Dailiang Xie

A New Method for the Flowrate Measurement of Gas-Liquid Two-Phase Flow

A new method for the flowrate measurement of the gas-liquid two-phase flow is proposed. A multi-circle flowmeter is designed based on the measurement principle of the conventional loop flowmeter. Four differential pressure signals are obtained from the multi-circle sensor at different positions. Multi-parameters of the two-phase flow are obtained. The total flowrate measurement models of the two-phase flow are established using the average values of the differential pressure signals. Four measurement models are compared and the optimal ones are selected to calculate the density and the volume fraction of the mixture. The measurement of the liquid flowrate and the gas flowrate is realized associated with the volume fraction. Experimental results show that the measurement accuracy is satisfactory.

Uncertainty model and estimation for emissivity of a steel plate with a multi-wavelength pyrometer

A technique was described in which a multi-wavelength pyrometer was used to measure a sample temperature with its short wavelength based on the reflectivity measurement and then to obtain the normal spectral emissivities at longer wavelengths. The normal spectral emisivities of a roughened and slightly oxidized steel plate were measured with this technique at four wavelengths. The standard relative uncertainty of normal spectral emisivities for the sample at 1000°C was less than 2%.

Research on the algorithm of visual particles inspection based on machine vision

To detect visual particles in pharmaceutical ampoule on line, a detection algorithm base on machine vision was designed. Firstly, to capture the original image through the camera, and then image technique difference and energy accumulation was used to remove the background noise,therefore the target image only with visual particles and air bubble noise was acquired. Secondly, the edge of the targets in the image were extracted through the edge detector. Finally, to distinguish the visual particles from the noise in the image base on the difference of diaphaneity in their edge region. A large number of experimental results show that the method is effective.

Flowrate measurement of gas/liquid two-phase flow base on the double-cone flowmeter

In this paper, the experimental studies were conducted on the gas/liquid two-phase flow by using a new double-cone flowmeter with diameter ratio of 0.8 in the 50mm-diameter horizontal pipe. The discharge coefficient of the double-cone flowmeter was calibrated by experimental methods in the water standard facility. The homogeneous model and the James model were applied to measure total flowrate of the gas/liquid two-phase flow, and the measurement errors were analyzed. A modified homogeneous model was proposed. The experimental results show that relative error of the modified model is within 6%, which indicates that the new model is effective to the total flowrate measurement. At the same time, it may prove that the double-cone flowmeter can be used in gas/liquid two-phase flow measurement.

Numerical Simulations of Fluidic Flowmeter with Large Measurement Range

A fluidic flowmeter with new structure is designed in this work on the basis of the traditional ones in order to obtain wide measurement range. This fluidic flowmeter has the diffuser wall with polygonal line and it has the performance of adaptability and stability. The CFD software FLUENT is employed to the numerical simulations of the fluidic flowmeter. The linear-relationship of oscillation frequency flowrate is obtained in the wide measurement range through the analysis of the data. The simulation results show that the oscillation of this fluidic flowmeter is stable and reliable. The formula of the flowrate and the oscillation frequency is obtained. The lower limit of the measurement and the pressure loss of the oscillator are also analyzed. Some useful theoretical information can be provided for the design of fluidic flowmeter in this work.

Development of the Multi-point Thermal Gas-mass Flowmeter

A multi-point thermal gas-mass flowrate measurement method is designed. The meter has four hot-film sensoring elements. Four often-used arrangements of the sensing elements are studied and the optimal disposition is selected. The temperature characteristics of the hot-film probe are analyzed under different surrounding temperature conditions and different currents passing through the hot-film probe. The relationship between the resistance of the probe and the ambient temperature is obtained. The automatic compensation method is applied to the temperature compensation. The curve fitting method is employed to calibrate the multi-point thermal gas-mass flowmeter. The gas flowrate is measured according to the output of the sensing elements array through curve fitting. The test results show that the multi-point method is satisfactory

Analysis of upstream installation effects on the discharge coefficients of averaging Pitot tubes using CFD

It is difficult to acquire or calibrate the discharge coefficient of averaging Pitot tubes, especially for large diameter pipes. Simulations and experiments were carried out to obtain the measurement characteristics at the situation where there are not enough long straight pipe to ensure the fully developed fluid. The goal of this paper is to do some preliminary numerical tests on acquiring or calibrating the discharge coefficient of averaging Pitot tubes applied at the large diameter pipes with upstream single elbow, double elbows in-plane or double elbows out-of-plane. Standard k-ε turbulence model was used in simulations. The velocity profile of downstream elbows was illustrated and investigated. The discharge coefficients of averaging Pitot tubes are obtained from both simulation and experiments. The results show that the disturbed flow results in positive or negative shifts for the discharge coefficients. In terms of deviations of the coefficient downstream elbows and that at fully developed flows, and with prediction models, some attempt can be made to correct the coefficient with elbows upstream in large-diameter conduits.

Flowrate measurement of air-water two-phase flow with double-cone flowmeter

A differential pressure flowmeter with double-cone structure was designed and employed to measure air-water two-phase flow. Five double-cone flowmeters with different equivalent diameter ratios of 0.840, 0.780, 0.697, 0.586 and 0.424 were manufactured and their measurement characteristics were analyzed. Experiments were carried out for the flowrate measurement of the air-water two-phase flow on a horizontal multiphase flow facility by using this flowmeter. A good linear relationship between the prospective gas flow ratio and the Lockhart-Martinelli number was investigated through analysis of the experimental data. Total mass flowrate model of double-cone flowmeter for air-water two-phase flow was established based on the Bizon model. The James model, separated flow model, Murdock model and Lin model were also applied to measure total mass flowrate of the air-water two-phase flow, and the measurement errors were analyzed and compared. The experimental results show that the total mass flowrate measurement error of the proposed model can be within 6% by using the new double-cone flowmeters. Compared with other models, the proposed model is more suitable for the double-cone flowmeter.

Numerical simulation studies on a microfluidic oscillating flowmeter

A feedback-driven microfluidic oscillating flowmeter for the need of the miniaturization of flow sensors in the MEMS flow control system is presented. Numerical simulation method is employed to study the measurement characteristics of the microscale fluidic flowmeter, the simulation results show that this microfluidic oscillating flowmeter has the feature of oscillation stable, sensitive switch, the Strouhal number being a const in a wide range of the inlet velocity and the small initial oscillation velocity down to 0.075m/s. The attempt in this work may provide some useful information for design and optimization of the microscale fluidic flowmeter.

Study on method of improvement about Annubar Flowmeter base on numerical simulation

For the difficulties of obtaining the discharge coefficient of the Annubar Flowmeters at large diameters, some attempt were made to improve this meter based on the numerical simulation. Some researches were done on two flowmeters with different blockage ratio under the condition of fully developed fluid by using standard k-ε turbulence model. The measurement characteristics of both flowmeters, such as pressure loss, linearity of discharge coefficient were calculated and compared. The results show that the impact of surface roughness is small. Linearity of discharge coefficient of both flowmeter is agreed with experimental results. The pressure loss of improved flowmeter is smaller than before. The experimental measurement characteristics of improved one are agreed with the simulation. Larger output differential pressure could be obtained.