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正弦压力参数的准确计算是评价正弦压力发生器技术指标和用正弦压力发生器校准传感器的基础。本文提出了一种在非整周期条件下准确计算正弦压力参数的方法。与其它方法相比,该方法采用时,频域结合的方式,具有计算结果可靠,计算精度高的优点。 相似文献
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根据压力传感器动态性能校准和应用校准的特点,对现有主要动态压力校准方法,如激波管法、快开阀法、落锤和气动冲击法及连续正弦压力发生器法的适用性进行分析,上述方法多数属于压力传感器动态性能校准,且主要是定性校准,不是定量校准,多数不适合应用校准。本文对两种新技术,平台压力发生器法和离散式正弦压力发生器法的性能作出评估,指出平台压力发生器法是理想的瞬态压力校准法,能直接给出压力动静比随频率的变化量,它不需要参改传感器,它是应用校准的理想方法。离散式正弦压力发生器,是一种瞬态,满量程校准法,又能直接给出两传感器随频率的延后变化量。 相似文献
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正弦压力标定方法是最理想的动态校准方法,是检验压力传感器稳定性,可靠性的最佳手段。本文介绍的是一种新型的超高压正弦压力发生器装置。该装置产生10MPa-1000MPa的正弦 ,其频率范围可覆盖目前枪,炮膛压测量的使用范围,重复性好,精度高,操作使用方便。 相似文献
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正弦压力是一种典型的周期性动态压力标准信号,而正弦压力发生器正是产生正弦压力信号的关键。以转盘式正弦压力发生器为例,采用动网格技术、Reynolds-averaged Navier-Stokes方程和Spalart Allmaras湍流模型,对不同的压力发生腔尺寸和工作频率进行三维瞬态流场的数值仿真。结果表明:工作频率不变时,正弦压力动静幅值比和谐波失真度随腔体宽度增大而减小,压力均值随腔体宽度增大而增大;腔体宽度不变时,正弦压力动静幅值比随工作频率增大而减小,压力均值随工作频率增大而增大,谐波失真度呈现先减小后增大的规律;通过动网格数值仿真技术,能有效实现正弦压力研究中各种模型结构的效果预测。 相似文献
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高压动态标定技术的进展 总被引:1,自引:0,他引:1
近10年来随着中国科学技术的发展,对高压(100MPa以上)测量系统的动态标定的需求日益迫切,相应的动态标定技术也获得了很大的发展,出现了一系列新的动标装置和技术,如高压标定激波管、高压半正弦压力发生器、高压水激波管、高压快速阀门装置等.本文对其背景、装置的原理、特点及适用范围等进行了综述和评论. 相似文献
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Robert F. Berg Stuart A. Tison 《Journal of research of the National Institute of Standards and Technology》2004,109(4):435-450
We describe two primary standards for gas flow in the range from 0.1 to 1000 μmol/s. (1 μmol/s ≅ 1.3 cm3/min at 0 °C and 1 atmosphere.) The first standard is a volumetric technique in which measurements of pressure, volume, temperature, and time are recorded while gas flows in or out of a stainless steel bellows at constant pressure. The second standard is a gravimetric technique. A small aluminum pressure cylinder supplies gas to a laminar flow meter, and the integrated throughput of the laminar flow meter is compared to the weight decrease of the cylinder. The two standards, which have standard uncertainties of 0.019 %, agree to within combined uncertainties with each other and with a third primary standard at NIST based on pressure measurements at constant volume. 相似文献
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在调研国外低温运载火箭抑制纵向耦合振动方案及结构的基础上,对各种可行性方案进行分析研究,从贮气型结构的气腔结构选型、消除温度对能量值的影响、低温绝热、低温结构密封、低温充气测压方案及注气型结构的注入气总量和单位流量的控制、充气测压方案等关键难点技术分析,对比双层整体套装波纹式蓄压器、双侧金属膜盒式蓄压器、囊式蓄压器、注气型蓄压器的先进性、继承性、复杂性、工作寿命、工艺性、经济性、使用维护性、可靠性等方面情况,分析对比结果表明,双侧金属膜盒式蓄压器是中国低温运载火箭抑制纵向耦合问题的最为合理可靠的方案. 相似文献
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We propose and consider the application of superconducting power transmission lines (SC PTs) using high temperature superconductors (HTSs) for further reduction of the electricity losses. To keep HTS cable at low temperature it is usual to use liquid nitrogen (LN2). Straight and bellows pipes used in SC PT have different hydraulic friction factors due to differences in the shape of the wall surfaces. Moreover, the decentering of the HTS cable, which is unfixed at the center of the pipeline, also influences the LN2 flow. In the case of long SC PTs, high power must be expended to overcome hydraulic friction. There are two methods to evaluate pressure losses. One is based on empirical formulae and another is based on the algorithms of computational fluid dynamics (CFD). Empirical formulae can estimate pressure losses for long pipes, but the decentering of the cable is not considered. CFD computations describe flow behavior taking into account cable position inside the pipeline, though there is a limit to computable length due to the dependence on the number of mesh points and computation capacity. In this paper, circulation losses and pump power are estimated in straight and bellows pipes forming circulation channels by both methods. For a 40 mm diameter cable in an 80 mm diameter pipe, with the bellows pipe segments covering 2% of the length, and a heat loss of 1 W/m, the required flow rate and pump power for a circulation of 10 km are approximately 19 L/min and 10 W, respectively. 相似文献
