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Wei Wang, Yuming Shen
Implementation and Application of SOPC-Based Pulse Interpolation Technology

When Pulse interpolation technology emerged and was introduced into flow calibration device, the volume is reduced , furthermore, the calibration time is shorten, so calibration efficiency is improved greatly.However, pluse interpolation technologies is difficult and complex to implement, and in this paper a simple, stable and multi- function method is presented.

Mou Changhua , Wang Maolin, Peng Lihui
A Novel Thermal Senor for Gas Flowmeter Measuring

Thus far, the thermal gas flow sensor is commonly based on the constant current principle. However, the constant current thermal sensor suffers the zero drift because of the tolerance of manufacture. And the accuracy and the response time of constant current thermal sensor cannot fulfill the application with high accuracy requirement. The paper presents a novel thermal sensor for gas flow measuring, which is based on the constant power techniques. Experiment results demonstrate that the novel constant power thermal sensor is of high accuracy, short response time and small zero drift.

Zhen-ya Wang, Ning-de Jin, Zhong-ke Gao, Rong-hua Xie, Xing-bin Liu
Identification of Vertical Upward Oil-Gas-Water Three-Phase Flow Pattern Based on Nonlinear Analysis Method

In order to study oil-gas-water three-phase flow characteristics in oil well, the vertical upward three-phase flow experiment at low velocity was carried out in a large diameter (125 mm ID) flow loop using the combination instrument of vertical multi-electrode array (VMEA) conducatance sensor and mini-conductance probe array, and the conductance fluctuating signals of five three-phase flow patterns with water as the continuous liquid were acquired. The nonlinear dynamical characteristics of the five flow patterns were represented by nonlinear analysis method, which are chaotic attractor morphological description and complexity measures including Lempel-Ziv complexity and approximate entropy. The study results indicate that chaotic attractor morphological characteristics could identify three-phase flow pattern; the combination of Lempel-Ziv complexity and approximate entropy could serve as the classification criterion of the flow patterns mentioned above. The nonlinear information processing and analysis of time series provides a new approach to studying the dynamical evolution mechanism of the complex multiphase flow.

Jin-Ming Zhang, Yi-Ping Liu
A Design of Capacitance Sensor System for Void Fraction Measurement in Liquid-Gas Flow

The sensors, consisting of METC axial synchro driving guard electrodes and two sets of detecting electrodes, make it possible to obtain simultaneously two groups of signals of the void fraction in liquid-gas two-phase flow. The quality of the reconstructed image and the performance of multielectrode capacitive system depend on the uniformity of sensibility distribution between electrode pairs. To determine the spatial sensitivity distribution over the pipe cross section and to study the static responses of the system, a numerical simulation has been employed to analyze the design parameters and the system performance of the capacitive systems. As a consequence, a prototype of 12-electrode internal sensors with METC configuration is presented as first part of ECT system used in liquid-gas flow void fraction measurement.

Xu Ying, Zhang Qiang, Zhang Tao, Li Tao, Duan Yu-han, Li Zhen-lin
Research on the Two-Phase Flow Measurement of Condensate Natural Gas

This research is on the implementation of online non-separation flow measurement of gas-liquid two-phase condensate natural gas. The V-cone throttle device, which has the shrinkage characteristics of fluid-flux sectional area along the outside surface of its core and the inside surface of its pipe wall, and the venturi throttle device, which has the shrinkage characteristics of fluid-flux sectional area along the center of its tube, are assembled. Then the two overreading measurement models are built up according to the different characteristics of the two overreading measurement values and their inherent law respectively. Using the iterative correction method repeatedly, the flowrates of the gas-liquid two-phase can be implemented respectively. Taking a prototype with DN80 diameter designed and made for example, with the experimental devices of the wet gas flow measurement, the experimental research and the performance verification of the prototype is carried out in the flow laboratory of TianJin University. The results indicate that the error limits of gas flowrate and liquid flowrate are less than ± 2 % and less than ± 10 % respectively. Meantime, a series of experimental research and performance verification are carried out in industrial fields of Southwest oil and gas fields of Petro-China. The results showed that the accumulated flow error of both the gas and the liquid is less than 1% respectively.

