模拟计算结果的关键方法。本文从并行模式层面回顾了流场可视化现状,并对比了后处理与原位可视化两种模式的优劣势,着重阐述了原位可视化的实现方法与应用案例。针对目... 水动力学数值模拟是研究水流运动的重要科学方法,可视化是分析数值模拟计算结果的关键方法。本文从并行模式层面回顾了流场可视化现状,并对比了后处理与原位可视化两种模式的优劣势,着重阐述了原位可视化的实现方法与应用案例。针对目前流场可视化技术中的不足,指出今后流场并行可视化应从精确性、时效性与交互性等方面加强研究。 展开更多
关键词 大规模流场数据 并行可视化 后处理模式 原位模式
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基于CFD流场预计算的短期风速预测方法 被引量:65
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作者 李莉 刘永前 +1 位作者 杨勇平 韩爽 《中国电机工程学报》 EI CSCD 北大核心 2013年第7期27-32,22,共6页
风电功率预测有利于减轻风力发电对电网的冲击、提高电网运行的安全性和经济性,准确预测风速是风电功率预测的关键。提出一种基于计算流体力学(computational fluiddynamics,CFD)流场预计算(CFD pre-calculated flow fields,CPFF)的短... 风电功率预测有利于减轻风力发电对电网的冲击、提高电网运行的安全性和经济性,准确预测风速是风电功率预测的关键。提出一种基于计算流体力学(computational fluiddynamics,CFD)流场预计算(CFD pre-calculated flow fields,CPFF)的短期风速预测方法:首先,对可能出现的风电场来流条件离散化,并利用CFD模型对不同来流条件下的流场进行预计算;其次,提取各来流条件下流场特定位置的风速和风向分布,组成流场特性数据库;最后,以中尺度数值天气预报数据为输入参数,利用数据库插值预测风电机组轮毂高度的风速和风向。以中国北方某风电场为例,采用文中方法进行为期一年的提前24小时风速预测。通过与风机实测风速数据对比,结果表明:各台机组轮毂高度的预测风速年平均绝对误差小于2 m/s,年均方根误差小于2.5m/s,而且误差越小的预测风速出现的概率越大。所提预测方法不但预测精度高、稳定性好,而且由于复杂的流场计算在预测前完成,预测过程简单、耗时少,工程实用性强。 展开更多
关键词 短期风速预测 计算流体力学模型 预计算 流场特性数据 风电功率预测
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基于MIKE21FM数值模拟的某灌区引水口布置优化 被引量:4
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作者 罗铭 黄尔 李刚 《水电能源科学》 北大核心 2018年第3期118-122,共5页
鉴于引水渠道引水口附近存在较为复杂的流场,且该流场对引水口附近的堤防建设有显著影响,利用MIKE21FM对乌苏里江某引水口进行数值模拟分析,得到了渠道分流比和引水口附近水面线、流速、流向等详细的流场数据。结果表明,渠道分流比过大... 鉴于引水渠道引水口附近存在较为复杂的流场,且该流场对引水口附近的堤防建设有显著影响,利用MIKE21FM对乌苏里江某引水口进行数值模拟分析,得到了渠道分流比和引水口附近水面线、流速、流向等详细的流场数据。结果表明,渠道分流比过大,渠道进口处水面流速梯度较大,水流出现的侧向收缩产生了局部水头损失,不利于水流的平稳流动,据此提出了两种优化方案,并进行了数值试验验证,确定了最优方案为方案2,可有效减少局部水头损失。 展开更多
关键词 引水口 流场数据 MIKE21FM 数值模拟 优化
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某工程吹填泥沙堆积数值模拟及施工方法优化 被引量:3
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作者 罗铭 徐小迟 +1 位作者 丁锐 侯鹏程 《水电能源科学》 北大核心 2018年第7期108-111,共4页
在实际近岸吹填工程中,由于无法形成有效的围堰保护导致吹填沙流失、水质污染等严重后果,进而影响施工项目的整体建设,故利用Mike21FM和Mike21ST模型对非洲某吹填工程进行数值模拟,得到该吹填工程附近海域的水面线、流速、泥沙淤积等流... 在实际近岸吹填工程中,由于无法形成有效的围堰保护导致吹填沙流失、水质污染等严重后果,进而影响施工项目的整体建设,故利用Mike21FM和Mike21ST模型对非洲某吹填工程进行数值模拟,得到该吹填工程附近海域的水面线、流速、泥沙淤积等流场数据,并基于模拟结果对施工方法进行改进。结果表明,施工期间,排沙管口附近水面高程会产生波动且管口两侧流速较大,致使排沙方向偏移,影响最终吹填效果;优化后的施工方法可有效完成吹填任务。 展开更多
关键词 施工方法优化 吹填工程 流场数据 数值模拟
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基于聚类的流面自动布局及生成算法 被引量:3
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作者 唐烨 解利军 +2 位作者 桂立业 何丽莎 郑耀 《计算机工程与应用》 CSCD 北大核心 2018年第12期264-270,共7页
基于流面的流场可视化方法是科学数据可视化的重要分支,在航空航天等领域有着重要的应用。但现有的可视化方法需要人工在流场中布置种子线,往往难以布置在有代表性区域,不能生成表现力丰富的流面。提出一种基于聚类的种子线自动布线及... 基于流面的流场可视化方法是科学数据可视化的重要分支,在航空航天等领域有着重要的应用。但现有的可视化方法需要人工在流场中布置种子线,往往难以布置在有代表性区域,不能生成表现力丰富的流面。提出一种基于聚类的种子线自动布线及流面生成法,通过对流场中速度场的曲率、梯度以及坐标位置间的比较,量化两点间相似度,随后进行聚类实现流场分区。然后在每个分区中心布置种子线。最后积分生成流面。实验显示,该方法生成的流面能表达流场的主要流动结构,其布线结果可以直接使用,也可以作为进一步精细分析时人工布线位置的参考。 展开更多
关键词 流场数据聚类 流面 K-MEANS 科学可视化
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Discussion of Grid Generation for Catamaran Resistance Calculation 被引量:11
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作者 邓锐 黄德波 +2 位作者 李佳 程宣恺 于雷 《Journal of Marine Science and Application》 2010年第2期187-191,共5页
In order to get some useful parameters for grid generation of catamaran, the CFD software FLUENT is used to investigate the main effects of grid generation on flow field calculation. The influences of some elements ar... In order to get some useful parameters for grid generation of catamaran, the CFD software FLUENT is used to investigate the main effects of grid generation on flow field calculation. The influences of some elements are investigated with a series of calculations in the present paper, and some alteratives are proposed. The proposed alteratives based on the analysis of the effects are used for a catamaran resistance calculation, comparisons of the calculated results with experimental data show good agreement. It shows that the research result of this paver is useful for the numerical calculation of catamaran. 展开更多
