Design and Structure Optimization of Plenum Chamber with Airfoil Baffle to Improve Its Outlet Velocity Uniformity in Heat Setting Machines

The plenum chamber of a heat setting machine is a key structure for distributing hot air to different air channels.Its outlet velocity uniformity directly determines the heating uniformity of textiles,significantly affecting the heat setting performance.In a traditional heat setting machine,the outlet airflow maldistribution of the plenum chamber still exists.In this study,a novel plenum chamber with an airfoil baffle was established to improve the uniformity of the velocity distribution at the outlet in a heat setting machine.The structural influence of the plenum chamber on the velocity distribution was investigated using a computational fluid dynamics program.It was found that a chamber with a smaller outlet partition thickness had a better outlet velocity uniformity.The structural optimization of the plenum chamber was conducted using the particle swarm optimization algorithm.The outlet partition thickness,the transverse distance and the longitudinal distance of the optimized plenum chamber were 20,686.2 and 274.6 mm,respectively.Experiments were carried out.The experimental and simulated results showed that the optimized plenum chamber with an airfoil baffle could improve the outlet velocity uniformity.The air outlet velocity uniformity index of the optimized plenum chamber with an airfoil baffle was 4.75%higher than that of the plenum chamber without an airfoil baffle and 5.98%higher than that of the conventional chamber with a square baffle in a commercial heat setting machine.

SIGNIFICANCE OF THE 6TH PLENUM OF THE 18TH CPC CENTRAL COMMITTEE TO THE WORLD

The 6th Plenary Session of the 18th CPC Central Committee was a very important meeting upon China’s entry into a decisive stage for completing the all-round construction of a moderately prosperous society,opening a new process of

China Society for Human Rights Studies Organizes Forum to Study and Implement Guidelines of 3rd Plenum of 18th CPC Central Committee

The China Society for Human Rights Studies （CSHRS） organized on Nov. 28 a forum to study and implement the guidelines of the third plenary session of the 18th Central Committee of the Communist Party of China （CPC）. Executive members of CSHRS and other CSHRS members in Beijing discussed improvement of judicial protection for human rights and legal construction in China. CSHRS President Luo Haocai, who was vice chairman of the 10th National Committee of the Chinese People＇s Political Consultative Conference, delivered a speech at the forum.

Third Plenum Points

THE new leadership in place in the Party since November last year and in their government positions as of March this year have spoken a great deal about the issue of urbanization. This plenum has given two ideas about how accelerated urbanization might occur. One is to address the household registration system,

A Novel Design of a Pre-separation Panel Structure to Protect Against the Impact of an Explosion in an Aircraft Plenum Chamber

To reduce the damage of the pressurizing panel structure of a fuselage caused by an explosion at the“least risk bomb location”in an aircraft structure,a new pre-separation panel structure was designed to resist blast loading.First,the dynamic strain response and morphology of impact damage of the new pre-separation panel were measured in an impact damage test.Second,the commercial software LS-DYNA was used to calculate the propagation of the blast shock wave,and the results were compared with empirical equations to verify the rationality of the numerical calculation method.Finally,the fluid–structure coupling method was used to calculate the damage process of the pre-separation panel structure under the impact of an explosion wave and an impact block.The calculated results were in good agreement with the test results,which showed the rationality of the calculation method and the model.The residual strength of the damaged pre-separation panel was significantly higher than that of the original damaged panel.The results show that the new pre-separation panel structure is reasonable and has certain significance for guiding the design of plenum chambers with strong resistance to implosion for aircraft fuselages.

加装谐振腔的巴哈赛车进气系统设计

为了提高赛车发动机的充气效率,进而提高发动机的性能,同时兼顾安全性,对小型越野巴哈赛车的进气系统进行了设计。首先依据波动效应计算进气管直径和长度;再依据发动机原机参数在GT-Power仿真软件中建立发动机原机模型,增设谐振腔,依据谐振腔对发动机有效功率的影响,选择出最佳谐振腔直径;最后设计进气口防水部件,使赛车具备较好的防水性能,以面对越野赛道恶劣的环境。

Effects of the plenum chamber volume and distributor geometry on fluidized bed hydrodynamics

Most hydrodynamic fluidized bed models, including CFD codes, neglect any effects of the plenum chamber volume. Experiments were performed in a 0.13 m ID fluidization column to determine plenum chamber volume effects on fluidized bed hydrodynamics for FCC and glass particles. Two low-pressure-drop distributors were used, one with a single orifice, and the other with 33 orifices and the same total open area as the single orifice. The results show two peaks in the frequency spectra for the single-orifice distributor, one representing bubble eruption at the bed surface and the other of higher frequency corresponding to the bubbling frequency at the distributor. The latter decreased slightly with increasing plenum volume and with increasing bed depth. For the multi-orifice distributor, broad frequency spectra from pressure measurements became narrower and moved towards higher frequency with decreasing plenum volume.

