IMPACT OF TURBULENCE MODELING ON FLUID/SOLID HEAT TRANSFER INSIDE INDUSTRIAL AUTOCLAVES

This work is centred on the analysis of the impact of different turbulence modeling approaches on the fluid/solid heat exchange inside a commercial size autoclave. This project proposes itself to be a first step towards the optimization of the turbulent flow inside this kind of machinery to improve the curing treatment of Carbon-Fiber Reinforced Plastics (CFRP). The setup of the CFD simulations includes the presence of a metallic sample object inside the autoclave, where air will be recirculated with velocity, pressure and temperature typically adopted for this type of treatments. The analysis takes advantage of parallel CFD simulations, conducted by using the open-source software openFOAM v2106. Two turbulence models have been adopted: one is the well-known Reynolds-Average Navier-Stokes approach (RANS), which is currently used to model the turbulence inside this type of machinery. The second one is the Delayed Detached Eddy Simulations (DDES), which allows the full resolution of the majority of turbulent scales around the sample object. First, we propose the difference between the local heat flux distribution at the air/solid interface computed by using RANS and DDES, next we analyse the overall heat flux entering the sample object: the resolution of the turbulent scales does not influence the local heat flux only, but also the overall heat flux entering the object; an average increase of 35% is reported when the velocity fluctuations are neglected. Future steps of the research foresee the analysis of the heat flux and temperature distributions on the surface of realistic shapes and common-use CFRP. Afterwards, the autoclave design will be optimized by adding multiple inlets and aerodynamic devices to guarantee a more homogeneous heat flux distribution on the surface of realistic shapes of actual CFRP.