Deposition in Gas Turbine Hot Section Components
Abstract
The ingestion of fine particulate in gas turbines is an issue of increasing importance in the 21st century due to two competing trends: (1) in pursuit of higher efficiency, engine manufacturers are increasing peak temperatures well above the softening temperature of airborne particles and (2) air quality in currently active military theaters (Far East, Middle East, and Africa) is very poor. The confluence of these two trends has led to reduced aircraft availability due to unscheduled maintenanceand even aircraft/personnel loss due to in-flight engine failure. Particles that make it into the turbine flowpath can become molten and create deposits that clog cooling paths and restrict critical nozzle guide vane choke area resulting in reduced massflow and compressor surge. Due to the cost of diagnosing and correcting this problem with full-scale engine testing, there has been growing interest in the ability to model particle entrainment, rebound, and deposition computationally. Computational models must be grounded with a solid physical understanding of the relevant phenomena in order to be useful over a wide range of operating conditions and engine types. In practice, this physical understanding comes from careful experimental campaigns that isolate individual mechanisms and provide a means tovalidate CFD models. While significant progress has been made with predicting particle entrainment (trajectories) and rebound, two critical areas of study are woefully lacking in experimental data, namely: (1) internal (cooling passage) deposition at elevated pressures typical of gas turbines and (2) externaldeposition at temperatures in excess of the particle melting temperature.The goal of the proposed research is to acquire detailed experimental data documenting deposition phenomena that are unique to the high temperature, high pressure environment of the aero-engine hot section. The experiments will be conducted using two unique, state-of-the-art deposition facilities located at the Aerospace Research Center at OSU. The first test facility is capable of deposition testing of internal turbine cooling components at pressures up to 21atm. An inductance heater is used to provide the appropriate external thermal boundary condition while the elevated coolant temperature is attained with a 36kW heat exchanger. Test articles will include: impingement cooling only, effusion coolingonly, and doubled-walled impingement/effusion cooling. The second test facility provides a hot gas stream, seeded with fine particulate, to impact a cooled target specimen at impingement angles from 10-90??. This facility is designed to operate at gas temperatures approaching 2000K, a region of the design space where there is no publicly-available deposition data. Test campaigns in this facility will explorethe effect of internal as well film cooling at these elevated gas temperatures, as well as various high temperature coatings (TBC). Both the high pressure and high temperature facilities will acquire data with different dust compositions and size distributions for the broadest applicability possible.The experimental effort will be coupled with a physics-based modeling effort to incorporate the results into a predictive capability. This enhanced deposition model could then open the door todeposition mitigation strategies as well as innovative cooling technologies that enhance efficiency while not sacrificing operability. This proposal constitutes a comprehensive study to provide the aero-engine community with the relevant data and modeling necessary to meet the US Navy???s need for high engineavailability and operability in hazardous particle-laden air.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 26, 2018
- Source ID
- N000141812581
Entities
People
- Jeffrey Bons
Organizations
- Office of Naval Research
- Ohio State University
- United States Navy