冷喷涂加热器数值模拟

Simulation for gas heater of cold spray system

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.

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.