Study of Solid Particle Erosion on Helicopter Rotor Blades Surfaces

Abstract

In this study, titanium alloy (Ti-4Al-1.5Mn), magnesium alloy (Mg-Li9-A3-Zn3), or aluminum alloy (Al7075-T6) were used to construct the shell model of helicopter rotor blade to study the solid particle erosion of helicopter rotor blades. The erosion resistance of the three materials at different angles of attack (6°, 3°, or 0°) and particle collision speeds (70, 150, or 220 m/s) was examined using the finite volume method, the discrete phase method, and erosion models. In addition, the leading edge of the helicopter blades was coated with two types of bionic anti-erosion coating layers (V- and VC-type), in an attempt to improve erosion resistance at the angles of attack and particle collision speeds given above. The results showed that Ti-4Al-1.5Mn had the best erosion resistance at high speed, followed by Al7075-T6 and Mg-Li9-A3-Zn3. The angle of attack appeared to affect only the surface area of the blade erosion, while the erosion rate was not affected. Finally, the results of this article showed that the V-type bionic coating had better erosion resistance than the VC-type coating at the same impact speeds. The angle of attack did not have a significant effect on the erosion rate of the bionic coating.

Solid Particle Erosion Behaviour and Protective Coatings for Gas Turbine Compressor Blades—A Review

“…The most likely explanation of the process seems to be the existence of forces acting perpendicular to the surface. With aluminium, a ductile material, we see both wear due to repeated deformation (work hardening, followed by surface cracking) which explains the erosion occurring at typical angles of incidence, and we also see cutting wear as described by Finnie [30,53]. Cutting wear is produced by forces working in the surface of the material.…”

“…The firstgeneration of these coatings was fabricated from single phase metal nitrides (e.g., TiN). However, it was found that the added layer did not perform as expected for the normal angle as a result of its high internal stress and low toughness [30][31][32]. This obstacle was afterwards resolved by using the second generation of ERC, which consists of multi-layered structures of metal/ceramic, where the crack generated by the SPE on the exposed surface layer is blocked by the layer that follows it.…”

“…where σ s is blade solidity, β 1 is blade angle, and β m is mean angle of the compressor. It has been shown by Finnie [30,53] that surface wear as a result of SPE will vary with particle speed and direction, and the response of the surface material when the particles impact on it. These factors are inter-related because an erosion roughened surface could enhance the level of turbulence of the fluid and so increase the rate at which material is removed.…”

“…Deformation refers to wear resulting from forces acting perpendicular to the surface. Finnie [30,53] and Bitter [102,106] have confirmed experimentally and analytically that any expression for erosion damage should include: (1) the KE of particles whose line of action is perpendicular to the surface because this is absorbed into the surface and causes wear by deformation, (2) some hard materials, when subject to deformation wear, show a limit to the normal velocity component below which there is no erosion, however the particle's shape may determine this value, (3) cutting wear is related to the component of the particle's KE acting parallel to the surface, (4) for small angles of impact, the particles grazing the surface do not rebound, and all of the KE parallel to the surface contributes to wear by cutting, (5) when the angles of impact are large, the particles tend to experience a relatively large coefficient to restitution and are likely to rebound, with residual KE. Assuming that cutting wear consumes a certain amount of KE to release unit mass of the surface, then with a corresponding deformation factor, ε b , we obtain Equation (19).…”

“…Bitter's equations provide better results at higher angles of impact than Finnie's [30,53]. Four equations are presented.…”