国家速滑馆防火复合型静压箱技术应用

在异形高大空间建筑中,采用结构复杂静压箱送风的工程并不多,也没有对静压箱的设计施工颁布相应的设计规范和施工标准,但静压箱设计的优劣直接决定静压箱周围的管线排布和相关房间的净高,以及舒适性和空气质量,因此有必要在实际工程中对静压箱的设计及施工情况进行研究。以国家速滑馆为例,研究异形结构部位静压箱的设计和施工,以满足该工程中对固定看台下方异形静压箱的技术参数要求,确保使用功能,方便施工。

CFD simulation of thermal hydraulic characteristics in a typical upper plenum of RPV

A comparative computational fluid dynamics(CFD)study was conducted on the three different types of pressurized water reactor(PWR)upper plenum,named TYPE 1(support columns(SCs)and control rod guide tubes(CRGTs)with two large windows),TYPE 2(SCs and CRGTs without windows),and TYPE 3(two parallel perforated barrel shells and CRGTs).First,three types of upper plenum geometry information were collected,simplified,and adopted into the BORA facility,which is a 1/5 scale system of the four-loop PWR reactor.Then,the geometry,including the upper half core,upper plenum region,and hot legs,was built using the Salome platform.After that,an unsteady calculation to simulate the reactor balance operation at hot full power scenario was performed.Finally,the differences of flowrate distribution at the core outlet and temperature distribution and transverse velocity inside the hot legs with different upper plenum internals were compared.The results suggest that TYPE 1 upper plenum internals cause the largest flowrate difference at the core outlet while TYPE 3 leads to the most even distributed flowrate.The distribution and evolution pattern of the tangential velocity inside hot legs is highly dependent on the upper plenum internals.Two counter-rotating swirls exist inside the TYPE 1 hot leg and only one swirl revolving around the hog leg axis exist inside the TYPE 2 hot leg.For TYPE 3,two swirls like that of TYPE 1 rotating around the hot leg axis significantly increase the temperature homogenization speed.This research provides meaningful guidelines for the future optimization and design of advanced PWR upper plenum internal structures.

Main Objectives and Tasks Set by the Plenum by 2020

the socialist democratic and legal system is further improved; the fundamental principle of administering the country according to law is implemented in an all-around way; people's rights and interests enjoy concrete respect and guarantees;

Parametric study on hydraulic performance of an inlet plenum in a printed-circuit heat exchanger

Hydraulic performance of an inlet plenum in a printed-circuit heat exchanger has been analyzed using three-dimensional Reynolds-Averaged Navier-Stokes equations. The numerical model of the inlet plenum was constructed through grid dependency test, calculation domain tests, and turbulence model and numerical scheme selections. Shear stress transport turbulence model was used for analysis of turbulence. Non-uniformity of the flow in zigzag flow channels was evaluated for the reference case. Parametric studies have been performed with the angle of the inlet plenum wall, radius of curvature of the inlet plenum wall, and width of the inlet pipes. The effects of these parameters on the flow uniformity and friction performance were evaluated.

可消毒静压箱板电极结构优化的数值模拟研究

疫情常态化管理时期对室内空气的及时净化成为了保障人们安全健康的重要工作。为解决这一问题,本文基于空调通风系统中的必要装置静压箱和消杀效果较好的基于热耦合电晕放电技术的空气消毒装置,研究出了一款可消毒静压箱,能够实现空调系统兼具通风和消毒的功能。本文运用CFD技术,针对消毒装置阵列板电极的不同板数、板型及尺寸,对可消毒静压箱的稳压消毒综合效果进行了评估,并给出了可消毒静压箱的优化设计方案。结果表明,当消毒装置的阵列板电极板数为6,板型为1/4圆形,板宽为114 mm时,其应用于可消毒静压箱时的消毒和通风综合效果最优。

