Reconstruction Of Velocity Distribution In Gas-solid Two-phase Flow Based On Two-layer Array Sensor

Gas-solid two-phase flow exists widely in multiphase flow system, for example, desert sand in nature, fuel transportation in field of chemical industry, metallurgy, energy sources and foodstuff, and so on, as well as pneumatic conveying and dust treatment of materiel in bulk. It is very difficult to measure some process parameters during two-phase flowing, such as flow status, concentration, flux, particle size, because the flowing rules of gas-solid two-phase flow is more complex than that of single-phase flow, together with inter phases effect. This paper makes use of the laser PT technique to measure parameters of the Gas-solid two-phase flow. The laser PT technique discussed here is a novel industrial process tomography based on a transilluminated mode, which adopts the principles of light absorption and scattering together with image reconstruction from projection to reconstruct the spatial distribution data of measured object via measuring light data modulated. It, as a non-invasive, non-contact and non-contaminative measurement, shows great advantages in industrial application. At present, this technique becomes one of international hot research issues, and its level still doesn't meet the requirements of industrial application. So the measure technology of gas-solid two-phase flow belongs to the research field urgently waiting for developing.Based on the research achievements obtained by our task team recently, this paper puts forward a novel method adopting full-orientated two-layer fan-beam optical sensor to measure the particle velocity. The profile optical projection data of measured flow field of the two layers can be obtained through being stimulated by array light source and detecting light signal at multiple angles in space, and the vertical velocity field can be reconstructed during the course of measurement in terms of n cross-correlation and backprojection algorithm. Next, the experiment researches are brought into execution through self-made experiment equipments, mainly include:1. The design thought of two-layer fan-beam optical sensor structure is presented, and array laser sensor of 5×5 fan beams structure is developed.2. Projection data is pretreated by way of digital filtering.3. Use the cross-correlation technology to measure the mean solids velocity along the chord, and simulate researches on LBP reconstruction algorithm and FBP reconstruction algorithm to reconstruct the vertical velocity field.4. In experiment research, control of serial drive mode of laser sensors, multiplex A/D transform in Visual C++6.0 are realized and the simulation experimental equipment of gas-particles flow in upright pipe are established, moreover, the vertical velocity of quartz grain flow were performed in the experiment;the results show the feasibility of this new optical measurement technology.