An Inertial Particle Separator (IPS) is a non-barrier system installed at the inlet of a gas turbine to mitigate effects of particulate ingestion on the engine. This study presents experimental data for a wide range of flow path designs and test dusts. The experiments were conducted in a bifurcating wind tunnel with a rectangular cross-section and aggressive flow turning, injecting particles with a range of sizes and shapes. A new flow path geometry exhibited higher particle separation efficiency for a variety of test dusts over a range of operating conditions, including off-design cases. The new flow path used a smaller scavenge channel than previous designs in order to reduce flow separation, though not so small as to stop large particles from entering. Data postprocessing highlights the importance of particle Stokes number, scavenge mass flow ratio, and scavenge flow expansion ratio as key parameters in IPS design.

An Inertial Particle Separator (IPS) can help reduce performance degradation of gas turbine engines used in aircraft when operating in dusty environments. In particular, an IPS geometry uses flow curvature to separate particles from the core flow path, so they are ideally fully directed into the scavenge flow path. To better understand the multiphase flow physics and performance of an IPS system, an axisymmetric-sector vertical bifurcated wind tunnel was developed and tested. This wind tunnel was designed to emulate the fluid and particle physics associated with the axisymmetric flow bifurcation for typical operational conditions. The wind tunnel employs a 50-degree sector angle to allow optical accessibility combined with a ratio of throat height to throat radius of 0.17. The tunnel uses a geometry representative of typical systems in terms of air flow velocities but with a size of about 40% (based on throat height) relative to full-scale systems. The wind tunnel air flow is achieved with two exhaust blowers and a calibrated control system, which allows for high mass-flow stability and a wide range of flow split ratios between the core and scavenge flows. To characterize the tunnel’s aerodynamic performance, measurements were taken for mass-flow stability and surface flow visualization to investigate corner flows and separation regions. The results indicate that the flow is highly stable and has separation regions qualitatively similar to those seen in 2-D facilities.

Aircraft-mounted gas turbine engines may need to employ a variety of inlet ducts to perform various missions. An inertial particle separator (IPS) is a type of inlet duct that can remove harmful dust and debris from an engine's flow path. The IPS is a bifurcating duct that is designed to remove particles, but it may also cause undesired flow separation. A novel study on such a bifurcating duct at high Reynolds number is undertaken. This is the first study to perform unsteady, three-dimensional simulations of the flow inside an IPS. The improved delayed detached eddy simulation numerical method is applied to a time-resolved experimental S-duct case to ensure the approach is valid. Results showed highly unsteady, separated flow, consistent with experiments. The time-resolved, three-dimensional structure of flow inside an IPS is visualized for the first time.

We demonstrate a novel application of supervised machine learning (ML) models to quantify the size, shape, number density, and distribution parameters of a water spray introduced at a gas turbine inlet. Only a limited set of laser scattering and extinction observations, acquired by pairs of photodetectors and cameras, are required for an accurate output. A phase Doppler particle analyzer as well as a conventional extinction inversion method are used to validate the particle size estimation, with the ML method converging closely to both. By measuring a water spray, where a spherical particle shape can be assumed, these size estimate validations could be made, which would have been difficult for a nonspherical particle measurement. By combining all the estimated parameters, the liquid volume fraction as well as the liquid flow rate is estimated and compared to a traceable ultrasonic flowmeter. To our knowledge, this is the first in situ condensation load measurement made at a gas turbine inlet without prior calibration. The ML approach is able to accurately estimate the liquid flow rate, with the majority of the estimates lying within the uncertainty bounds of the flowmeter and a root-mean-square difference of 0.8 L h(-1) or 7.4%. Estimating the liquid flow rate using all the particle parameters demonstrates the method's robustness and readiness for accurately measuring even nonspherical particles. The low number of required optical observations also makes this technique attractive for more generalized inlet particle measurements including sand, dust, and volcanic ash, in addition to condensation.

Natural particles, such as sand and dust, often have irregular, angular shapes without porosity. Such sedimentary particles can have a significantly different drag coefficients than spherical particles, and a robust drag coefficient model is needed to accurately predict their trajectory in multiphase flows. Such a model requires quantitative characterization of their shape. Herein it is shown that the Corey Shape Factor is a suitable parameter to characterize particle drag coefficient for a wide variety of particles with Reynolds numbers up to 2 x 10(5). This is accomplished by investigating the shape effects for both the Stokes drag regime and for the Newton drag regime to provide a comprehensive and validated drag model for irregular angular particles as a function of Corey Shape Factor. In addition, the shape of ISO 12103 Arizona Road Dust is measured (for the first time) to allow use of the corresponding drag model. (c) 2020 Elsevier B.V. All rights reserved.

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 brownout conditions so as to increase engine life. Typically, IPS systems have lower engine power losses than alternative engine inlet filtration technologies. The present study investigates the effect of IPS particle removal and power losses as a function of scavenge leg geometry. Performance was evaluated based on particle separation efficiency, particle image velocimetry, and surface flow visualization, as well as power loss and mass flow rate variations. Of the various scavenge geometries considered, it was found that flow constriction with a hub-side ramp most improved separation efficiency, while also stabilizing mass flow rates and generally reducing power loss. This is attributed to a reduction in the level of flow separation by the addition of a favorable pressure gradient and geometry changes downstream of the attached flow region.

The application of Six Sigma design methods to an inlet particle separator is presented in this paper. As stated in the book “Design for Six Sigma Memory Jogger” Six Sigma is a collection of methods that guides “developing new processes, products, and services that meet customer requirements upon the initial offering”. The process involves obtaining input from relevant sources on the technical requirements. The information is then prioritized to facilitate decisions on the most important design parameters and figures of merit. The decisions are used to formulate the design/optimization problem. The commercially available Isight software is used to perform the design/optimization study. The analysis involves the use of twodimensional geometry generation, mesh generation and flow analysis for each configuration studied. Once the flow field has been established a discrete particle model is run to determine the sand separation efficiencies for each particle size. The process is repeated using a design of experiments approach. Due to the length of time required to complete one configuration, a response surface approach is used to perform optimization within the complete design space.