数据中心静压箱优化措施综述

我国数据中心数量大、增长速度快,每年有大量的能源用于数据中心的制冷系统,数据中心的热管理面临巨大挑战。为有效降低数据中心制冷系统能耗,需要对数据中心的气流组织进行管理。地板送风已成为目前应用最广泛的数据中心送风方案,静压箱是影响地板送风系统气流分布的关键结构。介绍了数据中心气流组织的常用研究方法;总结了静压箱设计过程中的优化方式,包括静压箱深度调节、开孔率调节、障碍物排布规律调节;概括针对在运行数据中心静压箱的辅助设施优化方案,包括辅助隔板和辅助风机,可为数据中心静压箱的设计及优化提供参考。

新型逆流式露点蒸发冷却器热质交换性能的 数值模拟研究

为了改善逆流式露点蒸发冷却器内部空气流动的不均匀性,在已有冷却器下方增设静压箱和均流装置。通过建立逆流式露点蒸发冷却器的二维模型,对其热湿传递过程进行数值模拟计算,对比改进前后冷却器的速度和温度分布情况,进一步研究入口风速、二次/一次风量比、通道长度对其热质交换性能的影响。结果表明:改进后逆流式露点蒸发冷却器内一次空气速度不均匀度的变化范围为0.07~0.14,其值约为改进前冷却器的1/10,说明改进后冷却器内的一次空气速度场分布较均匀,热湿交换空间充分得到利用,从而提高冷却效率;另外,当入口风速为2~3 m/s,二次/一次风量比为0.25~0.4,通道长度为1 m时,冷却器的湿球效率在115%以上,冷却性能更佳。

秦山核电站二期反应堆堆芯流量分配数值分析

获得可靠的堆芯入口流量分配数据是改善压水堆堆芯热工水力性能的需要。应用计算流体力学方法研究了反应堆压力壳内复杂的流动现象,得到了秦山核电站二期600 MW反应堆1/4整体水力模型的堆芯入口流量分配状况,并对下腔室几何结构、冷管段入口流量等影响因素进行了敏感性研究。分析结果表明,双环路工况入口流量对堆芯入口流量分配影响较小;与双环路工况相比,单环路运行工况时流动特性显著变化,导致流量分配状况差异较大;堆芯入口流量再分配因子为0.05,与原型设计参数吻合。计算结果证实所采用研究方法有效,可为相关反应堆工程设计验证提供依据。

跨声速压气机实验系统Helmholtz频率的影响因素及估算方法研究

针对压气机实验系统Helmholtz共振频率的研究对于建设压气机试验系统及研究压气机流动不稳定现象均有重要意义。以北京航空航天大学跨声速压气机试验系统为背景,通过拆除该压气机试验系统的稳压箱、格栅等部件以及更改该试验系统的几何尺寸,分析该型压气机试验系统Helmholtz共振频率的影响因素;同时引入了Duct-Compressor-Plenum模型理论,对该压气机试验系统进行相应的模化,并对其系统Helmholtz共振频率进行相应估算。结果表明:在该类型的跨声速压气机试验系统中,压气机前端的稳压箱及稳压箱之前部分主要作用是为整个试验系统提供均匀的进气环境,而对系统Helmholtz共振频率不产生任何影响。因此,在跨声速压气机试验系统Duct-Compressor-Plenum模型模化过程中,不应将稳压箱及其之前部件进行模化。

反应堆压力容器下腔室交混特性的数值模拟方法研究

反应堆冷却剂系统蒸汽管道发生破口事故后,硼溶液在反应堆压力容器下腔室的对流交混特性对于反应堆安全分析及事故后缓解与抑制策略制定均有重要作用。本文基于实验结果分析了反应堆压力容器下腔室的交混特性及浓度扩散过程,采用数值模拟方法结合实验数据比较了几种主要模型计算结果的准确性与可靠性。分析结果表明,压力容器下腔室的交混特性呈现出外围扩散特征,温度梯度法与组分输运模型具备描述浓度梯度扩散过程的能力,但在细节分布上仍存在进一步改善与优化的空间。

上空腔小破口失水事故模拟实验

文中给出了位于上空腔的中小尺寸接管破裂或安全阀意外开启引起的小破口失水事故的模拟实验研究情况。在实验中研究了系统压力,温度、空泡份额的变化和总失水量。总失水量约为初始装水量的20%。

图书馆绿色发展的理论要义与实践路径

"绿色·低碳"是可持续发展的核心要义,图书馆作为公共文化服务的重要主体,理应成为绿色发展的引领者和践行者。文章重点分析三维复合系统中图书馆绿色发展理念,回答图书馆为什么要贯彻绿色发展理念以及怎样贯彻这一理念等两大问题,为推进图书馆的绿色发展与经济、社会和环境三维复合系统的可持续发展提供理论与实践指导。