Construction and finite element analysis of SLM-TMF panels

Abstract

The walls of combustion chambers are loaded by the high temperature of the hot gas and the pressure difference between the coolant and the chamber. This causes a failure of the wall over its repeated usage. The Finite Element analysis of a hot gas side of an actively cooled section (the so called TMF panel) taking a real case engine as reference was studied. The need of fast and efficient production in every sector paved the way for a technique called Selective Laser Melting (SLM) which is an additive manufacturing process and combines the advantage of quick production with high design flexibilities. Thus with these advantages the TMF panel is chosen to be produced by this manufacturing process and the objective is to find the number of cycles to failure. Also, a suitable connection technology was found to connect the SLM part with standard counterpart to avoid leakage because of roughness. The unified Chaboche constitutive model's parameters for the material were identified (kinematic and isotropic hardening parameters) for the cyclic analysis for SLM-Inconel 718 at 6 different temperatures (298 K, 723 K, 773 K, 823 K, 873 K and 923 K). The accuracy of the identified parameters was demonstrated by uniaxial strain controlled cyclic analysis for different temperatures which gave good match between the test results and experimental results from literature. The SLM production of the TMF panel has the advantage of flexibility in design but at the same time production cost depends on the volume. Mass flow rate and pressure drop values across separate cooling channels produced by selective laser melting were compared. No blockage was found for 1.3*1.3 mm cooling channels. The half cooling channel + half fin coupled Finite Element analysis based on the reference case (FLPP storable engine) at the nozzle throat (where the loading is reaching its maximum) with symmetry boundary conditions on the centerline of the cooling channel and the centerline of the fin served as the reference for the 3D SLM-TMF panel FE analysis. The panel optimization was carried to match the results of the reference case (FLPP storable engine). The number of cycles to failure was calculated for the FLPP storable engine nozzle throat 2D section and also for the TMF panel before and after optimization by post processing of analysis results. Finally, a cost analysis gave the production cost of a TMF panel which was found out to be less compared with the cost of a conventional TMF panel.