| Many areas will have heavy snow in north of china in winter and it lasts long,especially in northeast china, lasting five or six months. Snow can decrease safety ofrunway and disturb aerodynamic of airplane, causing plane cannot fly on time. Withthe rapid development of modern society, the number of airport increases quickly.The problem of how to clean snow at airport quickly and efficiently relates to airportcould run normally. Snow removal vehicle at airport in our country are studied toolate, the performance of snow removal vehicle is single and the number cannot satisfythe need of clean snow quickly. Currently, mechanical snow removal vehicle is themain kind of one, but the efficient is very low. The snowdrift with cold-blowingwhich put the diesel engine，fan and air duct on the truck chassis is researched as anew type vehicle with high efficient and multifunctional. The gas from nozzles withhigh velocity which takes snow particles off runway causes low pressure on thesurface of snow, the snow particles move with the gas to realize the aim to cleaningsnow. Because of the technology of snowdrift with cold-blowing is not mature, thereare many problems of technology need to be solved, on this basis the paper studiedthe gas-solid two-phase flow when the snowdrift with cold-blowing was working, andthe effect of blowing snow was simulated which can provide theoretical basis for thestudy of snowdrift with cold-blowing.The paper studied the gas-solid two-phase flow when snowdrift withcold-blowing was working, and studied the factors of efficient of blowing snow, themain research work and methods are as follow:(1) The physical character of snow particle was studied, and then, the forceswhen the snow particle moved in the air were analyzed, the equation of snow particlemovement was established. The structure of snowdrift with cold-blowing and theoryof cleaning snow were introduced, and the problem about critical velocity wasdiscussed, and the change of critical velocity with the diameter of snow particle wasgotten. (2) The mathematical model of blowing snowdrift was established, and the fieldof gas flow was simulated when the cold blower was working, we can get the law ofvelocity distribution, pressure distribution and turbulent distribution from the result ofsimulation, the character of flow field was accord with jet flow theory. The change ofpressure field was violent in the region from0meter to1.5meter of y axis, but thechange was reposeful in the region from1.5meter to10meter. In the any section,velocity increased with y axis increasing, mean velocity in the x axis decreased frommaximum at the center to zero.With the increasing of x, velocity at center wasdecreasing. Velocity of y zone changes gently, and the whole velocity distribution wassimilar to jet flow theory, and the field boundary changed as line. Turbulent was smallin the near region of nozzle, but it was large in the distant region of nozzle, thenumber was maximum when y was5m.(3) The current method for study gas-solid two phase turbulent flow wasintroduced, and the Discrete Particle Model (DPM) was chosen for the paper tosimulate. Mathematical model of gas-solid two phase flow was established, anddistribution of snow particle at various times was gotten by using the method ofcomputational fluid dynamics (CFD). In order to fulfill the aim for blowing snow,three seconds optimal time was found for cleaning out airstrips by the result ofnumerical simulation. Based on jet flow theory, the velocity of cold-blowing was6km/h and efficiency was0.833m3/s when the depth of snow was5centimeter. Theeffect of turbulent distribution influenced the efficiency of cleaning snow, and thecurve of turbulent change during the development of field was acquired by thesimulation.(4) The effect that different section shapes of nozzle influenced blowing snowwas studied, and also the jet flow field of the two kinds of nozzle was simulated, bythis, attenuation of gas velocity in the field of circular nozzle and rectangular nozzlewas different，in other words, in the range from0meter to1.5meter, attenuation ofthe velocity field of circular nozzle was parabolic, but the rectangular nozzle’s keptconstant at first, then attenuated quickly. The effect of the two kind nozzles weresimulated, by comparison analyzed, obtained the conclusion that rectangular nozzleneeded shorter time to clean snow and had bigger blowing area, as also had highefficiency. In summary, the paper which was based on DPM model (Discrete Particle Model)calculated the gas-solid two phase turbulent flow when the snowdrift withcold-blowing was working, and obtained the rule of distribution of jet flow field ofthe snowdrift with cold-blowing. The optimal time of the snow compulsory cleaningout with cold-gas is found by the numerical simulation of the whole time when thecold-blowing was working, on this basis, the velocity and efficiency were calculated.The effect of blowing snowdrift of the two kinds nozzle were simulated and analyzed,it was found that rectangular nozzle was more benefit for cleaning snow. |
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