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A spectrometer for measuring particle size distributions in the range of 3 nm to 10 μm

Jieqiong LIU,Jingkun JIANG,Qiang ZHANG,Jianguo DENG,Jiming HAO

《环境科学与工程前沿（英文）》 2016年 第10卷 第1期   页码 63-72 doi: 10.1007/s11783-014-0754-x

摘要： A spectrometer combining electrical mobility sizing and aerodynamic sizing was developed to measure aerosol size distributions in the range of 3 nm to 10 μm. It includes three instruments which cover different size ranges (a nano scanning mobility particle sizer (NSMPS, 3 – 60 nm), a regular scanning mobility particle sizer (RSMPS, 40 – 700 nm), and an aerodynamic particle sizer (APS, 550 nm – 10 μm)). High voltage and sheath flow of the NSMPS and RSMPS were supplied using two home-built control boxes. A LabVIEW program was developed for spectrometer automatic operation. A linear inversion method was applied to correct particle multiple charging effects and to integrate data from the three instruments into a wide-range size distribution. Experiments were conducted to compare distributions in the overlap size ranges measured by three instruments. Good agreement between the NSMPS and RSMPS was achieved after correcting for the difference in counting efficiencies of the two particle counters. Aerodynamic size distributions reported by the APS were converted to mobility size distributions by applying an effective density method. Distributions measured by the RSMPS and APS were consistent in the overlap size range of 550 – 700 nm. A full spectrum in the size range of 3 nm to 10 μm was demonstrated by measuring aerosol generated using a mixture of different sized polystyrene latex spheres.

关键词： spectrometer     particle size distribution     electrical mobility     linear inversion     aerodynamic diameter    

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Particle size distributions, PM

Can DONG, Lingxiao YANG, Chao YAN, Qi YUAN, Yangchun YU, Wenxing WANG

《环境科学与工程前沿（英文）》 2013年 第7卷 第1期   页码 55-65 doi: 10.1007/s11783-012-0411-1

摘要： In this study, we collected particles with aerodynamic diameter≤2.5 μm (PM ) from three different public indoor places (a supermarket, a commercial office, and a university dining hall) in Jinan, a medium-sized city located in northern China. Water-soluble inorganic ions of PM and particle size distributions were also measured. Both indoor and outdoor PM levels (102.3–143.8 μg·m and 160.2–301.3 μg·m , respectively) were substantially higher than the value recommended by the World Health Organization (25 μg·m ), and outdoor sources were found to be the major contributors to indoor pollutants. Diurnal particle number size distributions were different, while the maximum volume concentrations all appeared to be approximately 300 nm in the three indoor locations. Concentrations of indoor and outdoor PM were shown to exhibit the same variation trends for the supermarket and dining hall. For the office, PM concentrations during nighttime were observed to decrease sharply. Among others, , and were found to be the dominant water-soluble ions of both indoor and outdoor particles. Concentrations of in the supermarket and office during the daytime were observed to decrease sharply, which might be attributed to the fact that the indoor temperature was much higher than the outdoor temperature. In addition, domestic activities such as cleaning, water usage, cooking, and smoking also played roles in degraded indoor air quality. However, the results obtained here might be negatively impacted by the small number of samples and short sampling durations.

关键词： indoor air quality     indoor/outdoor ratios     size distributions     particles with aerodynamic diameter≤2.5 μm (PM2.5)     water-soluble ions    

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Numerical analysis of aerodynamic noise radiated from cross flow fan

CHEN Anbang, LI Song, HUANG Dongtao

《能源前沿（英文）》 2008年 第2卷 第4期   页码 443-447 doi: 10.1007/s11708-008-0063-9

摘要： The flow field in a cross flow fan was simulated by solving the 2-D unsteady Reynolds-averaged Navier-Stokes equations. The calculated pressure fluctuations of the blades, the vortex wall, and the rear wall were then used as noise sources to calculate the sound field. The Ffowcs Williams-Hawkings (FW-H) equation was employed to predict the noise field caused by these sources. The predictions show that the rear wall and the vortex wall sources contribute significantly to the total noise and that both the predicted aerodynamic performance and noise agree well with the experimental results.

