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Effect of inlet box on performance of axial flow fans

LI Jingyin, TIAN Hua, YUAN Xiaofang

《能源前沿（英文）》 2008年第2卷第4期页码 390-394 doi: 10.1007/s11708-008-0087-1

摘要： Numerical investigations on 3D flow fields in an axial flow fan with and without an inlet box have been extensively conducted, focusing on the variation of fan performance caused by the internal flow fields and the velocity evenness at the exit of the inlet box. It is interesting to find that although the inlet box is well designed in accordance with basic design principles, there is a flow separation region in it. Furthermore, this flow separation and the resulting uneven velocity distribution at the exit lead to some decrease in the efficiency and an increase in the total pressure rise of the fan. This research shows that the inlet box needs further improvement and such a check on the flow fields is of value for the design of inlet boxes.

关键词： box velocity distribution accordance Numerical variation

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Investigation on available wind energy at Tungku beach

M. G. YAZDANI, M. A. SALAM

《能源前沿（英文）》 2012年第6卷第3期页码 275-279 doi: 10.1007/s11708-012-0194-x

摘要： In this paper, wind velocities and directions (sea and land) are recorded in different days and times. The data collected were compared with the weather data from the Brunei Darussalam Meteorological Service (BDMS) and the findings of other researchers and were found to be in good agreement. The potential of wind energy is predicted from the available data collected. The average generated power (forenoon and afternoon) is found to be 25 (mean) and 18 W (median), 101 (mean) and 73 W (median), 912 (mean) and 660 W (median), 10137 (mean) and 7331 W (median) for a rotor with a diameter of 2.5, 5, 15 and 50 m, respectively. The power density for wind farming is found to be 0.26 (mean) and 0.19 (median), 0.31 (mean) and 0.22 (median) for the rotor whose diameter is 2.5 and 50 m, respectively, while the average values are found to be 0.28 (mean) and 0.2 (median) for the rotor whose diameter is 5 and 15 m.

关键词： wind velocity temperature tower height power density Raleigh distribution electrical power

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Simulation of horizontal slug-flow pneumatic conveying with kinetic theory

GU Zhengmeng, GUO Liejin

《能源前沿（英文）》 2007年第1卷第3期页码 336-340 doi: 10.1007/s11708-007-0050-6

摘要： Wavelike slug-flow is a representative flow type in horizontal pneumatic conveying. Kinetic theory was introduced to establish a 3D kinetic numerical model for wavelike slug gas-solid flow in this paper. Wavelike motion of particulate slugs in horizontal pipes was numerically investigated. The formation and motion process of slugs and settled layer were simulated. The characteristics of the flow, such as pressure drop, air velocity distribution, slug length and settled layer thickness, and the detailed changing characteristics of slug length and settled layer thickness with air velocity were obtained. The results indicate that kinetic theory can represent the physical characteristics of the non-suspension dense phase flow of wavelike slug pneumatic conveying. The experiment in this paper introduced a new idea for the numerical calculation of slug-flow pneumatic conveying.

关键词： velocity distribution detailed slug-flow gas-solid theory

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气流速度对感烟火灾探测器响应灵敏度的影响

谢启源,苏国锋,袁宏永,张永明

《中国工程科学》 2005年第7卷第11期页码 76-80

摘要：

针对地下车库、空调出风口等存在高速气流的特殊场所，利用火灾探测综合模拟实验平台，根据气流是否影响烟颗粒生成过程，分别设计2种实验方案，分析比较了光电型与离子型两种感烟火灾探测器在不同气流条件下的响应灵敏度。实验结果表明，在烟颗粒生成过程不受气流影响的情况下，两种感烟探测器的响应灵敏度均随气流速度增大而下降。在气流影响烟颗粒生成过程的情况下，光电感烟探测器的灵敏度依然随着气流速度的增大而迅速下降；而离子型感烟探测器的灵敏度受气流速度影响较小，在高速气流条件下依然保持较高的灵敏度。综合分析表明，离子感烟探测器较适合在高速气流环境中工作。

关键词：气流速度感烟火灾探测器烟颗粒粒径分布

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Three-dimensional numerical simulation of flow in trapezoidal cutthroat flumes based on FLOW-3D

