Numerical Simulation of Impingement/effusion Cooling With Additively Manufactured Lattice Structure

Gas Turbine is the common parts in power generation and aviation engine due to high efficiency. As the gas turbine is going to be more high efficiency, this requires higher turbine inlet temperature. Thus, new cooling technology is needed to protect from failures for the hot components. The components that exposed at high thermal load, the impingement/effusion cooling is commonly used, but for the constraint of manufacturing problems, application of impingement/effusion cooling has a limit to apply advanced cooling technology. Nevertheless, the fabrication technology is being more advanced, especially the concentration of research of metal additive manufacturing (AM) technology is more highly. So, the gas turbine cooling design that limited by conventional casting fabrication getting freer from the limitation. However, when building with AM, supports are necessary for the preventing components from collapsing while building, but hard to remove from inside of the fabricated components. The lattice structure solves the support problem for the cavity of the impingement/effusion cooling and does not require and remove the support inside of the cavity. Besides, the lattice can improve cooling effectiveness, such as pin-fin in the impingement/effusion cooling. Therefore, tetrahedral and cube lattice is suggested, conjugate heat transfer simulation was conducted to obtain overall cooling effectiveness and flow field. For the Biot number similarity with the actual gas turbine, the material of the plate was chosen Duraform PA® (Nylon 12), which has thermal conductivity is 0.7 W/mK. The geometry of the numerical model consists of two plates and a lattice structure in the cavity, and impingement and effusion holes are on each plate. Both lattices have the same area of contact with lattice and target plate (footprint area). At the target plate, a jet from the impingement hole is impinging to the target plate, and after the collision, the wall jet interacts with adjacent jets. The tetrahedral lattice's footprint zones are located in the center of the interacting zone, and this structure disturbs the interaction of the wall jet then the target plate around the structure's overall cooling effectiveness is relatively high due to conduction from the structure. On the other hand, the cube lattice has almost the same footprint area with tetrahedral lattice, but overall cooling effectiveness is relatively low than the tetrahedral lattice. Therefore, the location of the lattice footprint zone is the main parameter of the impingement/effusion cooling with a lattice structure.