Andreas Brümmer, Roland Edlerherr, Johann Lenz
Experimental and Theoretical Investigation of Thermoacoustic Oscillations in Natural Gas Metering Stations

In natural gas flow metering and pressure regulation stations flowmeters, heat exchangers and control valves are usually connected in series. Especially in case of two and more measuring bars sometimes at minor flow rates untypical pipe vibration together with flow metering faults are observed. Based on field investigations the dependencies between the pipe vibration level, the gas pulsation inside the pipe and the operating conditions of the heat exchanger are analysed. It turns out that with increasing heat flow rates into the natural gas the pulsation and hence the metering faults as well as the pipe vibrations are amplified.
In order to understand the physical dependencies of this phenomenon besides experiment a theoretical study is performed. The root cause of the vibration turns out to be thermoacoustic instability. According to the Rayleigh-Criterion gas pulsations are amplified, if heat will be given to the gas in the moment of greatest condensation. Based on detailed theoretical investigations by means of a method of characteristics the physical dependencies are analysed. Finally potential solutions to avoid this vibration problem at natural gas metering stations are introduced.

Alexandre T. P. Alho, Maria H. Farias, José L. S. Neto
On the Design of a Circulating Water Channel for the Brazilian National Institute of Metrology – INMETRO

Circulating water channels provide a controlled flow environment in which a wide variety of experiments may be conducted. The Fluid Dynamics Metrology Division of INMETRO - Brazil, has designed a circulating water channel that is particularly suited to the characterization of flow phenomena. The facility was designed to conduct research on general flow phenomena with liquids as those related to environmental management and pollution control, turbulence and velocity measurements, flow meters calibrations, among others. In this paper, major issues related to the design of the water channel for INMETRO are discussed. In particular, CFD analysis of the performance of the flow conditioning devices installed and its relation to the velocity distribution along the working length are presented. Also, the feasibility of using the superconducting magnetic levitation technology to drive the movable bridge is discussed.

Zhou Guo-xiang, Wang Jing-an, Li Chunhui
Study on the Tests of Large-Bore Flow Measurement Using FJPE-Type Gauging Pipes

Several tests using FJPE-type gauging pipes for improving the accuracy of large-bore flow measurement have been described herein. The measuring test of non-fully developed pipe flow, which is formed in the elbow, is discussed especially, including research processes, part of data-processing result, and flow velocity profiles at the cross-section of pipes. The initial results indicate that, measurement of large-bore flow by varied-bore pipe is of significant flow-rectifying effects, which reduces the length-requirements of straight tubes as well. The gauge constant fluctuated little within the larger Reynolds number range. This kind of research provides a new method for large-bore flow measurement.

Wu Jian, Chua Hock Ann
Blockage Effects in the Calibration of Anemometer in a Wind Tunnel

Anemometers are commonly calibrated using wind tunnel systems. Due to the finite volume of the test section of wind tunnels, measurement results obtained in the wind tunnels often do not resemble those obtained under the condition of infinitely spaced boundaries as the blockage effects of anemometers cannot be neglected. This paper describes an experiment carried out to analyse the blockage effects of anemometers in a wind tunnel having effective test size of ∅ 180 mm x 300 mm which covers the velocity range of 0.1 to 60 m/s.

Pier Giorgio Spazzini, Riccardo Malvano, Aline Piccato
Re-Design of a Wind Tunnel Outflow Section

This paper deals with some of the problems connected with the design of a wind tunnel. In particular, the flow in the diffuser is analyzed in detail. The tool for this analysis was the numerical simulation, which allowed to forecast possible problems and to set up strategies to overcome them before the device was built. The simulations required to reach this aim will be presented, alongside with the results obtained. The results will be discussed in the light of the objectives of the device, which is designed to improve the performance of a reference test rig for airspeed measurement.

Page 234 of 977 Results 2331 - 2340 of 9762