Danjie RAN, Wene WANG, Xiaotao HU

《农业科学与工程前沿（英文）》 2018年第5卷第2期页码 168-176 doi: 10.15302/J-FASE-2018217

摘要： To solve the common problem of flumes flow-measurement accuracy without sacrificing water head, a new type of trapezoidal cutthroat flume to measure the discharge in terminal trapezoidal channels is presented. Using the computational fluid dynamic method, three-dimensional flow fields in trapezoidal cutthroat flumes were simulated using the RNG three-dimensional turbulence model along with the TruVOF technique. Simulations were performed for 12 working conditions, with discharges up to 0.075 m ·s to determine hydraulic performance. Experimental data for the trapezoidal cutthroat flume in terminal trapezoidal channel were also obtained to validate the simulation results. Velocity distribution of the flume obtained from simulation analyses were compared with observed results based on time-averaged flow field and comparison yielded a solid agreement between results from the two methods, with relative error below 10%. The results indicated that the Froude number and the longitudinal average velocity increased along the convergence section and decreased in the divergent section. In the upper throat, the Froude number was less than 0.5, which meets the water measurement requirement, and the critical flow appeared near the throat section. The maximum water head loss of the trapezoidal cutthroat flume was less than 9% of the total head, compared to the rectangular cutthroat flume, and head loss of trapezoidal cutthroat flume was significantly less. Regression models developed for upstream depth versus discharge under different working conditions were satisfactory, with a relative error of less than 2.06%, which meets the common requirements of flow measurement in irrigation areas. It was concluded that trapezoidal cutthroat flumes can improve flow-measurement accuracy without sacrificing water head.

关键词： distribution of velocity Froude number head loss stage-discharge relationship trapezoidal cutthroat flume

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Design and characteristics of electric supercharger for diesel engine acceleration by additional rapid air injection

YAO Chun-de, ZHOU Hong-xiu

《机械工程前沿（英文）》 2006年第1卷第4期页码 409-412 doi: 10.1007/s11465-006-0048-5

摘要： The ES (electric supercharger) driven by a high-speed brushless motor was developed to solve the problem of smoke caused by the turbocharger s sluggish response during acceleration. Its rotation speed was from 6 000 r/min to 24 000 r/min, and the maximum flux was 0.1 kg/s. The structural design of the electric supercharger is novel, which makes it easier to set the lubricating installation and to assemble. The velocity distribution at the outlet of the electric supercharger is determined by hot-wire anemometry under various rotation speeds in steady state. Furthermore, the trends of the flux and charge rate with various speeds were analyzed. In addition, the transient response was detected from the motor setup to smooth running within 10 s, 15 s, 20 s and 25 s respectively, and the characteristic of the transient flux is under pilot study. Research results indicate that the electric supercharger can respond rapidly with the great flux, and it is independent of the operating conditions of a diesel engine. Therefore, it is a feasible way to reduce smoke emission and improve the acceleration performance.

关键词： acceleration velocity distribution high-speed brushless turbocharger electric supercharger

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Prediction of the shear wave velocity

Amoroso SARA

《结构与土木工程前沿（英文）》 2014年第8卷第1期页码 83-92 doi: 10.1007/s11709-013-0234-6

摘要： The paper examines the correlations to obtain rough estimates of the shear wave velocity from non-seismic dilatometer tests (DMT) and cone penetration tests (CPT). While the direct measurement of is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of from the parameters (material index), (horizontal stress index), (constrained modulus) are more reliable and consistent than the CPT predictions from (cone resistance), presumably because of the availability, by DMT, of the stress history index .

关键词： horizontal stress index shear wave velocity flat dilatometer test cone penetration test

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Method of internal 3D flow field numerical simulation for hydrodynamic torque converter

SHANG Tao, ZHAO Dingxuan, ZHANG Yuankun, GUO Xiangen, SHI Xiangzhong

《机械工程前沿（英文）》 2008年第3卷第1期页码 86-90 doi: 10.1007/s11465-008-0012-7

摘要： To enhance the performance of a hydrodynamic torque converter and thoroughly understand the trait of inside flow, a numerical simulation method of internal 3D flow for the three-element centrifugal hydrodynamic torque converter was systematically researched and expatiated in this paper. First, the internal flow field of each impeller was calculated. The curves that illustrate the relationships between the pressure differences of the inlet and outlet versus flux were drawn. Second, the concurrent working point of each impeller was approximately estimated. Finally, a calculation was performed considering the influence on each impeller. The flow field of a working point was solved by multiple calculations and the actual working condition was gradually determined. The pressure and velocity distributions of the flow field were proposed. The performance parameters of the hydrodynamic torque converter were predicted. The calculation method, and the proposed pressure and velocity distribution of the flow field, have practical significance for the design and improvement of a hydrodynamic torque converter.

