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Guillot S.,Techsburg Inc. | Ng W.F.,Techsburg Inc. | Hamm H.D.,Solar Turbines Inc. | Stang U.E.,Solar Turbines Inc. | Lowe K.T.,Virginia Polytechnic Institute and State University
Proceedings of the ASME Turbo Expo | Year: 2014

Analysis and testing was conducted to optimize an axial diffuser-collector gas turbine exhaust. Two subsonic wind tunnel facilities were designed and built to support this program. A 1/12th scale test rig enabled rapid and efficient evaluation of multiple geometries. This test facility was designed to run continuously at an inlet Mach number of 0.41 and an inlet hydraulic diameter-based Reynolds number of 3.4 × 105. A 1/4th geometric scale test rig was designed and built to validate the data in the 1/12th scale rig. This blow-down rig facilitated testing at a nominally equivalent inlet Mach number, while the Reynolds number was matched to realistic engine conditions via back pressure. Multi-hole pneumatic pressure probes, particle image velocimetry and surface oil flow visualization was deployed in conjunction with computational tools to explore physics-based alterations to the exhaust geometry. The design modifications resulted in a substantial increase in the overall pressure recovery coefficient of +0.07 (experimental result) above the baseline geometry. The optimized performance, first measured at 1/12th scale and obtained using CFD was validated at the full scale Reynolds number. Copyright © 2014 by Solar Turbines Incorporated. Source


Fleming J.,Techsburg Inc. | Langford M.,Techsburg Inc. | Tweedie S.,Techsburg Inc. | Ng W.,Techsburg Inc. | Goossen E.,Honywell Aerospace Electronic Systems
50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition | Year: 2012

Analysis and wind tunnel testing performed as part of a development program for a family of ducted fan unmanned aircraft has generated a significant database of wind tunnel data. These include force and moment data as well as duct lip surface pressures over a range of flight velocities, fan speeds, and vehicle tilt angles. In recognition of the need for a simple, lightweight, and robust air data system for this class of UAV, a study was undertaken to correlate duct pressure data to freestream flow velocities. Sample pressure data and a simple correlation methodology is presented in this paper. Results from this study indicate a strong correlation is present between duct pressures and freestream flow velocities, with very good system sensitivities at flow speeds at and well below 5 knots for the vehicles studied. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. Source


Xue S.,Techsburg Inc. | Guillot S.,Techsburg Inc. | Ng W.F.,Techsburg Inc. | Fleming J.,Techsburg Inc. | And 3 more authors.
Proceedings of the ASME Turbo Expo | Year: 2015

A comprehensive experimental investigation was initiated to evaluate the aerodynamic performance of a gas turbine exhaust diffuser/collector for various strut geometries over a range of inlet angle. The test was conducted on a 1/12th scale rig developed for rapid and accurate evaluation of multiple test configurations. The facility was designed to run continuously at an inlet Mach number of 0.40 and an inlet hydraulic diameter-based Reynolds number of 3.4×105. Multi-hole pneumatic pressure probes and surface oil flow visualization were deployed to ascertain the effects of inlet flow angle and strut geometry. Initial baseline diffuser-only tests with struts omitted showed a weakly increasing trend in pressure recovery with increasing swirl, peaking at 14° before rapidly dropping. Tests on profiled struts showed a similar trend with reduced recovery across the range of swirl and increased recovery drop beyond the peak. Subsequent tests for a full diffuser/collector configuration with profiled struts revealed a rising trend at lower swirl when compared to diffuser-only results, albeit with a reduction in recovery. When tested without struts, the addition of the collector to the diffuser not only reduced the pressure recovery at all angles but also resulted in a shift of the overall characteristic to a peak recovery at a lower value of swirl. The increased operation range associated with the implementation of struts in the full configuration is attributed to the de-swirling effects of the profiled struts. In this case the decreased swirl reduces the flow asymmetry responsible for the reduction in pressure recovery attributed to the formation of a localized reverse-flow vortex near the bottom of the collector. This research indicates that strut setting angle and, to a lesser extent, strut shape can be optimized to provide peak engine performance over a wide range of operation. Copyright © 2015 by ASME. Source


Harrison N.A.,Techsburg Inc. | Anderson J.,Techsburg Inc. | Fleming J.L.,Techsburg Inc. | Ng W.F.,Techsburg Inc.
Journal of Aircraft | Year: 2013

The effectiveness of active flow control for the reduction of flow distortion in boundary layer-ingesting serpentine inlets was examined. The intended purpose of the flow control was to redistribute the ingested low-momentum boundary-layer fluid around the periphery of the diffuser to reduce the flow distortion at the engine face. Avariety of different blowing jet and suction hole configurations were analyzed using computational fluid dynamics, and a subset of these configurations was experimentally validated. Boundary-layer suction alone proved to be ineffective in reducing flow distortion, but suction did enhance the distortion reduction capability of blowing flow control when blowing mass flow rates were greater than 1% of the total inlet mass flow rate. To reduce the demand for bleed air from the engine compressor, it is suggested to augment blowing flow with the flow entrained from the suction holes using an ejector-pump concept. Application of the notional ejector-pump model resulted in a maximum decrease in engine-face distortion of 75% as measured by the DC(60) parameter, as compared with a 28% reduction with blowing alone. Investigations also showed that the most practically effective flow control configurations maintained jet individuality to directly counter duct secondary flows while not combining to form large-scale vortices. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. Source


Fleming J.,Techsburg Inc. | Tweedie S.,Techsburg Inc. | Langford M.,Techsburg Inc. | Ng W.,Techsburg Inc.
International Powered Lift Conference 2010 | Year: 2010

A comprehensive wind tunnel test program in support of the Honeywell T-Hawk™ program was completed in 2009. This test program included a full range of low speed velocity data collection at vehicle pitch angles ranging continuously from pure climb to pure descent. Testing at flow speeds as low as 3 fps was made possible by adapting the plenum chamber of the Virginia Tech Stability Tunnel for testing of the full-scale powered model. Flow survey results prior to testing indicated adequate flow quality was present. Overall quality of force and moment results was very good, and the test approach proved to be a cost effective method of obtaining this type of data. Comparison of plenum data to the standard wind tunnel test section data provided quantitative understanding of blockage and interference effects in the smaller test section. Copyright © 2010 by the American Helicopter Society International, Inc. All rights reserved. Source

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