A Parametric Study of Inertial Particle Separator Geometry

An Inertial Particle Separator (IPS) is a particulate removal device typically installed at the inlet of a gas turbine to mitigate effects of sand ingestion on the engine. This system can minimize particulate ingestion during helicopter landings in austere brown-out conditions so as to increase engine life. Typically, IPS systems have lower engine power losses than alternative engine inlet filtration technologies.
The present studies investigated a variety of novel IPS geometries. Tests were conducted on a fundamental two-dimensional experimental facility that allows optical access. Geometries were evaluated using a variety of performance criteria. Of primary import is particle separation efficiency which measures the effectiveness of the system at removing particulate from the core engine flow stream. The separation efficiency of a particular IPS configuration is reliant in part on the characteristics of the flowfield, especially for finer particulate. Low scavenge air mass flow fractions are desirable, as it is directly related to the amount of power diverted from the engine to power the IPS. However, lowering scavenge mass flow fraction increases rates of flow separation and instability, leading to lost particle separation efficiency. There is a lack of available experimental data for IPS geometries designed to operate effectively at these low scavenge mass flow fractions.
Modifications from a baseline geometry were made to the scavenge leg and Outer Surface Geometry (OSG). Performance was evaluated based on particle separation efficiency, Particle Image Velocimetry (PIV), surface flow visualization, first order predictive methods, as well as power loss and mass flow rate variations. These experiments showed that reductions in the scavenge channel height were effective at increasing separation efficiency at low scavenge mass flow fraction. Additionally, these modifications successfully reduced flow instability and demonstrated a link between flow separation and particle separation efficiency. The present studies provide comprehensive empirical data to guide future development of IPS geometries specifically optimized to perform effectively at low power levels.