空间用FM08系列熔断器漏率研究与仿真分析

为保证空间用FM08系列熔断器在规定的任务时间内不因密封原因失效,必须制定合理的漏率指标。本文从漏孔的气流特性出发,研究并建立了FM08系列熔断器真空泄漏数值模型。在此基础上,对允许漏率、气体压力等进行了数值仿真分析,得出了不同任务周期下FM08允许漏率指标,该结果与NASA研究结果基本一致,验证了仿真模型的正确性。本文研究结果对航天工程确定FM08系列熔断器的密封性要求具有实际指导作用。     

基于不同气体和压力下通道型正压标准漏孔漏率的分析

依据JJF 1627-2017《皂膜流量计标准漏孔校准规范》以及正压标准漏孔校准装置,分别分析了在高纯空气、高纯氮气、高纯氦气和不同压力条件下对漏孔漏率的影响。研究结果表明,同种气体在较小的压力下,漏孔中的漏率与压力成比例关系。此外,同种气体通过漏孔的漏率会随进口压力的增大而增大,在进口端压力相同且压力较大的条件下,高纯氦气的漏率值最大,这说明气体分子的黏滞性是影响漏率大小的主要因素。     

温度变化对漏孔漏率的影响

分析了漏孔在温度夹变时漏孔的热物理过程和与之相适应的漏孔漏率变化。认为漏孔在突然处于低温状态时，漏率变化的主要因素是示漏气体滞粘系数随温度的变化而造成，漏孔尺寸随温度变化引起漏率变化是次要的。在非稳定状态时，漏率随时间呈指数式变化。     

大型真空系统氦检漏率的快速准确检测方法

大型真空系统检漏往往耗时长、效率低。本文分析了氦气通过漏孔进入氦质谱检漏仪形成检漏信号的规律,并据此建立检漏信号数学模型,确定漏孔的最终稳态泄漏信号。基于上述分析,提出漏孔漏率的一种快速预测方法。该方法用于大型真空系统检漏能准确预测被检部位的漏率,能显著缩短检漏时间,提高检漏效率。     

正压漏孔校准装置

正压漏孔校准装置是校准气体漏率的计量标准,可采用定容法和定量气体动态比较法对正压漏孔进行校准,校准范围为1×10     

德国联邦物理技术研究院（PTB）气体微流量计量评介

在真空技术应用中，高精度气体微流量计用于连续膨胀法校准系统压力的产生、漏孔漏率的测量以及真空泵抽速的测定。FIB先后研制了三代气体微流量计，第一代为手动型，第二代为半自动型，第三代为全自动型。本详细介绍了FIB研制的气体微流量计的性能和特点，并介绍了气体微流量计在真空漏孔的漏率测量方面的应用。另外，还介绍了FIB最近研制的大气压力下漏孔漏率测量系统的性能和特点。     

德国联邦物理技术研究院(PTB)气体微流量计量评介

在真空技术应用中 ,高精度气体微流量计用于连续膨胀法校准系统压力的产生、漏孔漏率的测量以及真空泵抽速的测定。PTB先后研制了三代气体微流量计 ,第一代为手动型 ,第二代为半自动型 ,第三代为全自动型。本文详细介绍了PTB研制的气体微流量计的性能和特点 ,并介绍了气体微流量计在真空漏孔的漏率测量方面的应用。另外 ,还介绍了PTB最近研制的大气压力下漏孔漏率测量系统的性能和特点     

温度对薄膜渗氦型漏孔漏率的影响研究

介绍了气体微流量标准装置对漏率的校准方法.在温度16～50℃范围内,对两支薄膜渗氦型漏孔进行了校准,并给出了温度与漏率的关系表达式.得出了研究结论.     

金属压扁型正压漏孔不同压力下的漏率研究

在不同入口和出口压力条件下,正压漏孔的漏率值会发生变化,在使用时需要对正压漏孔的校准值进行修正。对2支金属压扁型正压漏孔在多种压力条件下进行漏率测量,给出了测量结果,然后根据管道流导理论推导出正压漏孔漏率随压力变化的修正公式,并对修正结果与实验测量数据进行了研究分析。     

气体稀薄流域的流动模型研究

研究气体通过漏孔的泄漏过程,建立气体在稀薄领域里的统一流动模型,可以避免对流态判断的困难,方便工程应用.气体稀薄流域的统一模型适用于从粘滞流到分子流的全部流态的数学模型.从N-S方程出发,利用滑移边界条件以及修正黏度推出统一流动模型,进而建立漏孔漏率与压力边界之间的关系式,引出稀薄气体流域下的经验公式,并通过试验可确定其待定系数.而且利用四极质谱法和压升法试验验证了模型的使用性及正确性,为今后的研究应用提供了参考依据.     

A probabilistic simulation of fluid leakage in multiple cracks situation

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.     

Prüflecks für Schnüffel‐Lecksucher

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.     

低温绝热容器氦质谱检漏方法探讨

漏率是低温绝热容器产品的主要技术参数之一,利用氦质谱检漏技术对漏孔进行定位、定量检测可以起到控制产品质量的目的。文章首先对低温绝热容器用两种氦质谱检漏系统进行了比较和试验分析。结果表明：在测试条件一致的情况下,标准漏孔安装在系统中的不同位置,将对系统最小可检漏率、系统反应时间、漏率测算值产生影响。在对影响结果进行分析的基础上,对实际检漏工作提出相应建议。其次对分流和无分流两种检漏方法的选择原则进行了探讨。然后以53m^3液化天然气储运容器为例,对容器制造过程中的角焊缝、对接焊缝、夹层内存在的漏孔、阀门及容器整体的检漏方法进行了详述。最后对检漏过程中应注意的事项进行了说明。     

Helium‐Testlecks zur Kalibrierung von Lecksuchern

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).     

冷媒气体泄漏率的定量分析

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。     

Helium‐Testlecks

Helium test leaks Leak localization and tightness control with Helium provides a very sensitive testing method. Frequently, the sensitivity of a leak has to be testspecified quantitatively. In particular, quality control requires a reliable verification of the sensitivity. For this purpose, test leaks with well‐known leakage are used. In the article, various types of test leaks and their properties are described. Test leaks are commercially available over a wide range of leak rates. Their leakage flow can be calibrated with good accuracy. In the usage of the test leaks, the temperature‐dependency of the leak rate has to be taken into account, as well as the slow decrease of the leak rate due to the continuous loss of gas from the reservoir.     

Investigation of leak detection method by means of measuring the pressure increment in vacuum

Leak detection by measuring the pressure increment in a vacuum has found wide application on pressure vessels, pipes and accessories. However, the reproducibility of the method and the effect of some secondary factors on the results of leak detection have not yet been satisfactorily studied and explained. In this paper, the leak detection method is discussed and the possibility of measuring small leakage rates outlined. Some factors influencing the results, especially the virtual leakage rate and test temperature, which may affect the accurate measurement of small leakage rates, are investigated in detail. In order to improve measurement accuracy, it is suggested that the evacuation time is prolonged and, if possible, the testing system is pre-heated, to eliminate the influence of the virtual leakage rate as far as possible. The research results indicate that both the variation of the ambient temperature and the inconsistency of the temperature of the testing system with that of the gas leaking into the system will introduce errors. Methods for correcting measured results are proposed.