Research Papers

Transient Performance of Separated Flows: Characterization and Active Flow Control

[+] Author and Article Information
J. Saavedra

Mechanical Engineering,
Purdue University,
West Lafayette 47907, IN;
von Karman Institute for Fluid Mechanics,
Rhode-Saint-Genèse B-1640, Belgium
e-mail: jorsaaga@gmail.com

G. Paniagua

Mechanical Engineering,
Purdue University,
West Lafayette 47907, IN;
von Karman Institute for Fluid Mechanics,
Rhode-Saint-Genèse B-1640, Belgium
e-mail: gpaniagua@me.com

Manuscript received June 22, 2018; final manuscript received June 22, 2018; published online September 7, 2018. Editor: Jerzy T. Sawicki.

J. Eng. Gas Turbines Power 141(1), 011002 (Sep 07, 2018) (11 pages) Paper No: GTP-18-1311; doi: 10.1115/1.4040685 History: Received June 22, 2018; Revised June 22, 2018

The aerothermal performance of the low-pressure turbine in unmanned aerial vehicles is significantly abated at high altitude, due to boundary layer separation. Different flow control strategies have been proposed to prevent boundary layer separation, such as dielectric barrier discharges (DBD) and synthetic jets. However, the optimization of the control approach requires a better characterization of the separated regions at transient conditions. The present investigation analyzes the behavior of separated flows, reporting the inception and separation length, allowing the development of efficient flow control methods under nontemporally uniform inlet conditions. The development of separated flows was investigated with numerical simulations including Unsteady Reynolds average Navier–Stokes (URANS) and large Eddy simulations (LES). The present research was performed on a wall-mounted hump, which imposes a pressure gradient representative of the suction side of low pressure turbines. Through sudden flow accelerations, we looked into the dynamic response of the shear layer detachment as it is modulated by the mean flow evolution. Similarly, we studied the behavior of the recirculation bubble under periodic disturbances imposed at various frequencies ranging from 10 to 500 Hz, at which the Reynolds number oscillates between 40,000 and 180,000. As a first step into the flow control, we added a slot to allow flow injection and ingestion upstream of the separation inception. Exploring the behavior of the separated region at different conditions, we defined the envelope for its periodic actuation. We found that by matching the actuator frequency with the frequency response of the separated region, the performance of the actuation is boosted.