关键词 CATAMARAN RESISTANCE CALCULATION grid generation
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Original or Western Imitation: The Case of Arab Theatre
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作者 Abdulaziz H. Alabdullah 《Journal of Literature and Art Studies》 2014年第9期749-754,共6页
When discussing the roots of Arab theatre, we find ourselves confronting two main streams of thought. The first one, represented by prominent Arab writers like Najib Mahfuz, Abbas A1-Aqqad, M. Badawi, and other critic... When discussing the roots of Arab theatre, we find ourselves confronting two main streams of thought. The first one, represented by prominent Arab writers like Najib Mahfuz, Abbas A1-Aqqad, M. Badawi, and other critics, rejects the theory that an Arab theatre existed before the mid-19th century. The second stream, represented by prominent scholars like Ali A1-Rai, Ibrahim Hamada and S. Moreh, see modern Arab theatre as part of a continuum, emphasizing of some elements of dramatic manifestations in Arab literary heritage. This paper intends to examine these two streams, their evidences and arguments. Such examination will shed some light on the origin of Arab theatre as a literary genre, and how it was influenced, if any, by Western theatrical heritage. Thus, answering the main question of this paper, whether Arab theatre is original or simply a Western imitation. 展开更多
关键词 ORIGINALITY MODERNISM IMITATION HERITAGE
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Bed Load Transport Rates during Scouring and Armoring Processes 被引量:6
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作者 YANG Fengguang LIU Xingnian CAO Shuyou HUANG Er 《Journal of Mountain Science》 SCIE CSCD 2010年第3期215-225,共11页
Dambreak-induced bed scouring may undermine the foundation of bridge piers and other structures,and that destruction can pose a serious threat.Consequently,this paper aims at exploring the mechanisms of scouring and a... Dambreak-induced bed scouring may undermine the foundation of bridge piers and other structures,and that destruction can pose a serious threat.Consequently,this paper aims at exploring the mechanisms of scouring and armoring.Firstly,the incipient velocity for nonuniform sediment particles was studied,and a formula was derived based on the angle of repose of nonuniform sediment.The results showed that the mechanism of incipient motion for sand and fine gravel differed from that for coarse gravel and cobbles.Also,comparison between experimental and field data shows that the results from the proposed formula agree well with those observed for all conditions.Secondly,a birth-death,immigration-emigration Markov process was developed to describe the bed load transport rate associated with scouring and armoring.The comparison between experimental data and computed results shows that our model can predict the bed load transport rate,although there may be some limitations,the chief of which is that there are many variables in the model to be determined through experiment.This makes its application in river engineering inconvenient. 展开更多
关键词 Nonuniform sediment angle of repose bed scour armoring incipient velocity bed loadtransport
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Vorticity Budget Study on the Seasonal Upper Circulation in the Northern South China Sea from Altimetry Data and a Numerical Model 被引量:1
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作者 CAI Shuqun ZHENG Shu HE Yinghui 《Journal of Ocean University of China》 SCIE CAS 2012年第4期455-464,共10页
