DATE:                         4.18.24 

TIME:                          4:00pm

LOCATION:             31-270 

SPEAKER:                Professor Jeffrey Bons, The Ohio State University

TOPIC:                       Variable Cycle Gas Turbines Enabled by Active Fluidic Control of the Nozzle Guide Vane Throat

ABSTRACT: 

Experiments were conducted to validate the building blocks of a fluidically controlled variable area turbine concept that uses injected high-pressure air to effectively reduce the choke area of the turbine engine. Preliminary results from a simple quasi-1D converging-diverging nozzle, with an injection flow slot upstream of the throat, showed a 2.2:1 ratio between throttled mass flow rate and injected mass flow rate at a constant nozzle pressure ratio. The penetration of the injection flow and corresponding reduction in the primary flow streamtube were successfully visualized using a shadowgraph technique. Building on this success, a representative single passage nozzle guide vane transonic flowpath was constructed to demonstrate feasibility beyond the quasi-1D converging-diverging nozzle. Both secondary slot blowing from the vane pressure surface and vane suction surface just upstream of the passage throat again successfully reduced primary flow. In addition, fluidic vortex generators were used on the adjacent suction surface to reduce total pressure loss and further throttle the primary flow. A simplified model was developed to assess the driving design factors that influence the blocked flow fraction and throttling effectiveness of the actuators. The model approximates slot injection using a simplified stream tube analysis, neglecting mixing with the primary passage flow. Throttling performance is predicted for fluidic actuators with different widths, orientations, streamwise locations, and pressure ratios. Two-dimensional CFD of injection in the nozzle guide vane passage reported strong agreement with the results of the simple model using the variable width duct. This model has potential application for optimizing fluidic VAT throttling designs while saving on the cost of high-fidelity testing and production of these configurations. 

BIO:
Dr. Jeffrey Bons received his BS, MS, and PhD at MIT in Course 16 (’88, ’90, ’97).  In addition to his 12 years of active duty service as an officer in the U.S. Air Force, Dr. Bons has been a faculty member for 27 years: 5 years at the Air Force Institute of Technology (AFIT) in Dayton, OH, 5 years at Brigham Young University in Provo, UT, and 17 years at The Ohio State University in Columbus, OH.  His research specialties include gas turbine propulsion (particularly hot section performance in particle-laden environments) and aero applications of active flow control.  He is a fellow of ASME and an associate fellow of AIAA.  Dr. Bons and his wife are the parents of 6 children, grandparents of 10 and live in Dublin, Ohio.