Air Force Institute of Technology Dr. King's primary area of research has been in the area of fluid dynamics and heat transfer in airbreathing propulsion components, in particular axial flow turbines and compressors. Three facilities have been used for the gathering of experimental data to support this work, the AFIT Turbine Cascade Facility, the AFIT Compressor Cascade Facility, and the Wright Lab Rotating Compressor Facility. In addition, Dr. King has joined a national research effort known as JDAPS, as explained below.
AFIT Turbine Cascade Facility
This facility is an open return, angled wind tunnel for testing high-turning-angle turbine blades arranged in a stacked, linear fashion (cascaded). Subsonic air is drawn through four blades while one instrumented blade is electrically heated by a wrap-around thin metal skin. This facility was designed and built under Dr. King's supervision at the USAF Academy and transported to AFIT in 1988. Project ideas for the facility have been derived from discussions with the Wright Lab Propulsion and Power Directorate (WL/POTC). There have been a total of five masters students who have used the facility for their research. Prior to this year studies in the tunnel have focused on the effects of turbulence on blade heat transfer. A modification suggested by Dr. King last year included the addition of spinning bars upstream of the cascade to simulate the effects of trailing edge blade wakes on blade heat transfer. With the addition of this modification, the AFIT TCF is the only facility in the country producing this type of three dimensional, unsteady effect in turbine cascades. Thesis results from this rig will continue to shape AFIT's and POTC's research direction of the near future. Two conference papers have been published from student theses, with one of these also in preparation for submission to an archival journal.
AFIT Compressor Cascade Facility
This facility is an open-return wind tunnel designed to test airfoil geometry variations, roughness and turbulence effects, and off-design incidence effects on a linear cascade of compressor blades simulating an axial flow compressor stage. Since 1989, Dr. Elrod and Dr. King have been co-principal investigators on a series of studies into the effects of notched trailing edges on compressor blades, an idea originally proposed by the Wright Lab Propulsion and Power Directorate (POTX). This work has involved four masters students (the latest two recently completed in December 1993), and new ideas about the three-dimensional flow patterns in a compressor passage have emerged. Two conference papers and one archival journal publication have been published from student theses. A second archival journal submission is in progress.
Wright Lab Rotating Compressor Facility
This facility is a closed-circuit wind tunnel housing an engine-size, single-stage axial compressor which can be driven at engine rotation speeds. Three recent AFIT projects have involved the characterization of rotating stall, and aerodynamic instability due to mismatched air flow and wheel speed. Signal analysis techniques developed by Dr. King and his students have captured stall precursor signals embedded in low-level pressure transducer signals and helped identify flow phenomena associated with new blade designs developed by WL/POTX. Two conference papers have resulted, with one subsequent submittal to an archival journal. A third conference paper is in preparation. WL/POTX has requested AFIT (Dr. King) to continue his analysis of stall phenomena. Dr. King plans to have constructed a rudimentary, one-stage compressor (or fan) and investigate the stall phenomenon using flow visualization techniques.
Joint Dynamic Airbreathing Propulsion Simulations (JDAPS)
Dr. King has recently joined the JDAPS research effort headed by the USAF Arnold Engineering Development Center (AEDC) and which includes government, university, and industrial participants engaged in developing state-of-the-art simulation (software) technology for airbreathing, turbomachinery-based propulsion systems. Dr. King and his students will focus initially on numerical simulation of multistage compressors aimed at the development of on-line computation of compressor operating maps for use in real-time analysis during compressor testing in the Compressor Research Facility (CRF) located at Wright-Patterson AFB. One master's student (GAE-95D) is currently in progress on this project.
Gortler Vortex Control
With Ph.D. student J. Rothenflue, Dr. King has been investigating the possibility of the control of amplification/attenuation of centrifugally induced (on curved surfaces) vortices through the use of riblets (longitudinal grooves) to select the wavelength of vortex pairs. This research has importance in compressor and turbine aerodynamics and heat transfer. Two submissions have been made to archival journals, with a third to be submitted upon conclusion of the past phase of work. |