Based on the EOF analyses of Absolute Dynamic Topography satellite data, it is found that, in summer, the northern South China Sea (SCS) is dominated by an anticyclonic gyre whilst by a cyclonic one in winter. A con... Based on the EOF analyses of Absolute Dynamic Topography satellite data, it is found that, in summer, the northern South China Sea (SCS) is dominated by an anticyclonic gyre whilst by a cyclonic one in winter. A connected single-layer and two-layer model is employed here to investigate the dynamic mechanism of the circulation in the northern SCS. Numerical experi- ments show that the nonlinear term, the pressure torque and the planetary vorticity adveetion play important roles in the circulation of the northern SCS, whilst the contribution by seasonal wind stress curl is local and limited. Only a small part of the Kuroshio water intrudes into the SCS, it then induces a positive vorticity band extending southwestward from the west of the Luzon Strait (LS) and a negative vorticity band along the 200 m isobath of the northern basin. The positive vorticity field induced by the local summer wind stress curl is weaker than that induced in winter in the northern SCS. Besides the Kuroshio intrusion and monsoon, the water trans- ports via the Sunda Shelf and the Sibutu Passage are also important to the circulation in the northern SCS, and the induced vorticity field in summer is almost contrary to that in winter. The strength variations of these three key factors (Kuroshio, monsoon and the water transports via the Sunda Shelf and the Sibutu Passage) determine the seasonal variations of the vorticity and eddy fields in the northern SCS. As for the water exchange via the LS, the Kuroshio intrusion brings about a net inflow into the SCS, and the monsoon has a less effect, whilst the water transports via the Sunda Shelf and the Sibutu Passage are the most important influencing factors, thus, the water exchange of the SCS with the Pacific via the LS changes dramatically from an outflow of the SCS in summer to an inflow into the SCS in winter. 展开更多
关键词 KUROSHIO South China Sea circulation mosoon VORTICITY bifurcation of North Equatorial Current
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Numerical Prediction of Flow Patterns after Various Pipe Fittings
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作者 Andreas Swienty Raja Abou Ackl Paul Uwe Thamsen 《Journal of Mechanics Engineering and Automation》 2015年第10期542-548,共7页
An accurate prediction of flows using CFD depends on a large number of factors. In addition to discretizing the flow region, the correct definition of boundary or initial conditions and the choice of suitable numerica... An accurate prediction of flows using CFD depends on a large number of factors. In addition to discretizing the flow region, the correct definition of boundary or initial conditions and the choice of suitable numerical methods, the applied turbulence model influences the results of the flow simulation to a great extent. Therefore, a validation of the results with the experimental data is of great importance for a correct selection of a turbulence model. It is the scope of this paper to assess different turbulence models for the simulation of pipe flows. The calculation results of pipe flows through a combination of 90~ elbows and a 1/3 segmental orifice are compared with experimental measurement results. This has the advantage that the suitability of the turbulence models for simulating both shear and swirl flows can be investigated. Thus, the k-ω, k-ε model and the Launder Reece Rodi Reynolds stress model are compared with each other and experimental results. Furthermore, this investigation is extended through including a much more c detached-eddy simulation. This model provides better prediction of the flow by resolving the large eddies and modeling the small ones. The experimental results originate from LDV measurements over the entire pipe cross-section. This measuring method provides velocity vectors over the measured surface. 展开更多
关键词 CFD turbulence models k-ε k-ω LRR DES.
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Simulation and experiment of starting transient flow field of the hydrostatic bearing based on dynamic mesh method
