Erosion predictions and measurements of high-temperature coatings and superalloys used in turbomachines

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:6840140

Metwally, M A

Nickel and cobalt superalloys are widely used in the hot section of gas turbines. Protective coatings are used to enhance superalloy erosion-corrosion at elevated temperatures. This investigation is devoted to wind tunnel measurements and analytical prediction of erosion rates and particle rebound characteristics of some newly developed coatings and superalloys. Both erosion rates and particle rebound characteristics are necessary for accurate prediction of erosion in turbomachines. The abrasive particles used in the measurements were coal ash with a weight average diameter of 15 microns. A three components laser Doppler velocimetry system was used to measure both particle impact and rebound velocities over a wide range of impingement angle. Empirical correlations have been developed for the restitution coefficients of both coated and uncoated surfaces. A high temperature erosion test facility was used to measure the erosion rates for the coatings and superalloys. The data was accumulated for wide ranges of the erosion parameters, namely, impingement angle, impact velocity, material temperature, and mass of particles which have the main effects on the material erosion behaviors. Erosion models have been developed to predict the erosion rates of materials whose behavior are ductile. The developed rebound and erosion models were used to predict the particle dynamics and resulting blade surfaces erosion of coal ash particles in a power turbine of an automotive gas turbine engine for both coated and uncoated blade surfaces. The results show the three dimensional particle trajectories through the turbine flow passages and the particle impact locations over the blade surfaces. The predicted counters of erosion rate and its related parameters over the blade surfaces are presented for coated and uncoated blades. In addition an experimental study was conducted which confirmed the locations of the blade surface impacts predicted by the theoretical analysis.

• Research Organization: Cincinnati Univ., OH (United States)
• OSTI ID: 6840140
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330103 -- Internal Combustion Engines-- Turbine
36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ABRASIVES
ALLOYS
COATINGS
COBALT ALLOYS
ENGINES
EQUIPMENT
EROSION
GAS TURBINE ENGINES
HEAT ENGINES
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IMPINGEMENT
INTERNAL COMBUSTION ENGINES
MACHINERY
MATERIALS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
NICKEL ALLOYS
PARTICLES
PERFORMANCE TESTING
PROTECTIVE COATINGS
TESTING
TIME DEPENDENCE
TURBINE BLADES
TURBOMACHINERY
VELOCIMETERS