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微波谐振腔蒸汽湿度测量系统不确定度分析 总被引:1,自引:1,他引:0
推导了微波谐振腔蒸汽湿度测量关系式的灵敏度系数;分析了压力和频率等直接测量参数的不确定度;以不同压力及湿度的湿蒸汽为例,分析湿度测量关系式中各计算参数的不确定度,合成了蒸汽湿度测量系统的标准不确定度,分析了蒸汽压力和湿度变化对系统不确定度的影响;确定了考虑参数测量、腔体热膨胀、取样误差、腔体内壁沉积水膜等因素时系统的综合不确定度.结果表明:系统综合不确定度uz≤0.764%;随着蒸汽湿度和压力值的增大,蒸汽湿度测量系统的合成标准不确定度变大;系统压力测量引入的不确定度较小,可以忽略,而频率测量引入的不确定度较大,谐振频率的准确测量是确保系统测量精度的关键. 相似文献
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建立了加热法测量湿度探针进口附近区域流场的数学模型,并通过对其进行数值模拟来分析由于非等动能取样及汽流方向偏离轴线所造成的测量误差,从而为加热法测湿探针的设计及其在工程中的运用提供依据。 相似文献
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微波谐振腔法测量蒸汽湿度时,由于液滴的沉积在谐振腔内壁会形成一层水膜。分析了沉积水膜在腔内的分布及水膜对测量结果的影响。结果表明:在水膜较薄时,其对测量结果的影响非常小,随着水膜厚度的增大其影响明显增加。用于汽轮机排汽湿度测量时,谐振腔内壁水膜厚度不到10μm,忽略水膜影响引起的测量误差只有0.1%。图4表1参8 相似文献
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蒸汽中含有过多的杂质,会引起过热器受热面、汽轮机流通部分和蒸汽管道沉积盐垢,对锅炉、汽机和阀门造成严重影响。蒸汽取样装置是蒸汽取样的主要设备之一,在锅炉运行中,通过取样可对蒸汽进行严格化学监督起到重要作用。介绍几种蒸汽取样装置及设计改进,为蒸汽取样装置的优化设计提供参考。 相似文献
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为探明扇贝阻尼密封在不同阻塞状态下的静态稳定性,应用计算流体力学方法研究阻塞、非阻塞工况对扇贝阻尼密封静态刚度与气流力的影响规律。研究表明:阻塞工况下,不同错开角及中高长径比下密封气流力、静态刚度均随偏心率增加而降低,低长径比密封气流力在高偏心下较大;非阻塞工况下,不同错开角、长径比的密封气流力随偏心率增加而增大,高偏心率下静态刚度较小,非阻塞工况密封静态稳定性高于阻塞工况;由于进出口压差存在,使得扇贝阻尼密封马赫数在进出口两端增长较大,非阻塞状态进出口段马赫数变化幅度小于阻塞状态。 相似文献
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IntroductionThe final stages of large steam turbines in fossilpower plant and all stages of turbines in nuclear powerp1ants operate in the wet steam region. It is important todevelop a simple direct method for measuring thewetness of flowing wet steam. The heating method hasmany advantages. First, compared with optical method,the measured wetness results of this method consist ofevery size of water droplets in wet steam flow. Second, itis not restricted to the measurement environment, it canb… 相似文献
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本文应用商业CFD软件Fluent对某型汽轮机速关阀不同阀开度下的二维流场特征进行了数值模拟,给出了通流部分流场的总压、流线及马赫数的分布情况.数值模拟结果表明,在大开度情况下,阀体内部马赫数较低,损失较小;开度较小时阀座与阀碟之间的喉部将出现激波和超音流动,从而带来较大的损失. 相似文献
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《International Journal of Hydrogen Energy》2019,44(31):16718-16734
The present study discusses the effects of reacting and non-reacting flow conditions on the flow physics of a scramjet combustor. A cavity based supersonic combustor with a triangular strut is used to analyze the mixing behavior of fuels namely, hydrogen and ethylene, numerically. In this context, the influence of Mach number on static pressure distribution, mixing efficiency and the mole fraction of hydrogen and ethylene is analyzed. Our study reveals that there is a strong interplay between flow conditions viz., reacting and non-reacting and Mach number on flow field characteristics. It has been observed that the ignition delay time is very less for hydrogen fuel as compared to ethylene fuel. Further, the mixing efficiency is found to be maximum at Mach 2.5 and Mach 3.5 for hydrogen and ethylene, respectively for reacting flow conditions. Moreover, it was observed that additional igniters are required to enhance the rate of mixing in case of ethylene since the complete mixing of ethylene and air occurs at higher Mach number. It is seen that the deviation in the static pressure and mixing efficiency for reacting and non-reacting flow increases with the increase in Mach number. Further, this deviation is found relatively higher for hydrogen as compared to ethylene. 相似文献
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汽轮机超临界级变工况热力计算方法的改进 总被引:9,自引:3,他引:6
针对汽轮机超临界级变工况计算过程中存在的马赫数>M与M<1交替发生而使计算不收敛的问题,分析了其产生的原因,提出了有效的改进办法。 相似文献