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作者 张艳芹 Kong Xiangbin +3 位作者 Guo Lili Yu Xiaodong Dai Chunxi Shao Junpeng 《High Technology Letters》 EI CAS 2017年第3期298-305,共8页
A new method is developed to assess and analyze the dynamic performance of hydrostatic bearing oil film by using an amulets-layer dynamic mesh technique. It is implemented using C Language to compile the UDF program o... A new method is developed to assess and analyze the dynamic performance of hydrostatic bearing oil film by using an amulets-layer dynamic mesh technique. It is implemented using C Language to compile the UDF program of a single oil film of the hydrostatic bearing. The effects of key lubrication parameters of the hydrostatic bearing are evaluated and analyzed under various working conditions,i.e. under no-load,a load of 40 t,a full load of 160 t,and the rotation speed of 1r/min,2r/min,4r/min,8r/min,16r/min,32r/min. The transient data of oil film bearing capacity under different load and rotation speed are acquired for a total of 18 working conditions during the oil film thickness changing. It allows the effective prediction of dynamic performance of large size hydrostatic bearing. Experiments on hydrostatic bearing oil film have been performed and the results were used to define the boundary conditions for the numerical simulations and validate the developed numerical model. The results showed that the oil film thickness became thinner with the increase of the operating time of the hydrostatic bearing,both the oil film rigidity and the oil cavity pressure increased significantly,and the increase of the bearing capacity was inversely proportional to the cube of the change of the film thickness. Meanwhile,the effect of the load condition on carrying capacity of large size static bearing was more important than the speed condition. The error between the simulation value and the experimental value was 4.25%. 展开更多
关键词 hydrostatic bearing dynamic mesh transient data oil pad UDF
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基于多维Fourier分析研究流场的空间尺度分解
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作者 刘浪 陈瑜 谢锡麟 《复旦学报(自然科学版)》 CAS CSCD 北大核心 2014年第5期616-625,共10页
提出了一种对流场数据进行尺度分解的方法.该方法通过移动一定宽度的矩形网格截取流场,通过傅里叶变换及能量分布判断所截取流场的尺度信息是否和矩形网格尺度相符合,然后用不同宽度的网格对整个流场进行处理,并通过阈值控制,实现了流... 提出了一种对流场数据进行尺度分解的方法.该方法通过移动一定宽度的矩形网格截取流场,通过傅里叶变换及能量分布判断所截取流场的尺度信息是否和矩形网格尺度相符合,然后用不同宽度的网格对整个流场进行处理,并通过阈值控制,实现了流场不同尺度的分解.将该方法用于二维和三维流场数据的尺度分解,并进行了验证. 展开更多
关键词 多维Fourier变换 空间尺度分解 流场数据处理
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A surface-based hiding function linking flume and field data 被引量:1
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作者 ZHANG LiGuo FU XuDong DUAN Jennifer G 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第10期1560-1569,共10页
The quantification of the sheltering and exposure effects of non-uniform sediments has been widely achieved through hiding function models. Big challenge exists so far in the model parameter that is highly variable an... The quantification of the sheltering and exposure effects of non-uniform sediments has been widely achieved through hiding function models. Big challenge exists so far in the model parameter that is highly variable and differs greatly between laboratory flumes and field streams. This paper presents an improved surface-based hiding fimction. The force balance for particle inception was formulated and the allocation of the overall bed shear stress into each group of sediments was mimicked. The new hiding function was examined against and agrees well with the documented field and flume data. It was shown that the hiding fimction is closely related to the relative flow depth and the reference elevation in the velocity profile in addition to the bed material gradation. The power law of velocity profile that applies to both flume flows and natural streams can link the flume and field data together. The hiding function with b = 1/6 and b = 1/2 is applicable to natural streams and laboratory flumes, respectively. The value orb = 0.263 also works well for gravel bed rivers. The range of the reference elevation, namely z0 = 0.4Dm-1.4Dm, is recommended for either the flume or field data. The new hiding function contributes to addressing clearer physical meanings and a useful perspective for further improvement. 展开更多
