Bojan Vukasinovic      							          home page

'High-Frequency' Flow Control

Traditional approach to the control of shear layer, and separated flows in general, has been focused on the manipulation of global motions that are induced by the fundamental instability modes. However, high-frequency control, where the control frequency is substantially higher than the fundamental (natural) flow frequencies, has recently emerged as a successful control tool for numerous applications related to the mixing enhancement, separation delay, mitigation of optical aberrations, noise suppression, etc. The high-frequency control directly excites the small-scale motions that subsequently alter energy distribution across a wide range of scales.

Flow Diverter

model schematics

Regulation of flow diversion from a primary rectangular channel into a branched secondary duct is investigated experimentally using active flow control. The flow distribution between ducts is effected by controlling the inherent separation at the upstream edge of the compact secondary duct inlet using an integrated spanwise array of the flow control elements. The role of the flow control in the regulation of the diverted flow is assessed in terms of the fraction of the oncoming flow diversion into the secondary duct, along with the reduction in internal flow losses.Objective is to enable a ‘tunable’ fraction of the diverted flow between the lowest (natural) and the highest (maximum flow control assisted) limits.

REFERENCE

Peterson, C.J., Vukasinovic, B., Glezer, A., Saripalli, K.R., and Packard, N.O., Active Flow Control of Separation in a Branched Duct, AIAA Paper 2016-3771.


Offset Diffuser

model schematics

This investigation focuses on a demonstration of the effectiveness of active flow control approach on suppression of severe flow distortions in offset, aggressive diffusers for advanced propulsion systems. The flow control components are integrated into the diffuser moldline such that they target both the internally-confined flow separation and the secondary flows.

REFERENCE

Burrows, T. J., Gong, Z., Vukasinovic, B., and Glezer, A. Investigation of Trapped Vorticity Concentrations Effected by Hybrid Actuation in an Offset Diffuser, AIAA Paper 2016-0055.


Transonic Shock

model schematics

The feasibility of active flow control approaches in suppression of 'large scale' separated flow unsteadiness resulting from the transonic flow separation over rounded geometry is investigated experimentally. The subsonic upstream flow accelerates over the rounded ramp and terminates at the normal shock that induces the flow separation.

REFERENCES

Gissen, A. N., Vukasinovic, B., Glezer, A., Gogineni, S., Paul, M. C., and Wittich, D. J. Active Transonic Shock Control, AIAA Paper 2014-0942.

Gissen, A. N., Vukasinovic, B., Glezer, A., and Gogineni, S., Active Shock Control in a Transonic Flow, AIAA Paper 2013-3116.

Vukasinovic, B., Gissen, A. N., Glezer, A., and Gogineni, S., Fluidic Control of Transonic Shock-Induced Separation, AIAA Paper 2013-0529.


Dynamic Platform

model schematics

Quasi-steady and transitory controlled interactions of integrated synthetic jet actuators with the cross flow over an axisymmetric bluff body are utilized to induce localized flow attachment over the body's aft end and thereby alter the global aerodynamic forces and moments. The model orientation is varied dynamically by the support traversing mechanism. The objective of active flow control is focused on either suppression or enhancement of asymmetric aerodynamic forces and moments that result from the model's motion, demonstrating capability for flight stabilization and attitude control.

REFERENCES

Lambert, T.J., Vukasinovic, B., and Glezer, A., A Six Degrees of Freedom Dynamic Wire-Driven Traverse, Aerospace 3:11, 2016.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Aerodynamic Flow Control of Wake Dynamics Coupled to a Moving Bluff Body, AIAA Paper 2016-4081.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Coupled Aerodynamic Control of the Turbulent Wake of a Moving Bluff Body, Proc. ETMM11, ERCOFTAC Symposium, 2016.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Aerodynamic Control of Coupled Body-Wake Interactions, AIAA Paper 2016-0053.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Active decoupling of the axisymmetric body wake response to a pitching motion, J. Fluids Struct. 59, pp. 129-145, 2015.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Aerodynamic Flow Control of an Axisymmetric Body in Prescribed Maneuvers, 55th IACAS Conference Proceedings, 2015.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Unsteady Aerodynamic Loads Effected by Flow Control on a Moving Axisymmetric Bluff Body, AIAA Paper 2015-0827.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Aerodynamic Flow Control of a Moving Axisymmetric Bluff Body, AIAA Paper 2014-0932.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Yaw Control of a Moving Axisymmetric Body using Synthetic Jets, AIAA Paper 2013-0106.

