旋转式一孔测压管及其应用1）

由圆柱三孔型二元复合测压管的测速原理出发，提出用一孔测压管通过旋转实现平面气流速度大小与方向的自动测量，建立了相应的测试系统．通过大量实验，研究了该系统的性能．在多种回流和旋流流场测量中进行了应用．结果表明该系统测量原理正确，重复性好，精度高     

激光陀螺仪频率稳定度高精度测量系统的研制

以碘稳定激光器为频率标准，根据拍频检测的原理，建立了一套高精度的激光陀螺仪频率稳定度测量系统。经过实验验证，该系统实现了可用光功率仅为0．1uw量级的微弱激光陀螺仪频率稳定度的测量，测量精度达到了10^-11量级。该系统的研制成功为深入开展激光陀螺仪的稳频研究奠定了基础。     

寻北系统陀螺仪与g有关项漂移的场地标定

根据寻北系统的工作原理，提出了一种与g有关的陀螺仪漂移误差的场地快速标定方法。通过该方法可以在外场地简便、有效地对寻北陀螺的与g有关的漂移项进行准确测量。通过误差补偿可以保证寻北系统长时期的工作精度。     

利用地脉动试验识别楼房结构的模态参数

论述了在地脉动对结构物的环境激励条件下,进行结构物地脉动响应测量的试验原理及方法,提出了固有频率识别与振型识别的互补较正法．通过对实际楼房结构的地脉动响应测量识别结构的模态参数．识别结果表明该理论及试验方法行之有效．     

FRP混凝土结构力学性能的实验研究

本文首次引入基于马赫—曾德(Mech—Zehnder)原理的全光纤应变传感器系统到FRP混凝土结构的力学性能研究中，通过四点弯曲试验来测量试件内部的应力应变状态，并结合电测结果进行综合分析，为进一步的理论分析和计算奠定了实验基础．     

光声法测量材料热膨胀系数的实验研究

本文对光声技术测量材料热膨胀系数的原理和实验方法进行了研究,设计了传声腔结构和测试系统,该方法不仅能够测量材料横向、纵向的热膨胀系数,而且还能测量常规仪器所不能测量的一任一方向的热膨胀系数,并用该方法对复合材料Al2O3/Al的热膨胀系数进行了测量,通过已有的理论结果对该方法的测试结果的准确性进行了验证,证明了该检测方法的可靠性。     

非陀螺找北系统的计算机仿真研究

阐述了对设计的一种非陀螺找北系统进行计算机仿真的原理、方法。提出了降低系统噪 声影响、提高估计精度的多位置采样和多周期平均算法，并通过仿真对其算法原理进行了验 证。仿真程序采用多线程技术，实现了实时测量，缩短了系统反应时间。     

基于CPLD的导弹惯性测量单元模拟器设计

介绍了采用CPLD器件开发的导弹用惯性测量单元（IMU）模拟器的设计原理及其实现方法。该模拟器采用软硬件相结合的方式，可模拟某型真实惯性测量单元（IMU）的接口与输出信号。通过软件控制硬件输出的脉冲个数，可模拟真实惯性测量单元在静态和动态工作时的状态。该模拟器具有硬件体积小、成本低、可连续长时使用等特点和可轻松修改模拟器硬件电路的优点。该模拟器在某型号空空导弹惯导系统仿真实验中已经得到实际应用。     

大速率光纤惯性测量装置全温测试系统设计

阐述了“光纤惯性测量装置”的测试要求、测试系统的功能特点和设计方案，对该系统进行了软硬件设计，分析了测试程序的特点。通过对软硬件进行部分修改，该系统可以完成不同类型惯性测量装置的误差建模和综合测试。     

旋转流体斜压波三维温度结构实验研究

实验研究了负径向温度梯度下转坏系统中斜压流体的对流运动，获得了该系统中旋转流体斜压波的一般特征，通过对斜压波温度场多层次细网格测量，得到了斜压波三维温度结构和表面波状急流的温度分布，并就波－波转换的不稳定性问题作了初步分析．     

Electrical impedance string probes for two-phase void and velocity measurements

An instrumentation system was developed to measure two-phase flow velocity and void fraction. The principle of operation of this system was based on the measurement of the electrical impedance of two-phase mixtures. Two-phase velocity is estimated by time-of-flight analysis of signals from two spatially separated sensors. A technique involving measurement of both the capacitance and the conductance of the mixture was used to determine void fraction and correct for the effect of liquid distribution. The string probe instrumentation proved to be durable in air/water and steam/water flows and demonstrated an ability to measure a wide range of flow velocities (1–17 m/s) and void fractions (0.25?0.99+).     