关键词 hiding function relative flow depth flume and field data reference elevation
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Progress in research on mixing techniques for transverse injection flow fields in supersonic crossflows 被引量:9
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作者 Wei HUANG Li YAN 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2013年第8期554-564,共11页
The transverse injection flow field has an important impact on the flowpath design of scramjet engines. At present a combination of the transverse injection scheme and any other flame holder has been widely employed i... The transverse injection flow field has an important impact on the flowpath design of scramjet engines. At present a combination of the transverse injection scheme and any other flame holder has been widely employed in hypersonic propulsion systems to promote the mixing process between the fuel and the supersonic freestream; combustion efficiency has been improved thereby, as well as engine thrust. Research on mixing techniques for the transverse injection flow field is summarized from four aspects, namely the jet-to-crossflow pressure ratio, the geometric configuration of the injection port, the number of injection ports, and the injection angle. In conclusion, urgent investigations of mixing techniques of the transverse injection flow field are pro- posed, especiaUy data mining in the quantitative analytical results for transverse injection flow field, based on results from multi-objective design optimization theory. 展开更多
关键词 Aerospace propulsion system Transverse injection MIXING Supersonic crossflow
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Study on coupled 3D seepage and stress fields of the complex channel project 被引量:5
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作者 ZHONG DengHua ZHANG XiaoXin +3 位作者 AO XueFei WANG XiaoLing TONG DaWei REN BingYu 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第8期1906-1914,共9页
Seepage is a vital reason that may bring many adverse consequences such as subsidence,inclination and fracture to the channel,and is harmful to the safety and stability of the channel.Thus,a 3D visualization model is ... Seepage is a vital reason that may bring many adverse consequences such as subsidence,inclination and fracture to the channel,and is harmful to the safety and stability of the channel.Thus,a 3D visualization model is established for the engineering geological information of the research channel section by using NURBS-TIN-BRep hybrid data structure.Coupled with the VOF(volume of fluid)method,the N-S(Navier-Stokes)equations are applied to seepage simulation of the research channel section.Then the stability of the channel is studied coupled with the seepage simulation results,to comprehensively analyze the stress and displacement conditions of the channel under the impact of different factors such as seepage and underground goafs.The results of this study illustrate that the channel seepage has great influence on its stability,especially on the displacement field:it will lead to a significant sedimentation to the foundation.Therefore,during the practical construction,it is suggested that the certain part of the channel should be reinforced and effective seepage control measures should be taken. 展开更多
关键词 hydro-mechanical coupling VOF(volume of fluid)method seepage analysis stability analysis 3D geological model
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