Scientists from St.-Petersburg Polytechnical University named after Peter the Great developed innovative systems fir cooling gas-turbine blades based on gyroid lattice structures. These structures were created using additive technology — layered laser alloyage of metal powders.
Gas turbines are the heart of power installations, and their efficiency is directly linked with the temperature of gas at the inlet of the turbine. Raising this temperature by every 100 °C gives approximately 2–3 % increment in efficiency, but at the same time it creates extreme thermal and mechanical loads on the material of the blades. Hence, it is the cooling system that determines the durability and reliability of a turbine.
Gyroid structure resembling complicated biological systems feature unique properties: big surface area, even distribution of thermal flow and ability to dampen the vibration. For a long time they could not be used due to complicated geometry, but 3D printing allows for easier production of such structures.
In the course of their study the researchers used the 3D printer to print out samples of channels with gyroid insertion elements and tested them in aerodynamic installation. The comparison against classic smooth channels showed impressive results: the heat transfer coefficient grew 8.3 times, and the wall cooling range almost doubled (grew 1.93 times). In addition, the temperature was distributed more evenly decreasing the risk of local overheating and of fractures appearing.
High efficiency was achieved due to a special shape of gyroid — the minimal 3D surface with long-sweep bends and developed area. Such structures create turbulence of the flow facilitating heat transfer, but at the same time increasing hydraulic resistance. Simulations and tests showed: optimal results may be achieved if the lattice has medium density; then cooling is improved significantly, and pressure loss remains at allowable level.
To describe identified interdependencies mathematical models were built based on polynomial regression. Their accuracy exceeded 96 % allowing for forecasting the parameters of future structures without lengthy and costly calculations. The experiment data confirmed the correctness of the approach: the divergence between the simulation and the tests made not more than 1.5 %.
At the final stage of the study the team presented the prototype of gas-turbine blade with integrated gyroid channels manufactured using the selective laser alloyage method. The first tests showed that the new cooling system featured higher efficiency vs the old one, requiring less air consumption at the same time.
This research opens the way for creating new generation turbines for energy and aviation sectors. Now it is possible to operate under higher temperatures, improving the efficiency of installation and decreasing the specific consumption of fuel.
