Hongjun Sun

A Novel Digital Lock-in Amplifier with Dual Channels

In order to sample two channels mixing frequency signals in high speed and process them synchronously in the system, a dual-channel, high-speed digital lock-in amplifier (LIA) that uses orthogonal digital demodulation is proposed. The instrument, based on a digital signal processor (DSP) and its associated hardware, is implemented. The system adopts a method of high speed bi-directional parallel communication between DSP and parallel interface of PC by EPP (Enhanced Parallel Port) protocol. The EPP achieves an easy installation for industrial applications. The experimental tests showed that the system is feasible.

The experimental research of vortex flowmeter in vertical upward gas-liquid two-phase flow

It is researched about the measurement characteristics of vortex flowmeter in air-water vertical upward two phase flow in this paper. The diameter of the pipeline is 50 mm, the flow velocities of the water vary from 0.849 m/s to 1.415 m/s and the void fraction of the gas is 1% to 20%. According to the experimental results, the repeatability of the vortex flowmeter can be used as a criterion for the stability of the flow. Meanwhile, the fitting formula is also given for the instrumental coefficient of vortex flowmeter through the analysis of the measurement error.

Crane tracking and monitoring system based on TLD algorithm

Aiming at tracking performance of real-time and robustness of crane monitoring system, current target tracking methods are contrasted in this paper, such as Tracking-Learning-Detection (TLD) algorithm, MeanShift and particle filter. Experimental results show that MeanShift and particle filter algorithm have the advantage over TLD in real-time performance. However, TLD can adapt to the crane transformation with preferable self-learning capability. And TLD enables to re-track the object even if the object is sheltered or missed momently. Therefore, the crane monitoring system based on TLD algorithm can not only detect and track the target accurately but also be superior to another two algorithms in performance of robustness.

The experimental research of vortex flowmeter in vertical upward oil-gas-water three-phase flow

An experiment of vortex flowmeter in oil-gas-water vertical upward three phase flow has been reported in this paper. In this research, the diameter of the pipeline is 50mm. The flow of the water varies from 5m3 /h to 8 m3 /h. For the total mixed flow, oil is occupying from 5% to 30%, and the gas proportion of the void fraction is from 1% to 5%. The results show that the measurement error of oil-gas-water three-phase is relatively small and has direct reference value for measuring the oil-gas-water three phase flow. The experiment showed that the volume measured by the vortex flow-meter was less influenced by media with low gas content.

Mass flowrate measurement of wet steam using combined V-cone and vortex flowmeters

The accurate measurement of wet steam has great significance for energy conservation and sufficient utilization. However, subject to the complex flow characteristics of vapor steam and discrete droplets, there are many problems in wet steam metrology. A dual-parameter model combining V-cone and vortex flowmeters was proposed to calculate mass flowrate of wet steam. The vapor mass flowrate is obtained by vortex meter coefficient and vapor density; its over-reading is obtained by the measured V-cone two-phase differential pressure and vapor density. The ratio of these two results was defined as over-reading factor. The correlation between over-reading factor and Lockhart Martinelli parameter is established by calibration experiments to get the dryness and the mass flowrate of wet steam. The proposed wet steam meter predicts the wet steam mass flowrate within the accuracy of ±6% from 95% tested samples, which indicates the efficiency of the proposed approach was validated.

Probe design based on three-axis acceleration measurement

To improve the anti-vibration performance of vortex flow meter, we propose a new design of vortex probe based on acceleration measurement. Mode and harmonic response analyses of probe structure are carried out by using finite element analysis software. Selections of material and optimized mechanical structure of probe are given by simulation results. Both simulation and experiment results indicate that the new design can apply to measure the vortex shedding and also expand the frequency band within a certain range.

Numerical simulation and experimental study of the vortex flow around a bluff body in horizontal gas-liquid two-phase flow

Numerical simulation and experimental tests were undertaken to study the vortex stability of gas-liquid two-phase flow around a bluff body in a horizontal pipe. A 3-D Computational Fluid Dynamics (CFD) modeling is carried out in order to model the gas-liquid two-phase flow around a bluff body using a volume of fluid (VOF) model. The captured photographs of typical flow patterns are used to compare the CFD predictions and a good qualitative agreement is observed between them. The relationship between the Strouhal number and cross-sectional void fraction is derived from the experimental data. The vortex stability is analyzed in terms of frequency, Strouhal number and the requirement of vortex stability.