关键词： predicted aerodynamic     Williams-Hawkings     calculated pressure     aerodynamic performance     unsteady Reynolds-averaged    

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Flutter control effect and mechanism of central-slotting for long-span bridges

YANG Yongxin, GE Yaojun, XIANG Haifan

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 298-304 doi: 10.1007/s11709-007-0039-6

摘要： The flutter control effect and mechanism of central-slotting, which have gradually been adopted in the design and construction of long-span bridges as an effective flutter controlling measure, were investigated with theoretical analysis and wind tunnel test. Five basic girder cross-sections representing five typical aerodynamic configurations were selected and central-slotted with two different slot widths. Then, a series of sectional model tests and theoretical analyses based on the two-dimensional three-degrees-of-freedom coupling flutter analysis method (2 dimension-3 degrees of freedom method, 2d-3DOF method) were carried out to investigate the aerodynamic performance, flutter mechanism and flutter modality of the five basic sections and their corresponding central-slotted sections. The results show that central-slotting can not always improve the aerodynamic stability of bridge structure. The control effect of central-slotting depends on the aerodynamic configuration of the original girder section and the corresponding central-slotting width. If the original section is inappropriate or the slot width is unsuitable, central-slotting will even deteriorate the structural flutter performance. Theoretical investigations indicated that the differences in flutter control effects come from the different formation and evolution of aerodynamic damping, and flutter modality especially the participation level of heaving motion also has a significant influence on the control effect of central-slotting.

关键词： aerodynamic configuration     aerodynamic performance     flutter mechanism     aerodynamic stability     theoretical analysis    

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Aerodynamic stability evolution tendency of suspension bridges with spans from 1000 to 5000 m

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0980-z

摘要： Aerodynamic instability owing to aerostatic and flutter-related failures is a significant concern in the wind-resistant design of long-span suspension bridges. Based on the dynamic characteristics of suspension bridges with spans ranging from 888 to 1991 m, we proposed fitted equations for increasing spans and base frequencies. Finite element models of suspension bridges with increasing span from 1000 to 5000 m were constructed. The structural parameters were optimized to follow the fitted tendencies. To analyze the aerodynamic instability, streamlined single-box section (SBS), lattice truss section (LTS), narrow slotted section (NSS), and wide slotted section (WSS) were considered. We performed three-dimensional (3-D) full-mode flutter analysis and nonlinear aerostatic instability analysis. The flutter critical wind speed continuously decreases with span growth, showing an unlimited approaching phenomenon. Regarding aerostatic instability, the instability wind speed decreases with span to approximately 3000 m, and increases when the span is in the range of 3000 to 5000 m. Minimum aerostatic instability wind speed with SBS or LTS girder would be lower than observed maximal gust wind speed, indicating the probability of aerostatic instability. This study proposes that suspension bridge with span approximately 3000 m should be focused on both aerostatic instability and flutter, and more aerodynamic configuration optimistic optimizations for flutter are essential for super long-span suspension bridges with spans longer than 3000 m.

关键词： suspension bridge     super long-span     finite element model     aerodynamic instability     aerodynamic configuration    

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Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

Zhiwen LIU , Zhengqing CHEN , Gao LIU , Xinpeng SHAO ,

《结构与土木工程前沿（英文）》 2009年 第3卷 第3期   页码 292-298 doi: 10.1007/s11709-009-0048-8

摘要： The aerodynamic interference effects on aerostatic coefficients of twin deck bridges with large span were investigated in detail by means of wind tunnel test. The distances between the twin decks and wind attack angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin decks. The research results have shown that the drag coefficients of the leeward deck are much smaller than that of a single leeward deck. The drag coefficients of a windward deck decrease slightly compared with that of a single deck. The lift and torque coefficients of windward and leeward decks are also affected slightly by the aerodynamic interference of twin decks. And the aerodynamic interference effects on lift and torque coefficients of twin decks can be neglected.

