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用超声波速度方法测试硝酸溶液浓度 总被引:2,自引:0,他引:2
用超声波分析溶液浓度的方法是基于声速与溶液相份的关系,这种关系还受到温度的较大影响,本文报道了超声速度与硝酸溶液浓度、温度关系的测量工作,实验结果显示,在质量百分比浓度为50 ̄100%范围内,声速随浓度增加而降低;在温度为10 ̄55℃范围内,声速也随温度升高而降低。根据实验结果计算了纯HNO3液体的声速-浓度关系,本文还给出了声速法测硝酸浓度的智能仪器原理。 相似文献
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为使声学方法能对火焰温度进行精确测量,实验研究了火焰燃烧区域中空气声速与温度的关系。首先对非火焰气体环境中的声速与温度进行测量,然后在此基础上对不同燃料燃烧的火焰区域进行声速测量实验,并结合热电偶测得火焰温度,进而得到火焰中空气声速与温度的关系。结果表明:在固定距离下,与室温空气环境相比,高温烟气环境会使声波的传播时间减小,火焰环境会使声波的传播时间变长;在非火焰区域,空气声速与温度的关系符合理想气体中声速与温度的关系;在火焰燃烧区域,空气声速与温度关系偏离理想气体的声速与温度方程,与按照理想气体计算的声速结果相比,实际声速测量值偏小;对于同种燃料的火焰,随着火焰温度升高会出现空气中的声速减小的现象。 相似文献
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定容式气体微流量标准装置 总被引:1,自引:0,他引:1
介绍 工气体微流量标准装置及其性能,讨论了温度变化,气体吸附和系统汛放等干扰效应,分析了标准装置的不确定度。该标准的校准范围为1*10^-310P.m^3/s,不确定度小于1.2%,用于校准热容式质量流量计。 相似文献
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本文推导了定常粘滞流气体反扩散方程一维形式的二种解。1.根据盖德-雅开尔扩散泵理论导出园管任意截面X反扩散量F(X)=n·e(q/D0)x·u(n1;表示x= 0处反扩散气体浓度, q是单位面积正向气体流流量,u是正向气体体积流量,D0是扩散系数)。结果与实验有较大分岐。 2.考虑正向气体流速V径向抛物律分布,分层独立反扩散获得:F(x)=8/9n1v (D0/qx)2。式中F(x)~1/q2以及F(x)~D02关系符合L.Holland依靠粘滞流阻挡机械泵油的实验结果以及Wertenstein的早期实验结果。但是理论予示F(X)~1x2,而实验结果F(x)~1/x。 本文还推导了三维空间(柱座标)定常气体粘滞流反扩散方程的一般形式。对于特定情形(平行板)二维空间的二种情况尝试,应用广义付上叶级数求出反扩散流的浓度分布,显然这项工作还要作下去。 最后介绍了反扩散方程及其解在真空技术-尤其在应用扩散泵系统获取清洁真空方面的种种应用。 相似文献
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甲醛分析仪现场检测技术 总被引:1,自引:2,他引:1
采用扩散管动态配气装置发生甲醛标准气体,对BH-1型甲醛快速分析仪的各项性能指标(响应时间,稳定性)进行了测试,确定了分析条件(温度,相对湿度,风速)对仪器的影响,结果显示快速分析仪测定甲醛气体浓度的相对误差小于10%。研究表明经定期校准的甲醛快速分析仪用于室内甲醛气体污染的检测可获得可靠的结果。 相似文献
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粘滞气体不可压缩性的适用条件探讨 总被引:1,自引:0,他引:1
从粘滞流体的动力学方程出发,导出了粘滞气体不可压缩性的适用判据,结果表明:粘滞气体许可的最大流速比传统的判据低1/3,并且还要求流速在流动方向上的二阶微商远小于垂直方向的二阶微商,最后讨论了气体不可压缩性适用的空间尺度。 相似文献
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用于瞬态高温测试超声波传感器 总被引:1,自引:0,他引:1
目的 研究一种用于测试瞬态高温的传感器。方法 设计超声波发射和接收装置用来测量超声波声速,根据超声波的相关原理,声速的大小可以反映被测气体的温度值。结果与结论 超声波瞬态高温传感器是一种非接触式测量传感器,动态响应好,可用于气轮机进气、火箭排气、汽缸燃烧气体,火炸药虹破燃烧等场合的温度测试。 相似文献
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P. J. Kortbeek N. J. Trappeniers S. N. Biswas 《International Journal of Thermophysics》1988,9(1):103-116
A gas expansion technique has been used to determine the pVT properties of N2 up to 1 GPa at 298.15 K, with an accuracy of 0.08% in density, 1 mK in temperature, and 0.05%+0.2 MPa in pressure. The sound velocity has been measured by a phase-comparison pulse-echo technique between 123 and 298 K at intervals of 25 K and at pressures up to 1 GPa, with an accuracy of better than 0.02% in sound velocity, 10 mK in temperature, and 0.05%+0.2 MPa in pressure. An equation of state is presented that correlates the density data over the wide pressure range of 36–1000 MPa with maximum deviations between the calculated and the experimental densities of less than 0.05%. 相似文献
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The transient process of rock, normally impacted by a gas gun, was monitored with a thermal infrared (TIR) imager. The geometric features and the radiant characteristics of the infrared thermography in target region were extracted and regressively analyzed. Both the projectile's impacting velocity and kinetic energy were back analyzed based on the extracted geometric features and the radiant characteristic parameters of target thermography. It was revealed that: (1) there is a critical velocity at which target thermography is regular and centrally symmetrical; (2) within the critical velocity, the impacting velocity is linearly correlated to the perimeter of target thermography and is quadratically correlated to the TIR temperature increment, while the projectile kinetic energy is linearly correlated to both the area and the increment of the TIR radiant flux of the target thermography; (3) for a quantitative back analysis of the impact-related parameters, both geometric features and radiant characteristics can be applied. It was suggested that the perimeter and the TIR radiant flux increment of the target thermography can applied as the principal indices (with an error of less than 5%), while the area and the TIR temperature increment of target thermography can act as other auxiliary indices (with an error of less than 15%). The possible mechanisms of variations in IR radiation for impact on rock are discussed. The results are of general significance for the impact on other types of rocks or solid materials, and might extend the application of infrared remote sensing from a static geosciences domain to a dynamic mechanical domain. 相似文献
