Through the 3D printing process, a specific surface finish and channel size can be formed to improve fluid flow through the channel and improve heat transfer in the channel. A rougher finish can be achieved by increasing the laser scanning speed or the thickness of the powder layer, and a smoother finish can be achieved by reducing the laser scanning speed or the thickness of the powder layer. You can also change the scan path or laser power to change the surface finish of a specific area.
This opens up new ideas for the design of parts of a gas turbine that need to be cooled. Recently, according to the patent "plate-shaped structural component of a gas turbine" obtained by Rolls-Royce, Rolls-Royce uses 3D printing of gas turbine plate-shaped structural components to cool The air holes are arranged on the structural components to obtain an optimized cooling effect of the gas turbine components.
According to Rolls-Royce's invention patent, an integrally connected support body is arranged between the side bar and the base body. The support body has a triangular cross section and has multiple slit-shaped grooves. Through additive manufacturing, the wall thickness of the substrate gradually increases, thus avoiding the possibility of residual stress and crack formation.
The structure of achievement changes
Additive production "change"
A cooling air hole penetrating the base is arranged in each slit-shaped recess, and each slit-shaped recess can be geometrically designed in a suitable manner. The width of the recesses and the corresponding remaining width of the support body in the area between the recesses can also be adjusted according to the geometry of the structural component, just like the size and geometry of the cooling air holes. It is also possible to provide a plurality of cooling air holes in the groove. 3D printing-additive manufacturing brings great flexibility in the realization of geometric appearance.
Due to the additional manufacturing flexibility provided by the 3D printing-additive manufacturing method, the cooling hole can be designed differently along its length, such as the possibility of changing its cross section. The advantage of such a design is that a sufficient amount of cooling air can be guided on the back of the base body of the plate-shaped structural component arranged opposite to the side rod. Due to the choice of variably designing the cooling holes in the longitudinal extension direction, it is also possible to realize arc-shaped or spiral-shaped or coil-shaped cooling air holes, which leads to more effective cooling.
It is also possible to provide a cooling air hole extending through the side rod from the slit-shaped groove, which guides the cooling air out of the recess through the side rod. The minimum cross-section of the additional cooling air hole is present at or adjacent to the entrance of the side rod.
Therefore, through the additional cooling air holes formed in the side bars of the plate-shaped structural component, or through the combination of the additional cooling air holes of the side bars and the cooling air holes through the base, it is possible to form only through the slit-shaped recesses or through Cooling air holes in the base of the plate-shaped structural component realize cooling in the side bar area of the plate-shaped structural component.
In Rolls-Royce's patent, the recess is configured to be symmetrical to the center plane of the cooling air hole, which makes the stress distribution uniform in the area of the recess and the adjacent area of the support. In addition, the supply of cooling air to the cooling air holes is optimized.
As mentioned by King Xiaoyan of ACAM in the "3D Printing Powered Power Equipment Development Report", in order to simplify the understanding of the application logic of 3D printing in power parts, the development requirements of power equipment can be summarized as bright spots: strong explosive power and high safety. 3D printing releases the freedom of design and manufacturing. It improves the kinetic energy of power equipment by optimizing the mixing ratio of fuel and air; on the other hand, 3D printing cooling channels or copper metal improves the fast heat dissipation performance of power equipment. Get higher security.
Rolls-Royce's patent "plate-shaped structural component of a gas turbine" realizes the optimization of the cooling effect by arranging various air holes of different shapes on the structural parts, which is precisely the use of 3D printing to improve the safety of power equipment The advantages of sex and stability.
Hay Think Review
With the deepening of the application of additive manufacturing technology, we see that the cooling function is "integrated" into various parts everywhere, not just the structural parts mentioned in the Rolls-Royce patent. Including some functional components, such as the integrated gearbox housing with integrated heat exchanger developed by GE. This changes the previous gas turbine engine heat exchanger away from the accessory gearbox and requires a separate fluid circulation pipeline to supply oil to the heat exchanger. Status. In the past, each pipeline required additional component storage, and brought additional assembly and costs. In addition, the possibility of leakage increases, and when the fluid is transferred to a remote heat exchanger, the fluid may lose a large amount of thermal energy.
Through 3D printing, not only can the gearbox and heat exchanger be manufactured in an integrated structure, but also a very thin wall thickness can be achieved. In the integrated gearbox housing with integrated heat exchanger developed by GE, at least one heat exchange wall Has a thickness of less than 4 mm.
More often, the most important factor limiting the development of 3D printing is people's imagination. With cooling that can be integrated everywhere, 3D printing has undoubtedly opened a door for people to change the current product design.