冷喷涂加热器数值模拟

Simulation for gas heater of cold spray system

摘要:

为了缩短冷喷涂设备的研发周期和降低设计的复杂性,采用数值模拟技术分析冷喷涂加热过程中空气的换热特性．通过计算流体力学(CFD)软件Star-CCM+,分析了输入功率、加热器电阻元件结构和气体流量等因素对气体出口温度的影响．结果表明:管内气体的速度不会发生较大的变化,整个加热器可以达到一个稳定的温度场分布,加热管的温度和气体最高温度间存在较大的温度差．合适的结构设计可提升换热效率、降低气体和螺旋管间的温度差、提高加热器的工作温度．将螺旋管的中心距增大,可以提升气体的湍流度,提升换热效率;螺旋管间距缩小才能增加出口的温度．螺旋管的直径为8～12 mm时为宜,过大过小都会导致换热效率降低．

Abstract:

To shorten the research and development period and to lower the complex of design of cold spray system, a commercial software Star-CCM+(Version 6.04) is used to calculate the state of gas flow, the relationship between exit temperature and the structure of gas heater, flow rate and heat input. The results indicate that a steady temperature can be reached for the whole gas heater. The velocity of the gas changes little in the tube. There exists a large temperature difference between resistance tube and the gas. An optimized heater structure can increase the efficiency of heat exchanging. To ensure a high efficiency, the length of the resistance tube must be long enough; the larger the center pitch, the higher the exchange efficiency. The suitable diameter (8-12 mm) is also required for the resistance tube.