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航空发动机试验中通常使用钟形口流量管对进气流量进行试验。在测量过程中,针对测点布置不准确造成测量结果不准确及测量成本增加的问题,开展了管内入口段测量截面上的速度分布情况研究。本文分析了钟形口流量管的测量原理以及湍流状态下管内气流的流动状态,研究了测量截面沿直径方向上速度的变化,建立了管内径向速度分布的数学模型,最终通过试验与仿真的方法对速度分布模型进行了分析与验证,为准确得到管内空气流量提供了一种基于速度分布模型的新方法,即通过试验测得流量管测量截面上少数点的数据信息得到管内速度分布模型,从而得到更准确的管内空气流量值。研究结果对进气流量的测量以及发动机性能的评定试验有重要意义。 相似文献
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本文利用热式空气流量传感器直接测量空气质量流量的特点 ,设计了一种广泛应用于测量电控发动机进气质量流量的热式空气流量传感器。介绍了热式空气流量传感器的基本原理、工作电路 ,并就其温度补偿进行了研究。 相似文献
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工业蒸汽的热能计量需要解决干度测量和热能相关量值溯源等计量基础问题.在本文中,研究了焓流量计量标准蒸汽源.阐述了蒸汽焓流量的计量方法,基于热力学建立了蒸汽源焓流量与干度等参数量值确定的理论模型.介绍了焓流量计量标准实验装置的组成、对过热蒸汽加湿以获得湿蒸汽的设计方案和温度、压力、流量参数的测量方法.本装置可在DN50和DN80管路提供0.3~0.9 MPa、7~70 m/s的过热蒸汽流和0.85~1.00干度的饱和蒸气流,并能确定蒸汽源的干度、质量流量和体积流量、焓流量等量值,焓流量、干度和流量稳定性分别优于2%、0.5%和2%,扩展不确定度分别为0.8%、1%和0.5%.对实验装置性能和实验结果进行了讨论.该装置可用于蒸汽热能计量仪表的模型研究和性能试验. 相似文献
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水大流量标准装置是负责开展大口径流量仪表测试、确保大流量量值溯源与传递准确可靠的核心设备,而测控系统是流量标准装置的重要组成部分。目前国内专门针对水大流量装置控制系统的研究开展较少,已有的研究成果已远远滞后于水大流量计量技术现状,且难以满足社会对大口径流量仪表自动化、智能化、高准确度的检定校准需求,而这些问题的存在又反过来对流量标准装置的进一步推广和应用造成了制约。设计并开发了一套适用于水大流量标准装置的控制系统,并通过稳定性和流量调节响应时间这两个性能指标对系统性能水平进行了评价,测试结果表明:管路流量处于480~7 800 m3/h范围内的系统稳定性Eq=0.193%<0.2%、流量从0提升至8 500 m3/h的稳定流量对应的系统响应时间约为110 s,其性能水平较为出色。 相似文献
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为提高大口径管道流量在线校准的准确度,建立了一套多声道超声测流装置,对其现场探头定位安装及几何测量方法进行了优化,并在研究流量计算模型的基础上进行了不同探头插入状态的实验室测试。在DN400的管道上安装交叉4声道超声探头,测试了3种探头插入状态,通过分析流量测量误差来得到最优化方案。实验表明,探头插入状态显著影响装置流量测量误差,随着插入深度的增加流量测量结果逐渐增大,但即使全突状态流量依然偏小;3种状态中全缩线性较好,经过系数修正后,全缩状态下超声测流装置计量准确性最高,达到0.2级;超声测流装置经过实验室测试与优化,可以满足1.0级大口径管道流量在线校准的要求。 相似文献
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新结构RH真空脱气装置水模型实验观察 总被引:2,自引:0,他引:2
为了延长RH真空脱气装置的寿命,同时增加RH系统的精炼效率,本文设计了一种RH真空循环脱气装置的新结构。使用水模型实验分析了新结构装置的环流特性,并同传统结构的RH真空脱气装置的环流特性进行了比较分析。利用碳黑墨水染色法分析系统内钢包的混合能力。结果表明:(1)当吹入相同的气体量(Q=1.5)时,新装置中的水模型中碳黑墨水的扩散速度比传统装置中水的扩散速度快约1/3。(2)传统装置有一个上升管,而新装置中有三个上升管,当传统装置和新装置吹入相同的气体流量时,传统装置中的上升管管内体积被气体占据的多,影响水的循环运动。(3)当吹入相同的气体量时,新装置的液体循环流量比传统装置中的循环流量大,并随着喷入气体量的增加,新装置的循环流量增加也比传统装置增加的大。 相似文献
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汽车发动机进气流量测量是发动机台架测试的重要项目,其测量结果直接影响排放的结果.文章制定了一种针对汽车发动机台架测试流量计计量性能监控的方案.该方案研制了专门的核查和修正装置,通过内部核查、外部检定和二次修正相结合的方式,对流量计的计量性能实施监控.当流量计的计量性能出现偏离时,通过二次修正模块对流量计进行修正,使其满... 相似文献
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《中国工程学刊》2012,35(1):115-128
Most classrooms of Thai state primary schools are designed to use cross-flow natural ventilation as a passive cooling system. The aim of this study is to investigate the effects of geometry and orientation of school buildings to indoor airflow distribution and thermal comfort in typical state school classrooms. Computational fluid dynamics commercial software was used as a tool in this simulation. Local meteorological conditions and measured data at a real building were employed as the boundary conditions. The airflow simulation for building domains was performed with reference to the prevailing wind. Wind speeds and directions close to openings were averaged and used to represent the inlet boundary conditions of the classroom domains. Manikins and desks were included in the classroom domains. The simulation was carried out, focusing on a comfortable indoor thermal environment for the occupants. Simulated results revealed that an orientation of a school building normal to wind direction might not always be necessary to obtain a thermally comfortable environment in a classroom. Main inlet flow from openings was not found to affect the students directly. However, a comfortable feeling was possible within the occupied zone in winter when ambient temperature was low. Operative temperatures were also within 90% acceptability limits, according to the adaptive comfort standard. 相似文献
