Electrostatic Effects on Airborne Particle Deposition in Gas Turbine Engines

Abstract The effects of electrostatics on the deposition of 0–5 µm Arizona Road Dust within a gas turbine hot section were studied. These experiments focused on different cooling methods found in turbine components: impingement cooling jets and double-walled cooling circuits. Particles within a flow can experience tribocharging through collisions with their surroundings: walls of passages and other particles. For the impingement cooling jet, dust was entrained with hot air through a 6.35-mm-diameter pipe at a mean velocity of 57 m/s. The gas temperature ranged from 755 K to 1005 K to test the temperature sensitivity of any electrostatic effects. The dust-laden jet impinges on a charged plate (−12 kV to +12 kV) to form a deposit. The effect of plate charge on the morphological characteristics of the deposit formation was assessed. For the double-walled cooling circuit, a charge (−5 kV to +5 kV) was applied to both the effusion interior and impingement exterior. Dust was entrained in an 810 K flow with a pressure ratio (PR) of 1.03. No significant electrostatic effect was observed for this geometry. These findings were supported by lower-temperature gravity-drop tests through charged parallel plates and a charged cylindrical pipe. The more fundamental tests confirmed that Arizona Road Dust particles tribocharge negatively and are attracted to positive potential surfaces. This effect appears to be augmented at higher temperature. The cylindrical gravity-drop confirmed that electrostatic influence diminishes due to the absence of electric field lines within enclosed geometries.