共查询到19条相似文献,搜索用时 109 毫秒
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刘燚刘贝贝张忠立林正皓蒋厚庸周宇仁 《真空科学与技术学报》2023,(11):931-937
针对同类通道型正压标准漏孔在不同工况下漏率的机理问题,将多孔泡沫金属填充于通道型正压标准漏孔中并建立数学模型。采用数值模拟的方法分别分析了不同工况条件下对通道型正压标准漏孔漏率的影响,同时给出泡沫金属内部速度场分布。结果表明,在恒定的气源压力下,与Air、He以及D2相比,H2获得的漏率最大;漏孔的漏率随气源压力的增大而增大;对于恒定的孔径或孔隙率条件下,通道型正压标准漏孔的漏率随着孔径或孔隙率的增大而增大,随通道型正压标准漏孔长度的增加而降低;非线性变化孔隙率能够有效改善并控制漏率的大小。该项研究对正压标准漏孔的生产和发展、计量方面的检漏工作,以及控制漏率来优化和设计密封系统性能方面提供了有价值的参考意义。 相似文献
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《真空科学与技术学报》2017,(12)
真空标准漏孔作为标定检漏仪或被测量漏率的参考标准,在核工业、航天航空等领域得到了广泛应用。本文利用氦质谱检漏仪和定容法对标准漏孔(铭牌漏率:2.3×10-6Pa·m3/s,He,23℃)进行校准,以为快速地定量研究聚变材料中氘(D2)或氦(He)行为提供有用的参考。研究结果表明,漏孔漏率随入口端气体压强的增大而增大,并与漏孔两端气体介质压强的平方差呈线性递增关系。同一入口压强下,D2的漏率高于He,且漏率之间的差异随压强增加而变大。同一条件下,定容法和氦质谱检漏仪测得漏孔中示漏气体He的漏率值基本相等,但示漏气体为D2时,氦质谱检漏仪测得的漏率值高于定容法。研究还给出了氦质谱检漏仪测量示漏气体D2时漏孔漏率的修正关系式。 相似文献
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《真空科学与技术学报》2017,(12)
为满足大型氦气工程试验回路(Helium Test Loop,HTL)工作状态下泄漏率的精确定量要求,进行了模拟刚性高压标准漏孔的研制工作。采用石英玻璃钻孔法制作得到正压漏孔2支,测定了漏孔在入口压力为0.7~7.0 MPa(表压),出口为大气压(绝对压力100 k Pa)和真空(绝对压力10 Pa)两种情况下的泄漏率,并且采用圆导管模型模拟了2支漏孔在不同压力范围下泄漏率与压力之间的关系,发现He气通过两支漏孔的泄漏为粘滞-分子流状态,漏率与压差之间的关系可以采用二次多项式进行拟合,拟合相关性系数良好。研究结论很好的揭示了刚性漏孔在较高压力下的泄漏状态,并且为正压检漏在相对较高压力范围内(0~7 MPa)的应用提供了良好的校准工具。 相似文献
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为了寻找一种简易的正压漏孔校准手段,试制了一个充液式U形毛细管漏孔校准装置,并对不同漏率的正压漏孔进行了大量的实验。通过对实验数据进行分析,对校准过程中产生的测量不确定度进行了分析和评定,得到了一种简易可行的校准正压漏孔的方法。 相似文献
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《真空科学与技术学报》2018,(12)
为了解决漏率小于10~(-8)Pa·m~3/s正压漏孔(示漏气体为He气)的校准问题,研制出下限可达10~(-10)Pa·m~3/s的校准装置。提出基于累积比较的正压漏孔校准方法,通过向漏孔入口充入100 kPa高纯度N_2气模拟大气压环境,将漏孔泄漏后的示漏气体引入累积室经过一段时间的累积来提高浓度,采用膨胀衰减压力和分子流进样将混合气体引入质谱分析室,提出对质谱分析室中示漏气体进行累积模式的测量方法,通过四极质谱计作为比较器分别测量漏孔泄漏形成的混合气及配置的标准混合气体在累积模式下离子流的变化率得到漏孔漏率,解决了无法测量微小示漏气体离子流信号的技术瓶颈;采用全金属密封结构和特殊的工艺处理解决了累积室中延伸下限由于本底示漏气体的影响因素,采用体积小于1 mL的取样室通过直接取样和膨胀衰减压力取样获得与漏孔累积后形成同等数量的标准混合气体,解决了微小漏率正压漏孔校准所用标准混合气体获得。为此基于累积比较法的正压漏孔校准方法实现了10~(-8)~10~(-10)Pa·m~3/s的校准范围,合成标准不确定度不超过7. 5%。 相似文献
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W. Jitschin 《真空研究与实践》2003,15(4):188-193
In the testing of leak tightness and in the localisation of leaks by means of a test gas, proper operation and sensitivity of the employed instrument must be checked by a certified reference leak. In the so‐called sniffer mode of operation, the component under test is filled to overpressure with the test gas, so that in case of a leak there is a gas flow from the component to atmosphere. The atmospheric gas is sucked by the instrument and probed for its test gas content. For checking the instruments performance, commercial test leaks are available for various gas species, which deliver a well‐defined leakage. Construction and properties of such a test leak are described. The leak has an internal gas reservoir and a capillary as leak element. Because the inlet pressure at the capillary is kept constant by a pressure controller, the leakage remains constant over several years despite the gradual pressure decrease in the gas reservoir. The calibration of the leakage via the volume flow rate is described in detail. The volume flow rate can be measured by a liquid drop in a measuring capillary as well as a displacement piston in a dosing syringe. 相似文献
