Session: 32-08 Flow Control 1

Paper Number: 121643

121643 - A Simplified Injection Model for Variable Area Turbine Fluidic Throttling 

Experiments were conducted on a representative transonic nozzle guide vane passage to evaluate the effectiveness of fluidic actuators in throttling the core mass flow, enabling a variable area turbine (VAT) with no moving parts. These investigations reported nearly a 2 to 1 throttling effectiveness ratio: reducing the core flow by 2 units with only 1 unit of flow injected through a suction surface slot. A simplified model was developed to assess the driving design factors that influence the 3 key throttling performance parameters: blockage, pressure recovery, and flow turning. The model approximates the injected jet using a simplified stream tube analysis, neglecting mixing with the core passage flow. In this way the model can predict the throttling performance of fluidic actuators with different sizes, orientations, and pressure ratios for a nominal channel geometry. The throttling effectiveness was found to be most strongly related to the injection angle. The injector total pressure losses were approximated using a dump diffuser with a simple control volume to mix out the core and injected flow.  This correlated larger injection penetration heights to higher total pressure losses. Changes to the exit angle of the core flow leaving the passage were also predicted. Two-dimensional CFD reported strong agreement with the trends predicted by the simple model. Three-dimensional CFD simulations were also conducted but predicted much higher total pressure losses than the model and the experiments. Modifications were made to the experimental setup to capture pressure measurements across the entire exit flow plane, more accurately representing the three-dimensional effects of the actuators. Further adaptations to the simple model were made by adding compressibility corrections and allowing for variations in velocity across the slot. This refined model has potential application for optimizing fluidic VAT throttling designs and saving on the cost of production and testing of these configurations.

Presenting Author: Jeffrey Bons The Ohio State University

Presenting Author Biography: Dr. Jeffrey Bons is a professor at The Ohio State University in the Department of Mechanical and Aerospace Engineering, leading the Turbine Aerothermodynamics Laboratory. His research interests include heat transfer and fouling in gas turbine engines as well as flow control applications in turbines including suction, blowing, and passive flow control techniques.

Authors:

Alex Spens The Ohio State University
Evan McFadden The Ohio State University
Cole Westrick The Ohio State University
Jeffrey Bons The Ohio State University