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The densities for mixtures of R 22 and R 114 have been measured with the variable-volume method using a metal bellows as a function of temperature and pressure. The results for three different compositions (75, 50, and 25 mol% R 22) cover the high-density region along seven isotherms between 310 and 370 K at 15 pressures from 1.0 to 10 MPa. Based on the present density measurements, the values of the excess molar volume, the volume expansion coefficient, and the isothermal compressibility have been calculated. The excess molar volumes for each mixture below 340 K are positive, whereas those above 350 K decrease with decreasing pressure and become negative at low pressures. The behavior of the volume expansion coefficient and the isothermal compressibility for the equimolar mixture are closer to that for R 114 than the average of those for both pure components. 相似文献
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目的 优化波纹管结构尺寸,最大程度地减小波纹管的应力集中,提高波纹管的疲劳寿命。方法 利用ANSYS Workbench对真空灭弧室用波纹管进行参数化建模,对其耦合速度压力复杂工况进行瞬态动力学分析,借助DOE(DesignofExperiment)技术对波纹管关键几何参数进行单目标优化设计,对优化结果进行强度校核和疲劳寿命计算。结果 优化结果符合设计要求,波纹管在耦合速度压力复杂工况下满足强度的同时,最大等效应力减小了28.8%,疲劳寿命由3 064次提高到32 260次。结论 优化后的结构有效减小了波纹管危险部位的应力集中,疲劳寿命得到提高。 相似文献
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针对在小腔体中阻抗分析仪发射连续波无法准确测得换能器阻抗的问题,提出一种在高静水压下使用脉冲正弦信号激励换能器测量阻抗的方法。以采样电阻法为基础,根据腔体尺寸确定发射脉冲个数以及可测频率范围来有效避免腔体边界反射对测量造成的影响。通过设置不同的发射频率,分别采集换能器两端及采样电阻两端的电压波形信号,利用已知频率的三参数正弦曲线拟合法分别得到波形信号的幅值和初始相位角,计算得到换能器的导纳值。改变静水压力,利用脉冲法测得0~10 MPa静水压下换能器导纳特性。实验结果表明,采用脉冲正弦信号激励的方法可在有限空间内准确测量换能器的阻抗特性;且随着静水压力的升高换能器的谐振频率发生偏移,导纳圆直径减小。 相似文献
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G.Q LuP Cheng 《低温学》2002,42(5):287-293
An experimental investigation has been carried out on dynamical pressures of the viscous compressible flow oscillating at different locations in a Gifford-McMahon (G-M) type pulse tube refrigerator operating at cycle-steady states. Measurements show that the oscillating amplitude of the pressure was largest at the hot end of the regenerator while the cycle-averaged pressure was the largest in the reservoir. The latter characteristics can be explained based on a cycle-averaged and cross-sectional averaged of the governing equations for a compressible viscous oscillating flow. The reason why the cycle-averaged pressure of the compressible flow oscillating at low frequencies in a tube increases from the wave generator toward the reservoir is analyzed. In addition, the effect of the cycle-averaged pressure on the refrigeration performance is discussed, which can be used to explain why the system with proper asymmetric charging and discharging periods has a better performance than a symmetric one in a G-M type pulse tube refrigerator. 相似文献
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采用双温双压法原理研制了一套宽温度范围、测试室压力可变的标准湿度发生器。它能够测量发生温度范围为-50~90 ℃、相对压力范围为-50~0 kPa、扩展不确定度为0.3%RH~0.8%RH(k=2)的5%RH~96%RH全量程相对湿度。其测试室尺寸为150 mm×400 mm,样气流量为5~30 L/Min。通过设计高精度饱和器压力和流量自动调节装置,采用工控机与PLC相结合的操作控制方式,实现了全自动运行。冷镜式精密露点仪和重量法湿度计的实际测试结果均验证了其不确定度。 相似文献