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Bons, J. P. , Sondergaard, R. , and Rivir, R. B. , “The Fluid Dynamics of LPT Blade Separation Control Using Pulsed Jets,” ASME Paper No. 2001-GT-0190.
Goldberg, C. , Nalianda, D. , Pilidis, P. , MacManus, D. , and Felder, J. , 2016, “Installed Performance Assessment of a Boundary Layer Ingesting Distributed Propulsion System at Design Point,” AIAA Paper No. AIAA 2016-4800.
Sharma, O. , 1998, “Impact of Reynolds Number on Low Pressure Turbine Performance,” NASA, New York, Report No. CP-1998-206958.
Hura, H. S. , Joseph, J. , and Halstead, D. E. , 2012, “Reynolds Number Effects in a Low Pressure Turbine,” ASME Paper No. GT2012-68501.
Gad-el-Hak, M. , 1996, “Modern Developments in Flow Control,” ASME Appl. Mech. Rev., 49(7), pp. 365–380. [CrossRef]
Byerley, A. R. , Sto¨rmer, O. , Baughn, J. W. , Simon, T. W. , Van Treuren, K. W. , and., and List, J. R. , 2002, “Using Gurney Flaps to Control Laminar Separation on Linear Cascade Blades,” ASME Paper No. GT2002-30662.
Lake, J. , King, P. , and Rivir, R. , 1999, “Reduction of Separation Losses on a Turbine Blade With Low Reynolds Numbers,” 37th Aerospace Sciences Meeting and Exhibit, p. 242.
Volino, R. J. , 2003, “Passive Flow Control on Low-Pressure Turbine Airfoils,” ASME J. Turbomach., 125(4), pp. 754–764. [CrossRef]
Greenblatt, D. , and Wygnanski, I. J. , 2000, “The Control of Flow Separation by Periodic Excitation,” Prog. Aerosp. Sci., 36(7), pp. 487–545. [CrossRef]
Hultgren, L. S. , and Ashpis, D. E. , 2003, “Demonstration of Separation Delay With Glow-Discharge Plasma Actuators,” AIAA Paper No. 2003-1025.
Poggie, J. , 2005, “DC Glow Discharges: A Computational Study for Flow Control Applications,” AIAA Paper No. 2005-5303.
Roy, S. , and Gaitonde, D. V. , 2005, “Multidimensional Collisional Dielectric Barrier Discharge for Flow Separation Control at Atmospheric Pressures,” 35th AIAA Fluid Dynamics Conference and 36th AIAA Plasma Dynamics and Lasers Conference, Toronto, Canada, June 6–9, p. 4631.
Moreau, E. , 2007, “Airflow Control by Non-Thermal Plasma Actuators,” J. Phys. D: Appl. Phys., 40(3), p. 605. [CrossRef]
Huang, J. , Corke, T. C. , and Thomas, F. O. , 2006, “Unsteady Plasma Actuators for Separation Control of Low-Pressure Turbine Blades,” AIAA J., 44(7), pp. 1477–1487. [CrossRef]
Göksel, B. , Greenblatt, D. , Rechenberg, I. , Singh, Y. , Nayeri, C. , and Paschereit, C. , 2006, “Pulsed Plasma Actuators for Separation Flow Control,” Momentum, p. 11.
Porter, C. , McLaughlin, T. , Enloe, C. , Font, G. , Roney, J. , and Baughn, J. , 2007, “Boundary Layer Control Using a DBD Plasma Actuator,” AIAA Paper No. 2007-786.
Post, M. L. , and Corke, T. C. , 2004, “Separation Control on High Angle of Attack Airfoil Using Plasma Actuators,” AIAA J., 42(11), pp. 2177–2184. [CrossRef]
Gaitonde, D. V. , Visbal, M. R. , and Roy, S. , 2005, “Control of Flow past a Wing Section With Plasma-Based Body Forces,” AIAA Paper No. 2005-5302.
Rethmel, C. , Little, J. , Takashima, K. , Sinha, A. , Adamovich, I. , and Samimy, M. , 2011, “Flow Separation Control Over an Airfoil With Nanosecond Pulse Driven DBD Plasma Actuators,” AIAA Paper No. 2011-487.
Volino, R. J. , 2003, “Separation Control on Low-Pressure Turbine Airfoils Using Synthetic Vortex Generator Jets,” ASME J. Turbomach., 125(4), pp. 765–777. [CrossRef]
Sondergaard, R. , Rivir, R. B. , and Bons, J. P. , 2002, “Control of Low-Pressure Turbine Separation Using Vortex-Generator Jets,” J. Propulsion Power, 18(4), pp. 889–895. [CrossRef]
Schobeiri, M. T. , Öztürk, B. , and Ashpis, D. E. , 2005, “On the Physics of Flow Separation along a Low Pressure Turbine Blade Under Unsteady Flow Conditions,” ASME J. Fluids Eng., 127(3), pp. 503–513. [CrossRef]
Wissink, J. , 2003, “DNS of Separating, Low Reynolds Number Flow in a Turbine Cascade With Incoming Wakes,” Int. J. Heat Fluid Flow, 24(4), pp. 626–635. [CrossRef]
Seifert, A. , and Pack, L. G. , 2002, “Active Flow Separation Control on Wall-Mounted Hump at High Reynolds Numbers,” AIAA J., 40(7), pp. 1363–1372. [CrossRef]
He, C. , Corke, T. C. , and Patel, M. P. , 2007, “Numerical and Experimental Analysis of Plasma Flow Control Over a Hump Model,” AIAA Paper No. 2007-935.
Pescini, E. , Marra, F. , De Giorgi, M. , Francioso, L. , and Ficarella, A. , 2017, “Investigation of the Boundary Layer Characteristics for Assessing the DBD Plasma Actuator Control of the Separated Flow at Low Reynolds Numbers,” Exp. Therm. Fluid Sci., 81, pp. 482–498. [CrossRef]
Martínez, D. , Pescini, E. , Marra, F. , De Giorgi, M. , and Ficarella, A. , “Analysis of the Performance of Plasma Actuators Under Low-Pressure Turbine Conditions Based on Experiments and URANS Simulations,” ASME Paper No. GT2017-64867.
Celik, I. B. , Ghia, U. , and Roache, P. J. , 2008, “Procedure for Estimation and Reporting of Uncertainty Due to Discretization in {CFD} Applications,” ASME J. Fluids Eng., 130(7), p. 078001. [CrossRef]
Menter, F. R. , 1994, “Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications,” AIAA J., 32(8), pp. 1598–1605. [CrossRef]
Menter, F. , Langtry, R. , and Völker, S. , 2006, “Transition Modelling for General Purpose CFD Codes,” Flow, Turbul. Combust., 77(1-4), pp. 277–303. [CrossRef]
Clark, J. , and Grover, E. , 2007, “Assessing Convergence in Predictions of Periodic-Unsteady Flowfields,” ASME J. Turbomach., 129(4), pp. 740–749. [CrossRef]
Vogel, J. , and Eaton, J. , 1985, “Combined Heat Transfer and Fluid Dynamic Measurements Downstream of a Backward-Facing Step,” ASME J. Heat Transfer, 107(4), pp. 922–929. [CrossRef]
Germano, M. , Piomelli, U. , Moin, P. , and Cabot, W. H. , 1991, “A Dynamic Subgrid‐Scale Eddy Viscosity Model,” Phys. Fluids A: Fluid Dyn. (1989-1993), 3(7), pp. 1760–1765. [CrossRef]
Lilly, D. K. , 1992, “A Proposed Modification of the Germano Subgrid‐Scale Closure Method,” Phys. Fluids A: Fluid Dyn. (1989-1993), 4(3), p. 633. [CrossRef]
Choi, H. , and Moin, P. , 2012, “Grid-Point Requirements for Large Eddy Simulation: Chapman's Estimates Revisited,” Phys. Fluids, 24(1), p. 011702. [CrossRef]
Chapman, D. R. , 1979, “Computational Aerodynamics Development and Outlook,” AIAA J., 17(12), pp. 1293–1313. [CrossRef]
Launder, B. E. , and Jones, W. P. , 1968, On the Prediction of Laminarisation, ARC Heat and Mass Transfer Subcommittee Meeting, Apr. 5.
Spalart, P. R. , 1986, “Numerical Simulation of Boundary Layers—Part 3: Turbulence and Relaminarization in Sink Flows,” National Aeronautics and Space Administration, Washington, DC, Report No. NASA-TM-88220. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880004901.pdf
Biswas, G. , Breuer, M. , and Durst, F. , 2004, “Backward-Facing Step Flows for Various Expansion Ratios at Low and Moderate Reynolds Numbers,” ASME J. Fluids Eng., 126(3), pp. 362–374. [CrossRef]
Huang, J. , Corke, T. C. , and Thomas, F. O. , 2006, “Plasma Actuators for Separation Control of Low-Pressure Turbine Blades,” AIAA J., 44(7), pp. 51–57. [CrossRef]


