The Development of Innovative Methods for Erosion Testing a Russian Coating on GE T64 Gas Turbine Engine Compressor Blades

Abstract

The US Navy became aware of a Russian erosion-resistant compressor coating in 1991. The coating was being applied to compressor airfoils on the TV2-117 engine (MI-8 helicopter). Performance data obtained from the Russian coating company showed greatly improved erosion resistance, leading to better engine performance and longer time-on-wing. A proposal was sent to the Foreign Comparative Testing (FCT) office to evaluate the coating for US Navy engines operating in sandy environments. The project was approved and funded in 1997. It was determined that the high-speed erosion chamber at the University of Cincinnati would provide the optimum testing environment for the program. The test articles consisted of a bare blade and a coated blade. Testing conditions required 10 micron silica sand impinging upon the blades at 700 feet per second (fps). Data was collected until the bare blade reached the chord reject criteria. Testing continued until the coated blade reached failure as well. It was found that the coating improved the overall blade life by 300–500%. A method was developed to measure the eroded blades at certain points to determine the real or “effective” chord at any point during the testing. This project demonstrated the need for innovative gauging techniques in order to understand the actual effects of erosion on compressor blades.

Solid particle erosion mechanisms of protective coatings for aerospace applications

“…The Cr-Si-N coating with C Si = 11.6 at.% presents a texture change from (111) to (200), indicative of coating densification because (111) textured coatings typically possess a more opened structure, with more voids between the columns [229]. The important decrease of d g combined with the change in texture seems to indicate that for this latter coating, the limit of solubility has been exceeded and that segregation of SiN x around CrN grains has occurred, changing the growth mechanism [4][5][6][7][8]. This nanostructural change resulting in microstructural densification seems to lead to an increased H v with a related decrease in ER 90 .…”

“…A full engine test conducted by the US Navy [6], in conjunction with the University of Cincinnati, showed the highly protective nature of the soviet developed SPE protective coatings based on a Ti/TiN multilayer structure. In that study, half of the compressor blades were coated and after more than 7 kg of ingested sand, these were relatively unworn when compared to the uncoated blades (Figure 1.3).…”

Mechanisms of Water Droplets Deposition on Turbine Blade Surfaces and Erosion Wear Effects

“…In works of Hamed et al (2004), Kline and Simpson (2004), and Wang et al (2014) is found that degree of erosion is a function of the angle at which the fluid droplets enter in the inter-blade passage, their speed and size.…”

Performance Metrics and Experimental Testing of Erosion-Resistant Compressor Blade Coatings

“…Currently, test methods for compressor coating evaluation using realistic conditions have been minimal. Linear cascade testing of 3-4 stationary coated blades has also been conducted: Klein and Simpson [5] and Tabakoff and Mason [6]. How ever, this is very expensive and impractical for most organizations to carry out.…”