Deposition of Volcanic Materials in the Hot Sections of Two Gas Turbine Engines

Abstract

This paper reports the results of a series of tests designed to determine the melting and subsequent deposition behavior of volcanic ash cloud materials in modern gas turbine engine combustors and high-pressure turbine vanes. The specific materials tested were Mt. St. Helens ash and a soil blend containing volcanic ash (black scoria) from Twin Mountain, NM. Hot section test systems were built using actual engine combustors, fuel nozzles, ignitors, and high-pressure turbine vanes from an Allison T56 engine can-type combustor and a more modern Pratt and Whitney F-100 engine annular-type combustor. A rather large turbine inlet temperature range can be achieved using these two combustors. The deposition behavior of volcanic materials as well as some of the parameters that govern whether or not these volcanic ash materials melt and are subsequently deposited are discussed.

Air-plasma-sprayed thermal barrier coatings that are resistant to high-temperature attack by glassy deposits

“…The higher engine-operating temperatures enabled by TBCs in aircraft engines are now engendering new materials issues. Specifically, fine sand/ash particles ingested by the engine during operation deposit on the hotter TBC surfaces as molten calciummagnesium-aluminosilicate (CMAS) glass, which penetrates the TBCs, resulting in loss of strain tolerance and premature failure of the TBCs [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Since airborne sand/ash particles are ubiquitous, and there is an increasing demand for higher and higher engine-operating temperatures, the CMAS attack of TBCs (and also environmental barrier coatings or EBCs [15]) is becoming a critical issue in the development of next-generation gas-turbine engines.…”

Operation of Gas Turbine Engines in an Environment Contaminated With Volcanic Ash

“…While only the highlights of these test results obtained using an Allison T56 combustor [21] and a Pratt/Whitney F100 combustor [22][23][24] are presented here, the details are provided in the publicly available references cited.…”

“…Reference [22] provides an extensive study using several different compositions of foreign material to determine the combustor exit temperature necessary to obtain deposition on the nozzle guide vane row. This study was also designed to measure the respective capture ratio for each of the different materials investigated.…”

A novel test approach for plasma-sprayed coatings tested simultaneously under CMAS and thermal gradient cycling conditions

“…In turbine sections where temperatures are below the melting point of these contaminates, they can cause erosive wear, blockage of cooling holes and local spallation [12,13]. However, due to elevated operating temperatures above 1300°C the siliceous debris sticks to the coating, becomes molten and penetrates into the microstructural features.…”