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To analyze the effects of higher wall roughness on dense particle–laden dispersion behaviors under reduced gravity environments, a dense gas–particle two-phase second-order-moment turbulent model are developed. In this model, the wall roughness function and the kinetic theory of granular flows are coupled and closed. Anisotropy of gas–solid two-phase stresses and the interaction between gas–particle are fully considered using two-phase Reynolds stress model and the two-phase correlation transport equation. Numerical simulation test is validated by Sommerfeld and Kussin (2003) experiments data with higher wall roughness 8.32 μm. Predicted results showed that the particle concentration distribution, particle fluctuation velocity, particle temperature and particle collision frequency are greatly affected by higher wall roughness, as well as particle Reynolds stress and interactions between gas and particle turbulent flows are redistributed. Under microgravity conditions, particle temperature and collision frequency are greatly less than those of earth and lunar gravity. 相似文献
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V. G. Beketov 《High Temperature》2000,38(1):131-140
Analysis is made of the experimental data available from the literature on the solubility of ice and water in various compressed
gases in a wide range of temperature and pressure. A new formula is derived that relates the equilibrium concentration xeq of steam in moist gas at preassigned temperature and pressure to the constants of the equations of state for condensed water
and to the virial coefficients. This formula enables one to directly calculate the solubility of steam in compressed gas without
using the previously suggested solution of the set of equations. The derived formula makes it possible to describe the entire
array of experimental data in the range of parameters from 200 to 400 K and from 0.1 to 10 MPa with an error equal to or less
than the experimental error 相似文献
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采用热蒸发法成功制备氧化锡纳米线。用X射线衍射、扫描电子显微镜和透射电子显微镜对所制备纳米线的晶格结构和表面形貌进行表征。所制材料为金红石氧化锡单晶结构,纳米线直径为50~200nm,长度为5~15μm,符合气-液-固生长机制。以氧化锡为气敏材料,制备了旁热式结构气敏元件,测试该元件对浓度范围为25×10^-6 ~500×10^-6 的乙醇气体环境的敏感性能。结果表明,该元件的最佳工作温度约为260℃;在25×10^-6 和500×10^-6 的乙醇气体中,灵敏度分别为7.54和111.01,响应时间为2~20s,恢复时间为5~33s;在测试范围内灵敏度与气体浓度具有良好的线性关系;7天内重复测量误差在5%以内,稳定性较好。 相似文献
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为研究声速法接收信号幅值的变化对温度场重建的影响,基于声学测温法开展了热校准风洞模拟试验,成功模拟了航空发动机燃烧室出口的温度场重建。首先从接收到的信号数据中提取特征,建立特征矩阵,用以反馈信号幅值的变化;然后,基于采集到的信号数据,通过最小二乘法进行温度场重建;最后,通过比对不同特征矩阵下温度场重建的实际效果,分析声速法采集的信号幅值的变化对温度场重建的影响。通过试验验证可知:接收信号幅值越大,重建温度场的均方根误差越大,当幅值大于理论值40%时,均方根误差大于理论值14.38%;接收信号幅值越小,重建温度场的最大相对误差越大,当幅值小于理论值40%时,最大相对误差大于理论值44.3762 K。本文的研究对推动声学测温技术在航空发动机燃烧室出口温度场测试领域的发展起到促进作用,具有重要技术借鉴价值。 相似文献
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本文采用标准的k-ε三维紊流模型,利用FLUENT软件对喷嘴型真空高压气淬炉中空炉冷态流场和工件满装炉量下气固耦合流动传热过程进行了数值模拟计算.建立了符合实际的控制方程和简化物理模型,对空炉冷态下炉内的气体流动特征点进行流速测量,通过实测值与计算机模拟结果进行对比,验证了流场模拟计算的准确性和适用性;预测了满炉状态下炉区内的气体流动和工件温度分布,实测了指定工件的冷却曲线,比模拟冷却时间慢,误差在10%以内. 相似文献
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为准确测量、计算得到烟气再循环率,在燃气组分及浓度不变的情况下,基于化学反应平衡方程式推导得到烟气再循环率的计算公式,进而提出测量燃气锅炉烟气氧浓度和烟气-空气混合气氧浓度的双氧法。为定量分析测量结果的质量,基于国标中的GUM法对双氧法进行不确定度评定,并根据不确定度要求为仪器选择提出指导意见。研究发现,当烟气氧浓度测量结果为1.91%、混合气氧浓度测量结果为18.64%时,通过双氧法计算烟气再循环率R为13.45%,扩展不确定度为1.56%。混合气氧浓度测量不确定度对双氧法扩展不确定度影响很大,在选择测量仪器时,混合气氧浓度测量仪器的扩展不确定度可小于烟气氧浓度测量仪器。 相似文献