Multi-optimization of a specific laminated cooling structure for overall cooling effectiveness and pressure drop

Abstract

The structural optimization of a specific laminated cooling structure is conducted under gas turbine combustor representative aero-thermal conditions, with the aim at improving its overall cooling effectiveness. The optimization procedure is realized by using conjugate heat transfer CFD analysis and radial basis function neural network (RBFNN) surrogated model. For this specific laminated cooling structure, both the thickness of impinging plate (ti) and the thickness of film cooling plate (tf) are all fixed as 0.5 mm. The other geometric parameters including impinging-hole diameter(di), pin-fin diameter(dp), film-hole diameter (df), inner height of double walls (H), streamwise hole-to-hole pitch (S) and spanwise hole-to-hole pitch (P) are selected as the design variables. Two geometric constrains are considered that the total thickness of laminated cooling structure is not bigger than 2 mm, and the minimum clearance between adjacent fins should be bigger than 0.5 mm. By using the current CFD-based optimization methodology, the optimized laminated cooling structures are presented from the given range of possible geometric variables. An optimized laminated cooling structures makes the maximum spatially-averaged overall cooling effectiveness approach to 0.9, and the other for minimum relative total pressure drop can reach 0.17%. Moreover, it is found that the thermal stress has a regularity with the overall cooling effectiveness.