Lambert, T.J., Vukasinovic, B., and Glezer, A., Unsteady Aerodynamic Flow Control of a Wire-Suspended, Moving Axisymmetric Body, AIAA Paper 2012-0073.


Turbulent Boundary Layer

streamwise vortex

Manipulation of streamwise vorticity in a turbulent boundary layer is investigated experimentally at high subsonic speeds. Counter-rotating vortex pairs and single-sense vortices are formed and characterized using conventional passive sub-boundary layer micro-ramps and micro-vanes, respectively. Fluidic analogues of these passive devices are established by using surface-mounted synthetic jet actuators. Hybrid manipulation of streamwise vorticity within the boundary layer is demonstrated by simultaneous combination of passive and active actuation which enables robust, controllable ”fail-safe” operation that requires no net mass injection.

REFERENCES

Gissen, A. N., Vukasinovic, B., and Glezer, A., Dynamics of Flow Control in an Emulated Boundary Layer-ingesting Offset Diffuser, Exp. Fluids 55:1794, 2014.

Gissen, A. N., Vukasinovic, B., McMillan, M. L., and Glezer, A., Distortion Management in a Boundary Layer Ingestion Inlet Diffuser Using Hybrid Flow Control, J. Propul. Power 30, pp. 834-844, 2014.

Gissen, A. N., Vukasinovic, B., McMillan, M. L., and Glezer, A., Dynamics of Hybrid Flow Control in a Boundary-Layer-Ingesting Offset Diffuser, AIAA Paper 2011-3096.

Gissen, A. N., Vukasinovic, B., McMillan, M. L., and Glezer, A., Distortion Management in a BLI Inlet Diffuser using Synthetic-Jet Hybrid Flow Control, AIAA Paper 2011-35.

Gissen, A. N., Vukasinovic, B., and Glezer, A., Manipulation of Streamwise Vorticity in an Emulated Diffuser Boundary Layer Using Hybrid Flow Control, AIAA Paper 2010-4586.

Gissen, A. N., Vukasinovic, B., and Glezer, A., Controlled Streamwise Vorticity in Diffuser Boundary Layer using Hybrid Synthetic Jet Actuation, AIAA Paper 2009-4021.


Bluff Body - Turret

model schematics

Flow separation off an airborne bluff-body turret (hemispherical cap elevated on a matching cylinder) can adversely affect optical transmission, and induce excess dynamic loads and structural vibrations. The present work demonstrates the effectiveness of active flow control in mitigation of undesirable effects via flow-separation delay and direct broadband suppression of turbulent motions, particularly those of the energy-bearing, large-scale structures. An alternate approach that leads to ”regularization” of the shedding structures is also explored.

REFERENCES

Vukasinovic, B., Glezer, A., Gordeyev, S., Jumper, E., and Bower, W. W., Flow Control for Aero-Optics Application, Exp. Fluids 50:1492, 2013.

Vukasinovic, B., Glezer, A., Gordeyev, S., Jumper, E., and Bower, W. W., Flow Control for Turret Aero-Optics Applications, AIAA Paper 2013-1014.

Vukasinovic, B., Glezer, A., Gordeyev, S., Jumper, E., and Kibens, V., Hybrid Control of a Turret Wake, AIAA J. 49, pp.1240-1255, 2011.

Vukasinovic, B., Glezer, A., Gordeyev, S., Jumper, E., and Kibens, V., Fluidic Control of a Turret Wake: Aerodynamic and Aero-Optical Effects, AIAA J. 48, pp.1686-1699, 2010.

Vukasinovic, B., Glezer, A., Gordeyev, S., Jumper, E., and Kibens, V., Hybrid Control of a Turret Wake, Part I: Aerodynamic Effects, AIAA Paper 2010-86.

Gordeyev, S., Jumper, E., Vukasinovic, B., Glezer, A., and Kibens, V., Hybrid Control of a Turret Wake, Part II: Aero-Optical Effects, AIAA Paper 2010-438.

Vukasinovic, B., Glezer, A., Gordeyev, S., Jumper, E., and Kibens, V., Fluidic Control of a Turret Wake, Part I: Aerodynamic Effects, AIAA Paper 2009-816.

Gordeyev, S., Jumper, E., Vukasinovic, B., Glezer, A., and Kibens, V., Fluidic Control of a Turret Wake, Part II: Aero-Optical Effects, AIAA Paper 2009-817.

Bower, W. W., Kibens, V., Nahrstedt, D. A., Vukasinovic, B., Glezer, A., Gordeyev, S., Jumper, E., and Saunders, D., Directed Energy Beam Improvement Using Binary Control for the Advanced Tactical Laser (DEBI-BATL), Proc. Beam Control Conference 2009 , April 6-10, 2009, Monterey, CA.