A pulsed-wire technique for velocity and temperature measurements in natural convection flows

A pulsed-wire probe based on the use of one or two parallel wires, capable of measuring the velocity and the temperature in natural convection flows is described. These measurements are based on the analysis of the relaxation response of a pulsing wire, submitted to a very short electrical pulse. The analysis of the temperature variation on an optional second receiver wire, gives information about the velocity direction. The implementation simplicity of this probe, its good spatial precision, the lack of thermal contamination of the flow, as well as the possibility of obtaining simultaneous velocity and temperature measurements, allow the integration of the device in a multi-point measurement network, capable to deliver thermal and dynamic cartographies of unsteady convection flows.     

Measurement of velocity and kinetic energy of turbulence in swirling flows and their numerical prediction

Swirling flows are often employed in gas turbine combustion systems and high intensity industrial furnaces. A detailed analysis of the turbulence in the flow is necessary to achieve optimum combustion conditions. In this paper a method has been described to measure the turbulence levels in three directions using a hot wire anemometer. So far there is no established method available for measurement of turbulence in swirling and recirculating flows. The present method, it is hoped, will bridge the gap. The merit of the present method is the use of a single-wire probe rather than the X-probe. The method has been used for the measurement of turbulence levels in swirling recirculating flows generated by vane swirlers. From the measured turbulence levels, the kinetic energy of turbulence has been calculated and the results are compared with a well-established numerical prediction method. Mean velocity measurements have also been made using a 3-hole Pitot probe. The agreement between the measured and predicted values is quite satisfactory.     

Simultaneous Measurement of Velocity and Fluctuating Pressure in a Turbulent Wing-tip Vortex Using Triple Hot-film Sensor and Miniature Total Pressure Probe

We have developed a probe-system for simultaneous measurement of three velocity components and pressure in turbulent flows. A miniature total pressure probe is placed adjacent to the sensors of a triple hot-film probe in order to achieve the spatial resolution which is equivalent to that of the triple hot-film probe itself. The instantaneous static pressure is calculated from measured velocity and total pressure by means of a newly developed processing method based on the Bernoulli equation for unsteady flows. The measurements were undertaken in a turbulent wing-tip vortex flow. The look-up table method is employed for the calibration of the hot-film probe so accurate velocity data could be obtained over a wide range of the flow-attack angles. It is also demonstrated that the present probe-system is capable of measuring fluctuations in both velocity and pressure in the 20?C650 Hz frequency range. The distribution of the fluctuating pressure obtained by this indirect method is in good agreement with the results from direct measurements of static pressure, demonstrating the promising performance of the present method. Furthermore, an improvement in the ability to make measurements of the velocity?Cpressure correlation across the wing-tip vortex is achieved. This improvement is possible because the effects of lateral velocity components are properly taken into account in the present formulation. The investigation regarding the transport equation budget for turbulent kinetic energy shows an anomalous structure of turbulence in this flow, mainly due to the meandering of the vortex, and the measurement of pressure diffusion is found to play an important role in the characterization of this kind of flow.     

七孔探针可压缩流场测量研究

介绍了七孔探针用于亚音速可压缩流的标定方法。作为一种可以同时获得流动速度大小、流动偏角、总压和静压的气动测量装置,七孔探针被广泛应用于各种流动测量,包括可压缩流动。但是它的校准过程周期很长,代价昂贵,影响了探针的推广。本文以数值计算为手段,对七孔探针进行亚音速可压缩流校准与测量的研究。结果表明,其校准拟合精度流动角为2%,内外区的总静压相对标准偏差都没有超过3%,高于相同状态下的实验校准精度。在实际应用中,本方法用于指导传统实验标定方法,可以节约大量的标定时间和成本,使七孔探针在亚音速可压缩流的测量变得简单可行。     

