【作者】 刘同帮；

【导师】 白彦华； 曲迎东；

【作者基本信息】 沈阳工业大学 ， 材料加工工程， 2011， 硕士

【摘要】 喷射成形工艺中,雾化熔滴尺寸的大小是衡量沉积坯料质量好坏的一个重要标准,细化熔滴尺寸是气雾化技术领域研究的热点。根据气雾化液流的波动破碎理论,本研究提出以振荡气体雾化金属液,从而细化熔滴这一新思路,利用数值模拟、实验测量、机理分析等手段,展开了对气源振荡雾化技术的研究。完成了气源振荡装置实体的设计。此装置可以制备出频率为100Hz的振荡气体,振荡幅度的大小可以通过更换不同尺寸的转子叶片来调节。通过对纯Al的雾化实验,验证了此装置的适用性。利用CFD软件,对振荡气体流场结构进行分析。结果表明：振荡气体与无振荡气体的流场结构有相似性,但振荡气体流场中的在一个周期内的速度最大值,要小于无振荡气体流场中的最大速度值；气体振荡对回流区温度的影响不大；振幅对气场结构的影响最为明显,振幅越大,在一个周期内流场的变化越明显；频率越高则气场中实际各参数比理论参数滞后性越明显。通过雾化试验观察,发现主压力对雾化质量影响最大,随主压力升高雾化提前终止或失败。对课题所使用的喷射成形设备,在主压力为0.5MPa时,金属液可以得到充分的雾化,在主压力为0.3MPa,振幅为0.1MPa时,频率为100Hz的振荡气体雾化效果要比气源无振荡,压力为0.3MPa时的雾化效果好。利用DPM模型,对液滴的尺寸进行了预测,结果表明：在某些压力参数下气源振荡比气源无振荡可以雾化出更细液滴。针对液滴尺寸的数值计算结果,对气源振荡雾化机制进行了分析：冲击波作用在液流扰动波的位置和时间上的差异是液滴尺寸不规律变化的主要原因。更多还原

【Abstract】 In spray forming process, the size of the melt drops aerosol is one of most important standards of measuring deposition blank quality. Fining melt drops of aerosol size is one of hotspots in researching technical field. According to the smog of fluid flow theory, this paper proposes the fluctuation broken with oscillation gas atomization liquid metal, thus refining melt drops Using numerical simulation, experimental measurement, mechanism analysis and other ways, launched in researching air oscillation atomization technology.Finished the design of air oscillation device. This device can produce the frequency of l00Hz oscillations gas, which can change oscillation range by the size of the rotor blades. Through the experiments of pure Al atomization verified device applicability.Using CFD software, analyzed the oscillation gas flow structure. The results show that the flow field structure of oscillations gas had is similar with ordinary atomization gas, but the maximum speed in one cycle of oscillations gas flow field is less than that of the ordinary atomization flow field. The temperature of backflow zone is not obviously affected by gas oscillation. The most obvious influence in structure is the amplitude of gas, more higher amplitude, much more obvious changes of flow field in a cycle; and more higher frequency, much more obvious hysteresis in actual parameters than theory parameters.By atomizing the experimental observation, discovered that the most biggest influence of atomization quality is main pressure. The atomization will be ended or failed with increasing main pressure. For this paper, using injection forming machines, liquid metal can get sufficient atomization when the main pressure is 0.5MPa, The atomization is much better when the main pressure is 0.3MPa, amplitude is O.1MPa, frequency is 100Hz other than non oscillation of source gas, 0.3MPa of main pressure.Predicted the size of drop using DPM model, The results show that more finer drop can be got under oscillation source gas other than non oscillation source gas in certain parameters.Aiming at droplet size of numerical calculation results, the air source oscillation atomization mechanism is speculated that the position and time diversity which shockwave effect in fluid flow disturbances wave is the main reason of irregular changes of droplet size.更多还原