关键词： velocity distribution calculation numerical simulation three-element centrifugal converter

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Discrete element method modeling of corn-shaped particle flow in rectangular hopper

He TAO, Baosheng JIN, Wenqi ZHONG, Xiaofang WANG,

《结构与土木工程前沿（英文）》 2010年第4卷第2期页码 267-275 doi: 10.1007/s11709-010-0035-0

摘要： Discrete element method (DEM) was developed to simulate the corn-shaped particles flow in the hopper. The corn-shaped particle was described by four overlapping spheres. Contact force and gravity force were considered when establishing the model. In addition, flowing characteristic of particles in the hopper was studied. The effect of friction coefficient on the wall pressure, voidage and velocity distribution was analyzed. The results show that the discharge rate decreases with the friction coefficient increasing; and the “over-pressure” phenomenon occurs in the discharging process for two different friction coefficients. The voidage also increases as the friction coefficient increasing. And the velocity distribution is more uniformity and is closer to the mass flow with the friction coefficient deceasing.

关键词： discrete  element   method  (DEM)   non-spherical voidage pressure velocity distribution hopper

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基于惯性能时空最优分布的高加速轻载机构精密定位方法 Article

陈新,白有盾,杨志军,高健,陈贡发

《工程（英文）》 2015年第1卷第3期页码 391-398 doi: 10.15302/J-ENG-2015063

摘要：

高速运动精密定位是微电子封装设备中高加速轻载执行机构的基本运动需求。本文推导了高加速机构瞬态非线性动力学响应方程，揭示了刚度、频率、阻尼 (与材料空间布局相关) 和驱动频率 (与运动规划相关) 是主要影响因素。据此，在满足高加速机构精密定位的条件下，笔者提出了一种基于最优非线性动力学响应的结构优化和速度规划新方法。在结构优化中，首先分析了目前流行的基于等效静态载荷的柔性多体动力学优化方法未充分考虑惯性载荷的不足，然后提出了基于等效模态的柔性多体动力学最优动态响应优化新方法；在速度规划上，针对传统的几何光滑方法不能反映系统动态特性的缺陷，提出了基于变边界条件非线性动力学响应优化的速度规划新方法。将所提方法应用到高速固晶焊头的优化设计中，通过结构优化，降低振幅超过20%，再经非对称变加速规划，缩短定位时间超过40%。本文提出的方法为微电子封装类装备等高加速轻载机构精密定位的实现提供了有效的理论支撑和解决途径。

关键词：高加速轻载机构精密定位时空分布惯性能等效静态载荷方法速度规划

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High velocity impact of metal sphere on thin metallic plate using smooth particle hydrodynamics (SPH)

Hossein ASADI KALAMEH, Arash KARAMALI, Cosmin ANITESCU, Timon RABCZUK

《结构与土木工程前沿（英文）》 2012年第6卷第2期页码 101-110 doi: 10.1007/s11709-012-0160-z

摘要： The modeling of high velocity impact is an important topic in impact engineering. Due to various constraints, experimental data are extremely limited. Therefore, detailed numerical simulation can be considered as a desirable alternative. However, the physical processes involved in the impact are very sophisticated; hence a practical and complete reproduction of the phenomena involves complicated numerical models. In this paper, we present a smoothed particle hydrodynamics (SPH) method to model two-dimensional impact of metal sphere on thin metallic plate. The simulations are applied to different materials (Aluminum, Lead and Steel); however the target and projectile are formed of similar metals. A wide range of velocities (300, 1000, 2000, and 3100 m/s) are considered in this study. The goal is to study the most sensitive input parameters (impact velocity and plate thickness) on the longitudinal extension of the projectile, penetration depth and damage crater.

关键词： smoothed particle hydrodynamics high velocity impact sensitivity analysis

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Experimental study on velocity characteristics of recirculation zone in humid air non-premixed flame

GU Xin, ZANG Shusheng, GE Bing

《能源前沿（英文）》 2008年第2卷第2期页码 140-144 doi: 10.1007/s11708-008-0037-y

摘要： To examine the effect of the flow field within the recirculation zone on flame structure, the characteristic velocity fields of methane/humid air flame in non-premixed combustion behind a disc bluff-body burner were experimentally studied by particle image velocimeter (PIV).The results show that two stagnation points exist on the centerline in the recirculation zone flame. However, the distance of the two stagnation points in humid air combustion shortens, and the minimal dimensionless velocity increases compared with the conventional non-humid air combustion. In addition, the positional curves of the minimal velocities can be partitioned into three phases representing three different flame patterns. The analysis of axial minimal velocities on the centerline and their positions under different co-flow air velocity conditions reveals that fuel-to-air velocity ratio is the crucial parameter that governs humid air combustion flame characteristics.