Simultaneous measurement of velocity and temperature in high-temperature turbulent flows: a combination of LDV and a three-wire temperature probe

This paper deals with a simple and reliable technique for simultaneous measurement of velocity and temperature in high-temperature turbulent flows, including combustion. The technique is based on the combination of laser Doppler velocimetry and a digitally compensated fine-wire thermocouple. For temperature measurement, a two-thermocouple probe with a fine cold wire [Tagawa et al. (1998) Rev Sci Instrum 69: 3370–3378] is used, which enables in situ measurement of thermocouple time constants and accurate compensation of the thermocouple response. When tested in a turbulent wake behind a heated cylinder, the technique proves to be highly reliable and effective for investigating heat transport processes in various non-isothermal turbulent flows. Received: 24 June 1999/Accepted: 10 March 2000     

Performance of a combined three-hole conductivity probe for void fraction and velocity measurement in air–water flows

The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex air–water flows, is described in this paper. The air–water flows envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex air–water flows.     

Simultaneous measurement of velocity and pressure in a plane jet

A new technique was developed for the simultaneous measurement of velocity and pressure in turbulent flows. To accomplish this objective, a new probe (hereafter called the combined probe) that consists of an X-type hot-wire probe and a newly devised pressure probe was developed. The pressure probe was miniaturized by the MEMS fabrication process and by using a 0.1-in. microphone as a pressure sensor for improving the spatial resolution. This pressure probe was placed between two hot-wire sensors of which the X-type hot-wire probe was composed. The pressure probe was given a hemispherical tip, like that of a pitot tube, because an earlier pressure probe with a conical tip suffered from a reduction in spatial resolution. The spatial arrangement of the pressure probe and the hot-wire probe for the combined probe was carefully determined, because there was a risk that the measurement accuracy of one probe will be influenced by disturbances caused by the other probe when the two probes were placed very close to each other. Therefore, the combined probe was arranged to engender no noticeable interference between the velocity data and the pressure data measured by their respective probes. As one application of this combined probe, simultaneous measurements of pressure and two components of instantaneous velocity were performed in a plane jet. The turbulent energy budget and the cross-correlation coefficient of velocity and pressure in the intermittent region of the plane jet were estimated. The results show that the mean streamwise velocity, velocity fluctuation, and pressure fluctuation profiles were consistent with those measured individually using the X-type hot-wire probe or pressure probe. Moreover, it was shown that the integral value of the diffusion term (which should theoretically be equal to zero) in the turbulent energy transport equation was closer to zero than previous reports (Bradbury in J Fluid Mech 23(Part 1):31–64, 1965). In addition, the time variation of the cross-correlation coefficient in the intermittent region supports the vortex structure model predicted in previous studies (Browne et?al. in J Fluid Mech 149:355–373, 1984; Tanaka et?al. JSME Int J Ser B 49(4):899–905, 2006; Sakai et?al. J Fluid Sci Technol 2(3):611–622, 2007).     

Volumetric-correlation PIV to measure particle concentration and velocity of microflows

Volumetric-correlation particle image velocimetry (VPIV) is a new technique that provides a 3-dimensional 2-component velocity field from a single image plane. This single camera technique is simpler and cheaper to implement than multi-camera systems and has the capacity to measure time-varying flows. Additionally, this technique has significant advantages over other 3D PIV velocity measurement techniques, most notably in the capacity to measure highly seeded flows. Highly seeded flows, often unavoidable in industrial and biological flows, offer considerable advantages due to higher information density and better overall signal-to-noise ratio allowing for optimal spatial and temporal resolution. Here, we further develop VPIV adding the capability to measure concentration and increasing the robustness and accuracy of the technique. Particle concentrations are calculated using volumetric auto-correlations, and subsequently the velocities are calculated using volumetric cross-correlation corrected for variations in particle concentration. Along with the ability to calculate the particle concentration profile, our enhanced VPIV produces significant improvement in the accuracy of velocity measurements. Furthermore, this technique has been demonstrated to be insensitive to out-of-plane flows. The velocity measurement accuracy of the enhanced VPIV exceeds that of standard micro-PIV measurements, especially in near-wall regions. The 3D velocity and particle-concentration measurement capability of VPIV are demonstrated using both synthetic and experimental results.