Isokinetic Particle Size and Shape Measurement to Support Gas Turbine Deposition Research
Abstract
The ingestion of fine particulate in gas turbines is an issue of increasing importance in the 21st century due to two competing tren,ds: (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. Th,e confluence of these two trends has led to reduced aircraft availability due to unscheduled maintenance and 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 c,log 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 mod,el particle entrainment, rebound, and deposition computationally. While significant progress has been made with predicting particle,entrainment (trajectories) and rebound, two critical areas of study are lacking in experimental data, namely: (1) internal (cooling,passage) deposition at elevated pressures typical of gas turbines and (2) external deposition at temperatures in excess of the parti,cle melting temperature.Current ONR sponsored research at OSU is acquiring detailed experimental data documenting deposition phenome,na that are unique to the high temperature, high pressure environment of the aero-engine hot section. Experiments are being conducte,d 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 17atm. The second test facility provides,a hot gas stream, seeded with fine particulate, to impact a cooled target specimen at gas temperatures approaching 1800K. Through th,is trail-blazing experimental research, the critical dependence on particle size and shape have become strikingly evident. For inte,rnal (cooling) flows, particle size can make the difference between blockage or erosion whereas for high temperature external (hot g,as path) flows, size indicates ballistic impact and sticking of molten deposits. Particle shape has direct relevance to trajectory,prediction through use of the appropriate non-spherical drag law. Finally, the importance of assessing the particle size distributi,on in-situ has taken center-stage since micron-sized particles at high temperature tend to agglomerate into large structures while, traversing experimental facilities. The intent of this DURP proposal is to acquire an instrument that can be used to monitor parti,cle size distribution and shape real time during deposition experiments using isokinetic extraction of the hot gas stream. The devi,ce identified to do this is the MicroTrac Camsizer X2. The capabilities of this instrument will significantly benefit both the expe,rimental and the computational deposition work currently being conducted at OSU under ONR sponsorship. Current deposition work at O,SU (ARC) with several engine companies (OEM) will also be significantly impacted. These same OEMs produce and maintain aeroengines,for the US Navy, so there will be an indirect DOD benefit there as well.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 05, 2022
- Source ID
- N000142212212
Entities
People
- Jeffrey Bons
Organizations
- Office of Naval Research
- Ohio State University
- United States Navy