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程控机房下送风空调设计的问题及措施 总被引:3,自引:1,他引:2
分析了电信程控机房对室内环境的要求,叙述了电信程控机房应用下送风空调的主要优点,分析了它使用不当易出现的局部送风断面堵塞、气流短路、机柜和楼板结露、楼板的防火和保温处理及架空地板下局部区域积尘等问题,并给出了相应的应对措施,可供有关设计、施工及管理人员参考。 相似文献
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以某型号柜机为研究对象,采用CFD模拟技术对柜机室内机的风道系统进行三维数值模拟,通过分析风道的气流组织情况、改进原机多翼离心风机扩压口的型线、优化风道内部流场达到增大整机循环风量的目的。数值模拟结果显示,改进后的风机的风量比原机的增大5.1%。根据数值模拟结果制作手板进行实验验证,通风量由1 145 m3/h增加到1 199 m^3/h,增幅为4.7%,实验结果与数值模拟结果具有较好的一致性。 相似文献
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Haomin Wang Shuo Li Yiliang Wang Huimin Wang Xinyi Shen Mingchao Zhang Haojie Lu Maoshuai He Yingying Zhang 《Advanced materials (Deerfield Beach, Fla.)》2020,32(11):1908214
Recently, electronic skin and smart textiles have attracted considerable attention. Flexible sensors, as a kind of indispensable components of flexible electronics, have been extensively studied. However, wearable airflow sensors capable of monitoring the environment airflow in real time are rarely reported. Herein, by mimicking the spider's fluff, an ultrasensitive and flexible all-textile airflow sensor based on fabric with in situ grown carbon nanotubes (CNTs) is developed. The fabric decorated with fluffy-like CNTs possesses exceptionally large contact area, endowing the airflow sensor with superior properties including ultralow detection limit (≈0.05 m s−1), multiangle airflow differential response (0°–90°), and fast response time (≈1.3 s). Besides, the fluffy fabric airflow sensor can be combined with a pristine fabric airflow sensor to realize highly sensitive detection in a wide airflow range (0.05–7.0 m s−1). Its potential applications including transmitting information according to Morse code by blowing the sensors, monitoring increasing and decreasing airflow velocity, and alerting blind people walking outside about potential hazard induced by nearby fast-moving objects are demonstrated. Furthermore, the airflow sensor can be directly integrated into clothing as stylish designs without sacrificing comfortness. It is believed that the ultrasensitive all-textile airflow sensor holds great promise for applications in smart textiles and wearable electronics. 相似文献
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体育馆类高大空间的气流组织设计难点及对策 总被引:9,自引:0,他引:9
文中讨论了体育馆类高大空间气流组织的主要形式及设计难点,并从工程应用的角度给出了相应对策;指出用计算流体动力学(CFD)的方法进行体育馆类高大空间的气流组织设计具有很大优势,并提出了利用CFD进行高大空间气流组织设计的思路。 相似文献
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By revisiting the air distribution and bioaerosol dispersion in Ward 8A where the largest nosocomial severe acute respiratory syndrome (SARS) outbreak occurred in Hong Kong in 2003, we found an interesting phenomenon. Although all the cubicles were in ‘positive pressure’ towards the corridor, the virus-containing bioaerosols generated from the index patient''s cubicle were still transmitted to other cubicles, which cannot be explained in a traditional manner. A multi-zone model combining the two-way airflow effect was used to analyse this phenomenon. The multi-zone airflow model was evaluated by our experimental data. Comparing with the previous computational fluid dynamic simulation results, we found that the air exchange owing to the small temperature differences between cubicles played a major role in SARS transmission. Additionally, the validated multi-zone model combining the two-way airflow effect could simulate the pollutant transport with reasonable accuracy but much less computational time. A probable improvement in general ward design was also proposed. 相似文献
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一般采用气体流量计前加装缓冲器消除压缩机性能试验装置中气流脉动对测量精度的影响。本文分析2种适用于大型活塞式压缩机性能试验装置的缓冲器容积的计算方法,认为针对压缩机性能试验装置中的微小脉动气流,德国BORSIG的计算方法更加适合。搭建大型活塞式压缩机性能试验装置,利用经理论计算设计的缓冲器进行试验,发现即使在最大测试流量的情况下,缓冲器仍然可以很好地削减气流脉动的影响,从而大大提高压缩机试验装置的试验精度。 相似文献