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Fig. 1

Domain generation for flow separation dynamic scales analysis: (a) geometry, (b) slope of the wall mounted hump, and (c) curvature of the wall mounted hump evolution

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Fig. 2

Two-dimensional domain for numerical analysis of flow separation dynamics

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Fig. 3

Mesh sensitivity analysis: (a) grid convergence index, (b) momentum boundary layer profiles at various axial locations: 0.15, 0.3, and 0.45 m, and (c) wall shear stress evolution along the plate

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Fig. 4

Validation of the numerical methodology

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Fig. 5

LES numerical domain

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Fig. 6

(a) inlet boundary condition for sudden flow acceleration, (b) inlet boundary condition for periodic flow perturbation, (c) massflow through the domain, and (d) drag coefficient during the sudden flow acceleration

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Fig. 7

Free stream, wall fluxes and separated region evolution during the sudden flow acceleration

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Fig. 8

Axial velocity contours at various instances during the blowdown compared to steady evaluations along the profile

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Fig. 9

Mean flow, separated region and wall fluxes evolution at various excitation frequencies for complete inlet fluctuation period

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Fig. 10

Axial velocity profiles at various instances during the period at x = 0.25 m

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Fig. 11

Integral drag along the plate for various excitation frequencies: (a) drag signal after periodic convergence and (b) fast Fourier transform of the drag signal for 8 periods

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Fig. 12

(a) Energy spectra on the domain at three given points and (b) axial velocity contour at t/p = 0.75 with q-criterion display

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Fig. 13:

Large Eddy simulation versus 2D SST transitional results: (a) bubble length, (b) separation inception, and (c) heat transfer coefficient at x = 0.25 m during the periodic oscillation

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Fig. 14

Domain for injection analysis

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Fig. 15

Flow separation control through slot pressure

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Fig. 16

Slot pressure fluctuation effect on the separated flow region

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Fig. 17

Momentum profiles at x = 0.25 m for various injection frequencies

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Fig. 18

Thermal boundary layer profiles at x = 0.25 m for various injection frequencies

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Fig. 19

Injection pressure amplitude effect on the separated flow region and thermal isolation

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Fig. 20

Injection pressure amplitude effect on the separated flow region and thermal insulation



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