关键词： distance bluff-body fuel-to-air velocity stagnation parameter

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圆形重力式网箱流场效应的试验研究

刘超,关长涛,崔勇,赵侠,李梦杰,李真真,王腾腾

《中国工程科学》 2014年第16卷第9期页码 69-77

摘要：

为探索圆形重力式网箱在动态流场中的水动力学特性，同时获得网箱系统内部与周围流场分布及流速变化规律，设计了4 种不同网目形状和不同网目大小的网箱模型（C1、C2、C3、C4），选取4 种不同水流流速（0.068 m/s、0.105 m/s、0.143 m/s、0.182 m/s），分别采用声学多普勒流速仪（ADV）和粒子图像测速（PIV）技术对网箱系统内外的流速及流场变化进行测定。结果表明，ADV试验与PIV技术测量结果基本一致；来流速度不同时，单个网箱范围内的水流衰减程度差异不大；来流速度相同时，小网目网箱的减流效果优于大网目网箱；网目大小相同时，菱形网目网箱减流效果优于方形网目网箱；群组网箱减流效果明显，且随着水流通过网箱数目的增加，网箱内与网箱后的流速降低明显，其中第2 个网箱中心的流速衰减率已经达到了67.6 %，第4 个网箱中心的流速衰减率为88.2 %，网箱后的流速衰减率为72.1 %。研究结果可为养殖生产实践中网箱类型的选择提供理论参考。

关键词：网箱 ADV PIV 流速流场分布

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definition of metabolic dysfunction-associated fatty liver disease with elevated brachial-ankle pulse wave velocity

《医学前沿（英文）》 2022年第16卷第5期页码 714-722 doi: 10.1007/s11684-021-0888-8

摘要： A new definition of metabolic dysfunction-associated fatty liver disease (MAFLD) has recently been proposed. We aim to examine the associations of MAFLD, particularly its discordance from non-alcoholic fatty liver disease (NAFLD), with the progression of elevated brachial-ankle pulse wave velocity (baPWV) and albuminuria in a community-based study sample in Shanghai, China. After 4.3 years of follow-up, 778 participants developed elevated baPWV and 499 developed albuminuria. In comparison with the non-MAFLD group, the multivariable adjusted odds ratio (OR) of MAFLD group for new-onset elevated baPWV was 1.25 (95% confidence interval (CI) 1.01–1.55) and 1.35 (95% CI 1.07–1.70) for albuminuria. Participants without NAFLD but diagnosed according to MAFLD definition were associated with higher risk of incident albuminuria (OR 1.77; 95% CI 1.07–2.94). Patients with MAFLD with high value of hepamet fibrosis score or poor-controlled diabetes had higher risk of elevated baPWV or albuminuria. In conclusion, MAFLD was associated with new-onset elevated baPWV and albuminuria independently of body mass index, waist circumference, and hip circumference. Individuals without NAFLD but diagnosed as MAFLD had high risk of albuminuria, supporting that MAFLD criteria would be practical for the evaluation of long-term risk of subclinical atherosclerosis among fatty liver patients.

关键词： metabolic dysfunction-associated fatty liver disease non-alcoholic fatty liver disease fibrosis score brachial-ankle pulse wave velocity albuminuria

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Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internal

Roham RAFIEE, Hossein RASHEDI, Shiva REZAEE

《结构与土木工程前沿（英文）》 2020年第14卷第6期页码 1349-1358 doi: 10.1007/s11709-020-0650-3

摘要： A theoretical solution is aimed to be developed in this research for predicting the failure in internally pressurized composite pressure vessels exposed to low-velocity impact. Both in-plane and out-of-plane failure modes are taken into account simultaneously and thus all components of the stress and strain fields are derived. For this purpose, layer-wise theory is employed in a composite cylinder under internal pressure and low-velocity impact. Obtained stress/strain components are fed into appropriate failure criteria for investigating the occurrence of failure. In case of experiencing any in-plane failure mode, the evolution of damage is modeled using progressive damage modeling in the context of continuum damage mechanics. Namely, mechanical properties of failed ply are degraded and stress analysis is performed on the updated status of the model. In the event of delamination occurrence, the solution is terminated. The obtained results are validated with available experimental observations in open literature. It is observed that the sequence of in-plane failure and delamination varies by increasing the impact energy.

关键词： composite pressure vessel low-velocity impact failure theoretical solution progressive damage modeling