重复频率激光辐照柱壳的加热效率

Heating Efficiency of Repetitive Frequency Intensity Laser-Irradiated Cylinder

基于傅里叶热传导方程,利用积分变换法推导出连续激光和重复频率(RF)激光束辐照圆柱壳体温度分布的三维近似解析解,给出了重复频率激光相对于连续激光的加热效率表达式。在此基础上,数值计算了45#钢壳体在不同重复频率和旋转角速度下的温升,分析了激光参数和材料热特性对加热效率的影响。研究结果表明,重复频率激光加热壳体的加热效率小于连续激光,随着重复频率的增加而增加并逐渐接近连续激光,且主要取决于两个无量纲参数(Da=4ατ/r20,m=fLτ)。对于旋转壳体,环向温度呈周期性振荡分布,其振荡特性取决于激光的重复频率fL和壳体的旋转频率fR的匹配情况,fH=fL/fR越大,振荡的幅度越小,越接近连续激光辐照。研究结果对目标抗激光旋转防护设计具有应用价值。

An analytical solution for the temperature profiles that continue wave （CW） laser and repetitive frequency （RF） laser irradiating static cylinder and rotating cylinder is obtained by utilizing a integral transform method. By introducing the definition of heating efficiency, an approximate analytical expression is given. The results show that the main factors affecting heating efficiency are two dimensinless parameter： Da=4ατ/r0^2 （ratio of heat diffusion length in iradiated time and laser facula radius） and m =fLτ （irradiated pulse number）. The higher the laser pulse frequency is, the higher the efficiency of laser heating metal until the efficiency is approach to the CW laser case. In addition, the temperature distributions are calculated by numerical simulation in a rotating cylinder. The numerical results show that the loop temperature distributions present a oscillating characterization depended on the RF-laser frequencies and rotating velocities. The higher the ratio of laser pulse frequencies to rotating velocities is, the smaller the oscillating amplitude of the loop temperature distribution until the loop temperature distribution is approach to the CW laser case. These results can be applied to rotating-heatproof-design for anti-laser damage.