Deposition of sand particles on a solid substrate in a high-temperature subsonic flow

Abstract

Ingestion of sand particles into gas turbine engines has been observed to cause damage to engine components and in some cases leads to catastrophic failure. One such mechanism responsible for engine failure occurs through the deposition of molten particles on the turbine blades in the hot-section of the engine. The deposited material reacts chemically and penetrates the thermal barrier coating (TBC) on the turbines blades eventually damaging them. As high-efficiency engines are being pursued, the peak operating temperatures are bound to increase well above the softening temperature of the solid particulates. In this work, we investigate the deposition of sand particles on a solid substrate using two-way coupled Euler-Lagrange simulations. In these simulations, hot gas at 1700 K is issued from a circular inlet at Mach 0.3. Simultaneously, spherical sand particles, modeled after the Calcia-Magnesia-Alumino-Silicates(CMAS), are injected at a constant mass flow rate of 1 gram per minute. The deposition of these particles on a solid substrate, placed 20 cm away from the inlet along the axial direction, is investigated. These simulations are modeled after the experiments performed using the Hot-Particle Ingestion Rig (HPIR) facility at the Army Research Laboratory. The particle rebound and deposition model given by Bons et al. ["A simple physics-based model for particle rebound and deposition in turbomachinery." Journal of Turbomachinery 139.8 (2017)] is implemented and used in this work. Euler-Lagrange simulations are carried out for three different synthetic sand particles (CMAS, AFRL 02 and AFRL 03). To isolate the effects of Stokes number mono-dispersed particles are injected with a Gaussian spatial distribution. The effect of material properties and particle size on particle properties such * Address all correspondence to this author at rkoneru[at]umd.edu.as number of particle depositions, rebound velocity and coefficient of restitution are investigated. NOMENCLATURETBC Thermal Barrier Coating. EBC Environmental Barrier Coating. YSZ Yttria stabilized Zirconia. CMAS Calcia-Magnesia-Alumino-Silicate. AFRL Air Force Research Laboratory. HPIR Hot Particulate Ingestion Rig. (.) p Particle property. (.) s Surface/coupon property. V n1 Impact velocity in the normal direction. V n2 Rebound velocity in the normal direction. V n1crit Critical velocity of impact in the normal direction. ν Poisson's ratio.