Effects of coolant parameters on low cycle fatigue life of milled channel nozzle

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-dimensional effect, with the biggish strain mainly distributed in the liner region connected with rib, and the maximum residual strain lying in the middle of the nozzle, which is consistent with the low cycle fatigue life distribution. 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 280 K.