冷却剂参数对铣槽喷管低周疲劳寿命的影响

Effects of Coolant Parameters on Low Cycle Fatigue Life of Milled Channel Nozzle

采用有限体积流固耦合计算方法、非线性有限元热结构耦合分析方法和局部应变法研究大面积比铣槽喷管三维再生冷却槽道在循环工作条件下的热结构变形与低周疲劳寿命,并对比分析了冷却剂质量流量与入口温度对铣槽喷管疲劳使用寿命的影响。计算结果表明,铣槽喷管热结构响应呈现复杂的三维效应,应变较大位置主要分布在与肋连接的内衬区域,喷管中部的残余应变量最大;冷却槽道低周疲劳寿命分布和热结构响应基本一致,最小寿命位于喷管中部与肋相连的内衬区域燃气侧;随冷却剂质量流量增加,铣槽喷管低周疲劳寿命不断提高;随冷却剂入口温度增加喷管尾部低周疲劳寿命值不断降低,而喷管中前部的低周疲劳寿命值却不断提高,当冷却剂入口温度为280K左右时,本文的铣槽喷管总体使用寿命达到最大。

The finite volume fluid-solid coupling calculation method, nonlinear finite element thermal- structural coupling analysis method and local strain method were adopted to investigate the thermal-structural deformation and low cycle fatigue life of three-dimensional regenerative cooling channel for milled channel nozzle with high area ratio under cyclic working loads, and parametric studies were carried out to estimate the effects of coolant mass flow and inlet temperature on the nozzle fatigue service life. Numerical simulation results show that the thermal-structural response of milled channel nozzle appears the complex three-dimen- sional effect, with the biggish strain mainly distributed in the liner region connected with rib, and the maxi- mum residual strain lying in the middle of the nozzle, which is consistent with the low cycle fatigue life dis- tribution. Hence, the minimum service life occurs at the liner gas side joining with rib in the nozzle middle. While the coolant mass flow increases, the low cycle fatigue life of milled channel nozzle enhances continuously. However, with the rise of coolant inlet temperature the fatigue life of the nozzle afterbody decreases gradually, but yet the fatigue life in the middle and front of the nozzle grows up persistently. To be specific, the optimal general service life of milled channel nozzle in this work occurs at coolant inlet temperature approximately 280K.