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ABSTRACT In pressure vessels and piping the leak‐before‐break (LBB) assessment method is employed to avoid any catastrophic failure prior to a detectable leakage. One of the most important parameter, the leak rate, is investigated in the present paper by means of the Monte Carlo method. A brief review is carried out with emphasis on aspects such as crack growth, crack size with detectable leakage, crack opening area and leak rate. Issues concerning the property and behaviour of multiple cracks are also covered along with a review of the characteristics of leak rate through distributed multiple cracks using a statistical simulation method. The simulation results show that the effect of multiple cracks is quite significant to the LBB concept. Both the relationship between leak rate and crack length (or time) and the statistical characteristics of the leak rate are considerably different for different initial crack conditions. 相似文献
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工业上一般使用标准漏孔对冷媒检漏仪进行定性检测,由于它的便捷性而得到广泛使用。近年来,对标准漏孔的溯源方式和校准方法进行探索逐渐进入人们的视野,冷媒气体泄漏率的定量分析和测量过程的不确定度评估定量分析就显得尤为重要。通过建立数学模型,对标准漏孔在测量过程中影响测量不确定度的因素进行分析和量化。最后通过实验验证,测量结果的相对扩展不确定度约为4%,可以满足了泄漏率量值传递过程中10%的要求。 相似文献
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Wolfgang Jitschin 《真空研究与实践》2002,14(2):97-102
In order to perform reliable quantitative measurements of leak rates, the used leak detection equipment is calibrated by injection of a known leakage flow delivered by a test leak. Well‐proven are Helium test leaks of the diffusion type with internal gas reservoir. The present paper deals with the construction of such leaks, the temperature dependence and response time of the leak rate, and their calibration. In case of careful handling, the relative uncertainty of the delivered leakage flow can amount to only 3 % (2σ). 相似文献
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Lan Zhao Yongjun Cheng Wenjun Sun Yongjun Wang Lian Chen Xuemin Sheng Ruifang Zhang Meiru Guo Yanwu Li 《Mapan》2018,33(2):91-97
The leak rate of spacecraft port must meet certain standards during the opening and closing processes. The port quick leak detector can be used to on-line measure leak rates of spacecraft port. In this work, a new calibration apparatus is designed and investigated. It can work at different temperatures with different gases in a wide leak rate range. This apparatus consists of the standard leak rate system, calibration system, temperature control system, gas supply and pumping system, which is designed on the basis of direct comparison calibration method and pressure-rising method with a constant volume, and the leak rates are provided by the standard leak rate system. The calibration range of the calibration apparatus is from 2 × 10 –6 to 2 × 10 –2 Pa m3/s. Its combined standard uncertainty is about 4.7%, and its calibration temperature is from ? 50 to 20 °C. Within the above leak rate and temperature ranges, the correction factor of the port quick leak detector is about 0.88–1.09. 相似文献