Vukasinovic, B. and Glezer, A., Control of a Separating Flow over a Turret, AIAA Paper 2007-4506.


Axisymmetric Body

model schematics

This investigation focuses on fluidic actuation of the wake behind a wind tunnel model of an axisymmetric bluff body. The aerodynamic forces and moments on the model are altered by induced local attachment and vectoring of the separated base flow. Such segmented alteration of the base flow induces asymmetric aerodynamic forces and moments, which can be used for maneuvering during flight. Both quasi-steady and transitory aerodynamic effects are studied.

REFERENCES

Abramson, P., Vukasinovic, B., and Glezer, A., Fluidic Control of Aerodynamic Forces on a Bluff Body of Revolution, AIAA J. 50, pp.832-843, 2012.

Abramson, P., Vukasinovic, B., and Glezer, A., Direct Measurements of Controlled Aerodynamic Forces on a Wire-suspended Axisymmetric Body, Exp. Fluids 50, pp.1711-1725, 2011.

Abramson, P., Vukasinovic, B., and Glezer, A., Fluidic Control of Steering Aerodynamic Forces on Axisymmetric Bodies using a Mid-Body Cavity, AIAA Paper 2009-4276.

Abramson, P., Culp, J., Vukasinovic, B., and Glezer, A., Fluidic Control of Asymmetric Forces on a Body of Revolution, AIAA Paper 2009-1078.

Abramson, P., Rinehart, C., Vukasinovic, B., and Glezer, A., Fluidic Control of Aerodynamic Forces on a Body of Revolution, AIAA Paper 2007-4505.


Surface-Mounted Hemisphere

model schematics

The flow over a hemisphere presents challenges to separation control beyond those associated with the separation behind two-dimensional aerodynamic surfaces. Locally, the development of a shear layer at the origin of a separated region is subject to the same instability considerations as that in a two-dimensional flow. The three-dimensional geometry of the surface, which curves not only in the streamwise but also in the lateral direction, subjects the developing spanwise vorticity lines to distortion that makes the overall separation region fairly complex. The present work draws on previous experience with the application of high-frequency control to explore the response of the separated region behind a hemisphere to various control strategies, including both pure high-frequency and concomitant low- and high-frequency control.

REFERENCES

Vukasinovic, B., Brzozowski, D., and Glezer, A., Fluidic Control of Separation Over a Hemispherical Turret, AIAA J. 47, pp.2212-2222, 2009.

Vukasinovic, B., Glezer, A., Gordeyev, S., Jumper, E., and Kibens, V., Active Control and Optical Diagnostics of the Flow over a Hemispherical Turret, AIAA Paper 2008-598.

Vukasinovic, B., Brzozowski, D., Glezer, A., Bower, W. W., and Kibens, V., Separation Control over a Surface-Mounted Hemispherical Shell, AIAA Paper 2005-4878.


Planar Shear Layer

schematics The effects of high-frequency fluidic actuation on the evolution of small- and large-scale motions in a turbulent shear layer downstream of a backward-facing step are investigated experimentally. The flow behind the step is characterized in the spatial and spectral domain by high-resolution diagnostic tools. The actuation is applied either as a pure harmonic or amplitude-modulated high-frequency signal, which enhances either direct small-scale motions or both large- and small-scale motions, respectively.

REFERENCES

Vukasinovic, B., Rusak, Z., and Glezer, A., Dissipative Small-scale Actuation of a Turbulent Shear Layer, J. Fluid Mech. 656, pp. 51-81, 2010.

Vukasinovic, B., Glezer, A., and Rusak, Z., Experimental and Numerical Investigation of Controlled, Small-Scale Motions in a Turbulent Shear Layer, Proc. 3rdInternational Symposium on Integrating CFD and Experiments, USAFA, June 20-21, 2007.

Vukasinovic, B. and Glezer, A., Transitory Fluidic Control of Turbulent Shear Flows, AIAA Paper 2006-3227.

Vukasinovic, B., Lucas, D. G., and Glezer, A., Controlled Manipulation of Small- and Large-Scales in a Turbulent Shear Layer, Part I: Experimental Studies, AIAA Paper 2005-4753.

Vukasinovic, B., Lucas, D. G., and Glezer, A., Direct Manipulation of Small-Scale Motions in a Plane Shear Layer, AIAA Paper 2004-2617.


Updated: December 2016