TPMS Turbojet Precooler Design Methodology and Case Study

Abstract Turbojet precoolers can benefit from additively manufactured triply periodic minimal surfaces (TPMS). Although literature has quantified heat exchanger performance improvements with specifically gyroid or diamond lattice structures and how to utilize optimization frameworks, pressure loss and heat-transfer correlations appear to be geometry-specific and a precooler design methodology is not apparent. Parametric steady-RANS CFD studies that employed the SST turbulence model with a zero-thickness shell interface were conducted on 50-50 and 80-20 volume ratio cross-flow gyroid and diamond arrays where air was the hot fluid and hydrogen gas was the cold fluid between the Reynolds numbers of 5,000 and 2e5. Better fits for drag coefficient and Nusselt number occurred when tortuosity and viscosity ratio were included as independent parameters. Given compressor inlet temperature and H2 pressure loss constraints, a methodology was proposed to determine the optimal volume ratio for an unit cell. A cross-flow precooler case study showed that weight was minimum as TPMS cell size Δx decreased whereas pressure loss was minimum at Δx = 4.5cm.