Advanced Materials Research Vol. 508

Abstract: In comparison with cross correlative method based particle velocity measurement, the spatial filtering method for particle velocity measurement has the advantages of simplicity of the measurement system and convenience of data processing. In the paper a capacitive velocimeter, based on the spatial filtering method, is described. In this approach a capacitance sensor array has been used as a spatial filter for particle velocity measurements. Experiments were performed on a test rig and the experimental results show that the system relative error is within ±4% over a velocity range of 2-5m/s for a moving particle.

Abstract: Air drilling technology has been widely used in the oil and gas exploration, coal, geothermal, geological exploration, nuclear industry and other fields due to its high drilling rate and low cost. However, the design of the pneumatic conveying system for the mineral detritus is still largely based on empiricism. The paper was set in the background of gas drilling, mainly studied the gas-solids two-phase flow characteristics in 90 degree bent annular pipe and backward-facing step of an annular pipe, which are very important parts of air drilling. They refer to the bent part and backward-facing step of an annular channel formed by the drill pipe and the borehole wall. A detailed numerical simulation and experimental studies were carried out for the flow structure and pressure losses of gas-solid two-phase in the annular pipe of gas drilling. Since a unified theory has not been developed for the two-phase flow in annular pipe, a lot of experimental work should be conducted. In the experimental research, the paper independently designed and built an annular pipe pneumatic conveying system with 90 degree bend and backward-facing step, including designing material screw feeder, material receiving hopper, pipeline, control system, data acquisition system, and etc. As known, many parameters, such as gas velocity, diameter and density of the particle, and solids loading ratio, can influence the conveying process. How these primordial influence factors act on the pressure losses of two-phase flow in annular pipe was analyzed in this paper. In the numerical simulation research, turbulent two-phase flow calculations were performed with a commercial CFD computer code referred to as FLUENT to study the gas-solid two phase flow in the sections of backward-facing step and 90 degree bent pipe respectively by using Euler-Lagrange method. The RNG κ-ε model and stochastic tracking were involved in the calculation of turbulence dispersion of two phases. The discrete phase model was performed for the solid phase. In the end, the numerical study 3-D results were translated to 1-D results using the standard averaging transformation to compare with experimental results. Predicted results obtained for pressure drop and velocity variations in full developed flows in the cases examined are in good qualitative agreement and are not in quantitative agreement with experimental data. The deviations between the simulations and experimental data lie in the range of 20%-30%. These results suggest commercial CFD codes such as FLUENT can be used productively for investigations into gas-solid two-phase flow phenomena and as an aid in pneumatic conveying design. The studies of the two-phase flow characteristics in the paper will contribute to reliable determination of the optimal condition of pneumatic conveying in gas drilling.

Abstract: In this paper, the comparation and analysis of the conner detection algorithm used in the three-dimensional reconstruction were made .Also the improvement and optimization to the parameters of harris algorithm were done. It is concluded that the hariis algorithm improved had a better effect ,simpler operation and better stability in the measurement of material stack volume measurement through the experimental results.

Abstract: In order to improve characteristics and to increase reliability of board systems used at researches of the ground objects, estimation of natural resources and control of ecological state of environment, determination and estimation of accidents and explosions of industrial fields, etc. the structural and methodological solutions are offered. At that increase of system response speed and reliability of received results are provided.