冷却流道布局对铣槽喷管低周疲劳寿命的影响

Effects of Coolant Passage Layout on Low Cycle Fatigue Life of Milled Channel Nozzle

为了研究不同的冷却流道布局对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响应和低周疲劳寿命的影响,采用有限体积流—热耦合计算方法、非线性有限元热—结构耦合分析方法和局部应变法对比分析了冷却剂单向逆流、单向顺流和先顺向流动再逆向流动的来回流三种流道布局方案。计算结果表明,铣槽喷管内衬最严重的节点应变主要发生在喷管前部内衬燃气侧壁面与肋条对称面及槽道对称面相交的危险区域,这也是节点低周疲劳寿命最小的位置;铣槽内衬节点的应变时间历程主要由塑性应变决定,肋条与槽道对称面上内衬节点的热结构响应存在较大差异;采用冷却剂单向逆流布局的铣槽喷管内衬节点应变幅和残余应变最大,导致喷管疲劳使用寿命最短;采用冷却剂单向顺流布局的铣槽喷管内衬节点应变幅和残余应变最小,导致喷管低周疲劳寿命最长;采用冷却剂来回流布局的再生冷却喷管铣槽内衬的热结构响应和疲劳使用寿命均处于上述两者之间,但取消了喷管尾部集合器和外置冷却剂供给管路等易失效的部件。

To investigate the effects of different coolant passage layouts on the thermal-structural re- sponse and low cycle fatigue life of 3D regeneratively cooled channel wall nozzle with high area ratio under cyclic working loads, the finite volume fluid-thermal coupling calculation method, nonlinear finite element thermal-structural coupling analysis method and local strain metJhod were adopted to analyze the coolant backward flow layout, coolant forward flow layout and coolant forward to backward flow layout. Numerical simulation results show that the most serious strain on milled liner of channel wall nozzle mainly occurs at the intersectant regions of liner gas side wall and symmetric planes of rib and channel in the front of nozzle extension, where the minimum node low cycle fatigue life takes place. The node strain history of milled channel nozzle is primarily dominated by the plastic deformation, and the thermal-structural responses be- tween liner nodes, respectively, locating on the symmetric planes of rib and channel exist significant differ- ence. The largest strain amplitude and residual strain during cyclic operation of milled channel nozzle em- ploying coolant backward flow layout result in the shortest fatigue service life. On the contrary, the milled channel nozzle employing coolant forward flow layout with the smallest strain amplitude and residual strain has the longest low cycle fatigue life. Both the thermal-structural response and fatigue life of milled channelnozzle employing coolant forward to backward flow layout fall in between above two nozzles, but it has elimi- nated the easily damaged aft manifold and coolant feed line.