关键词： twin decks     aerodynamic interference effects     aerostatic coefficients     wind tunnel test    

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New response surface model and its applications in aerodynamic optimization of axial compressor blade

LIU Xiaojia, NING Fangfei

《能源前沿（英文）》 2008年 第2卷 第4期   页码 541-549 doi: 10.1007/s11708-008-0077-3

摘要： A parametric method for the axial compressor 2D blade profiles is proposed in which the blade geometries are defined with the parameters commonly used for blade definition, which ensures that the geometric significance is clear and an unreasonable blade profile is not generated. Several illustrations are presented to show the fitting precision of the method. A novel response surface model is proposed which regards the objective distribution function in the vicinity of a sample as normal school, and then generates the response surface function in the whole design space by a linear combination of distribution functions of all the samples. Based on this model, a numerical aerodynamic optimization platform for the axial compressor 2D blade profiles is developed, by which aerodynamic optimization of two compressor blade profiles are presented.

关键词： definition     objective distribution     fitting precision     combination     numerical aerodynamic    

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Aerodynamic interference effects and mitigation measures on vortex-induced vibrations of two adjacent

Xiaoliang MENG, Ledong ZHU, Zhenshan GUO

《结构与土木工程前沿（英文）》 2011年 第5卷 第4期   页码 510-517 doi: 10.1007/s11709-011-0129-3

摘要： By examining the two neighboring Haihe Bridges with semi- and full-closed bridge decks, the aerodynamic interference between the two decks on the vortex-induced vibration (VIV) and the corresponding aerodynamic mitigation measures are investigated via a series of wind tunnel tests with a spring-suspended sectional model aided with computational fluid dynamics (CFD) method. The results show that the VIV responses of both bridges can be significantly affected by the aerodynamic interference and that the extent of the influence varies with the shapes of the windward and leeward decks. The VIV amplitudes of the windward bridge are often fairly close to those of the single bridge. However, those of the leeward bridge are magnified substantially by aerodynamic interference if the same structural and aerodynamic configurations are adopted for the two bridges. Otherwise, the VIV responses are not significantly increased and may even be reduced by the aerodynamic interference if different configurations are employed for the two bridges. Furthermore, an effective combined measure of adding wind barriers and sharpening the wind fairing noses of the two box decks is presented for mitigating both the vertical and torsional VIV responses of the windward and leeward bridges.

关键词： separated parallel decks     vortex-induced vibration     aerodynamic interference     aerodynamic mitigation measure     semi-closed box deck     full-closed box deck    

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Aerodynamic impact of train-induced wind on a moving motor-van

Jiajun HE; Huoyue XIANG; Yongle LI; Bin HAN

《结构与土木工程前沿（英文）》 2022年 第16卷 第7期   页码 909-927 doi: 10.1007/s11709-022-0833-1

摘要： The newly-built single-level rail-cum-road bridge brings the issue of the aerodynamic impact of train-induced wind on road automobiles. This research introduced a validated computational fluid dynamics (CFD) model regarding this concern. Such an aerodynamic impact mechanism was explored; a relationship between the transverse distance between train and motor-van (hereinfafter referred to as van) and the aerodynamic effects on the van was explored to help the optimization of bridge decks, and the relationship between the automobile speed and aerodynamic variations of a van was fitted to help traffic control. The fitting results are accurate enough for further research. It is noted that the relative speed of the two automobiles is not the only factor that influences the aerodynamic variations of the van, even at a confirmed relative velocity, the aerodynamic variations of the van vary a lot as the velocity proportion changes, and the most unfavorable case shows an increase of over 40% on the aerodynamic variations compared to the standard case. The decay of the aerodynamic effects shows that not all the velocity terms would enhance the aerodynamic variations; the coupled velocity term constrains the variation amplitude of moments and decreases the total amplitude by 20%–40%.

