Over the last decade, the Turbomachinery and Propulsion Research Laboratory at Virginia Tech has researched, invented, developed, computationally analyzed, experimentally tested, and improved turbofan engine inlet distortion generators.  This effort began with modernizing and improving inlet total pressure distortion screens originally conceived over half a century ago; continued with the invention of inlet swirl distortion generators (StreamVanes^TM^) made possible only through advances in modern additive manufacturing technology; and, thus far, has culminated in a novel combined device (ScreenVanes^TM^) capable of simulating realistic flight conditions of coupled inlet total pressure and swirl distortion in a ground-test turbofan engine research platform.

 

As airframe/engine integration continues to shape the future of aviation, turbofan engines and ducted propulsors will be subjected to increasingly higher demands for operability in non-uniform inlet flow.  Embedded engines suffer from losses in potential energy due to fluid directional changes and drag within the three-dimensional inlet ducts directing incoming air to the engine.  As a contribution to advancing turbofan engine ground test technology in support of propulsion system integration, the invention of the ScreenVane coupled total pressure and swirl distortion generator enables researchers, engine designers, and airframers to understand interactions between complex inlet distortion profiles and the turbomachinery ingesting the flow.

 

The present research focuses on the methodology development, computational analysis, and experimental validation of a novel simultaneous inlet total pressure and swirl distortion generator.  A case study involving a single bend S-duct inlet distortion profile demonstrates the ability to generate a high-fidelity profile simulation, yet outlines a design process sufficiently generic for application to any arbitrary inlet or distortion.  A computational fluid dynamics simulation of the S-duct inlet provided the target profile extracted at the aerodynamic interface plane.  Next, utilizing a method of inverse propagation, the planar distortion profile was propagated upstream to yield a flow field that could be manufactured by a distortion generator adequately isolated from turbomachinery effects.  The individual total pressure distortion screen and swirl distortion StreamVane components were then designed and computationally analyzed.  Upon successful reproduction of the S-duct inlet distortion profile, experimental hardware was fabricated and tested to validate the ScreenVane device.

 

Comparison of the S-duct manufactured distortion and the ScreenVane manufactured distortion was used as the primary metric for profile replication success.  Results from the computational analysis indicated excellent agreement in distortion pattern shape, extent, and intensity with full-field total pressure recovery and swirl angle profiles matching within approximately 1.00% and 2.5°, respectively.  Furthermore, experimental validation of the device indicated nearly identical results of full-field total pressure recovery and swirl angle profile replication of approximately 1.25% and 3.0°, respectively.  The investigation concluded that not only was the ScreenVane device capable of accurately simulating a complex inlet distortion profile, but also produced a viable device for full-scale turbofan engine ground test.


Development, Analysis, and Validation of a Simultaneous Inlet Total Pressure and Swirl Distortion Generator

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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