关键词： rail-cum-road bridge     aerodynamic impact     train-induced wind     CFD     aerodynamic force     quantitative analysis     fitting    

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Numerical investigation of aerodynamic performance influenced by circumferentially pre-swirling coming

WANG Qikun, CHEN Kangmin

《能源前沿（英文）》 2007年 第1卷 第4期   页码 435-440 doi: 10.1007/s11708-007-0063-5

摘要： Numerical investigation is implemented on aerodynamic performance inside the crossover and de-swirling cascade of a multistage centrifugal compressor. The emphasis is put on the aerodynamic performance influenced by the circumferent

关键词： aerodynamic     investigation     centrifugal     de-swirling     circumferent    

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Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

《化学科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 194-202 doi: 10.1007/s11705-010-1019-2

摘要： In this study, the effect of ethanol addition into pure water and its concentration on bubble diameter, gas hold-up and flow regimes were investigated in an airlift reactor. Air and water with ethanol (concentration ranging from 0%–1%, v/v) were as dispersed and continuous phases, respectively. Superficial gas velocity was considered as an effective parameter. Bubble size distribution was measured by photography and picture analysis at various concentrations of ethanol and various velocities of gas. Alcohol concentration enhancement caused bubble diameter to decrease. Furthermore, the bubbles diameter in pure water was nearly 4 times higher than that of ethanol with concentration of 1% (v/v) and also was 3.4 times higher than that of ethanol with concentration of 0.25% (v/v) at the highest aeration gas velocity inlet. For ethanol solutions in lower superficial gas velocity, a homogenous flow regime was observed. This trend continued to inlet gas velocity of about 0.4 cm/s. The transition flow regime occurred after this datum although in pure water, a homogenous flow regime was observed up to a superficial gas velocity of 0.7 cm/s. The gas hold-up in dilute ethanol solutions were more than (around 2 times) that of pure water and increased with increasing concentration of ethanol in those solutions.

关键词： airlift rector     bubble diameter     gas hold-up     flow regime     ethanol    

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Improvement of aerodynamic stability of suspension bridges with H-shaped simplified stiffening girder

Hiroshi KATSUCHI,Hitoshi YAMADA,Mayuko NISHIO,Yoko OKAZAKI

《结构与土木工程前沿（英文）》 2016年 第10卷 第1期   页码 93-102 doi: 10.1007/s11709-015-0311-0

摘要： Wind-tunnel study on the improvement of aerodynamic stability of simplified suspension-bridge girder structures was conducted with using a 1/40-scaled section model. Objective of the study is the development of an economically superior suspension bridge with 500–1,000 m center span length. The wind-tunnel test showed that an edge-girder type cross section exhibited large amplitude torsional vortex-induced vibration as well as torsional flutter at a low wind speed. Accordingly, aerodynamic countermeasures of open grating deck and triangular faring, and structural countermeasures of center stay, diagonal bracing and mass increase were tried to improve the aerodynamic stability. Finally, feasibility of the best combination to a full-scale bridge was examined by structural analysis.

关键词： suspension bridge     aerodynamics     simplified girder     wind-tunnel test    

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Impacts of different diameter combinations on the temperature of a crude oil pipeline when colocating

Bo YU, Yue SHI, Xin LIU, Jinjun ZHANG, Jinjia WEI,

《能源前沿（英文）》 2010年 第4卷 第2期   页码 192-197 doi: 10.1007/s11708-009-0074-1

摘要： In order to show the effects of different diameter combinations on crude oil temperature when a crude oil pipeline and a products pipeline are laid in one trench, four typical diameter combinations are selected to conduct numerical simulation. After a series of calculations, the minimum mean temperature difference and the maximum temperature difference of the crude oil along the pipelines are obtained. In real pipeline constructions, the effects of other diameter combinations on crude oil temperature can be predicted by the method of linear interpolation to calculate results of the four diameter combinations obtained in this study.

关键词： technology of laying two pipelines in one trench     diameter combinations     crude oil temperature     pipeline interval    

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Effects of slip length and hydraulic diameter on hydraulic entrance length of microchannels with superhydrophobic

Wenchi GONG, Jun SHEN, Wei DAI, Zeng DENG, Xueqiang DONG, Maoqiong GONG

《能源前沿（英文）》 2020年 第14卷 第1期   页码 127-138 doi: 10.1007/s11708-020-0661-8

摘要： This paper investigated effects of slip length and hydraulic diameter on the hydraulic entrance length of laminar flow in superhydrophobic microchannels. Numerical investigations were performed for square microchannels with Re ranging between 0.1 and 1000. It is found that superhydrophobic microchannels have a longer hydraulic entrance length than that of conventional ones by nearly 26.62% at a low Re. The dimensionless hydraulic entrance length slightly increases with the increasing slip length at approximately Re<10, and does not vary with the hydraulic diameter. A new correlation to predict the entrance length in square microchannels with different slip lengths was developed, which has a satisfying predictive performance with a mean absolute relative deviation of 5.69%. The results not only ascertain the flow characteristics of superhydrophobic microchannels, but also suggest that super hydrophobic microchannels have more significant advantages for heat transfer enhancement at a low Re.

关键词： laminar flow     hydraulic entrance length     super hydrophobic surface     slip length     hydraulic diameter    

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Parametric oscillation of cables and aerodynamic effect

Yong XIA, Jing ZHANG, Youlin XU, Yozo FUJINO,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 321-325 doi: 10.1007/s11709-010-0028-z

摘要： This paper addresses the aerodynamic effect on the nonlinear oscillation, particularly parametric vibration of cables in cable-stayed bridges. A simplified 2-DOF model, including a beam and a stayed cable, is formulated first. Response of the cable under global harmonic excitation which is associated with wind speed is obtained using the multiple scales method. Via numerical analysis, the stability condition of the cable in terms of wind speed is derived. The method is applied to a numerical example and a long-span bridge to analyze its all stay cables. It is demonstrated that very large vibration at one of the longest cables in the middle span of the bridge can be parametrically excited when the wind speed is over around 210 km/h (58.5 m/s).

关键词： parametric vibration     cables     cable-stayed bridge     nonlinear vibration    

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标题 作者 时间 类型 操作

A spectrometer for measuring particle size distributions in the range of 3 nm to 10 μm

Jieqiong LIU,Jingkun JIANG,Qiang ZHANG,Jianguo DENG,Jiming HAO

期刊论文

Particle size distributions, PM

Can DONG, Lingxiao YANG, Chao YAN, Qi YUAN, Yangchun YU, Wenxing WANG

期刊论文

Numerical analysis of aerodynamic noise radiated from cross flow fan

CHEN Anbang, LI Song, HUANG Dongtao

期刊论文

Flutter control effect and mechanism of central-slotting for long-span bridges

YANG Yongxin, GE Yaojun, XIANG Haifan

期刊论文

Aerodynamic stability evolution tendency of suspension bridges with spans from 1000 to 5000 m

期刊论文

Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

Zhiwen LIU , Zhengqing CHEN , Gao LIU , Xinpeng SHAO ,

期刊论文

New response surface model and its applications in aerodynamic optimization of axial compressor blade

LIU Xiaojia, NING Fangfei

期刊论文

Aerodynamic interference effects and mitigation measures on vortex-induced vibrations of two adjacent

Xiaoliang MENG, Ledong ZHU, Zhenshan GUO

期刊论文

Aerodynamic impact of train-induced wind on a moving motor-van

Jiajun HE; Huoyue XIANG; Yongle LI; Bin HAN

期刊论文

Numerical investigation of aerodynamic performance influenced by circumferentially pre-swirling coming

WANG Qikun, CHEN Kangmin

期刊论文

Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

期刊论文

Improvement of aerodynamic stability of suspension bridges with H-shaped simplified stiffening girder

Hiroshi KATSUCHI,Hitoshi YAMADA,Mayuko NISHIO,Yoko OKAZAKI

期刊论文

Impacts of different diameter combinations on the temperature of a crude oil pipeline when colocating

Bo YU, Yue SHI, Xin LIU, Jinjun ZHANG, Jinjia WEI,

期刊论文

Effects of slip length and hydraulic diameter on hydraulic entrance length of microchannels with superhydrophobic

Wenchi GONG, Jun SHEN, Wei DAI, Zeng DENG, Xueqiang DONG, Maoqiong GONG

期刊论文

Parametric oscillation of cables and aerodynamic effect

Yong XIA, Jing ZHANG, Youlin XU, Yozo FUJINO,

期刊论文