Effects of passive porous walls on boundary-layer instability

Carpenter, Peter W.; Porter, Lee J.

doi:10.2514/3.14775

Cited by 7 publications

(13 citation statements)

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“…This mode may be stabilized by wall cooling, suction and favourable pressure gradient. Another way to damp the first mode is by a very thin perforated sheet stretched over a plenum chamber (Carpenter & Porter 2001). When the TS waves propagate along the boundary layer, the fluctuating pressure forces air in and out of the plenum chamber that modifies the wall boundary conditions for the disturbances.…”

Section: Introductionmentioning

confidence: 99%

Stabilization of a hypersonic boundary layer using an ultrasonically absorptive coating

et al. 2003

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Experimental and theoretical studies of the effect of an ultrasonically absorptive coating (UAC) on hypersonic boundary-layer stability are described. A thin coating of fibrous absorbent material (felt metal) was selected as a prototype of a practical UAC. Experiments were performed in the Mach 6 wind tunnel on a $7^{\circ}$ half-angle sharp cone whose longitudinal half-surface was solid and other half-surface was covered by a porous coating. Hot-wire measurements of ‘natural’ disturbances and artificially excited wave packets were conducted on both solid and porous surfaces. Stability analysis of the UAC effect on two- and three-dimensional disturbances showed that the porous coating strongly stabilizes the second mode and marginally destabilizes the first mode. These results are in qualitative agreement with the experimental data for natural disturbances. The theoretical predictions are in good quantitative agreement with the stability measurements for artificially excited wave packets associated with the second mode. Stability calculations for the cooled wall case showed the feasibility of achieving a dramatic increase of the laminar run using a thin porous coating of random microstructure.

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Section: Introductionmentioning

confidence: 99%

Stabilization of a hypersonic boundary layer using an ultrasonically absorptive coating

et al. 2003

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“…1 of the boundary-layer displacement thickness) can dramatically reduce the second-mode growth rate. In contrast to the TS waves (Carpenter & Porter 2001), the second mode is effectively suppressed without a plenum chamber underneath the porous sheet. This significantly simplifies practical application.…”

Section: Introductionmentioning

confidence: 89%

“…When the TS waves propagate along the boundary layer, the fluctuating pressure forces air in and out of the plenum chamber that modifies the wall boundary conditions for the disturbances. Carpenter & Porter (2001) conducted a stability analysis for the incompressible boundary layer on a flat plate and showed that the TS waves are stabilized when the wall admittance phase is close to in. Their analysis is based on linear stability theory for the boundary layer with modified boundary conditions on the perforated wall.…”

Section: Introductionmentioning

confidence: 99%

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Mathematical Fluid Dynamics of Store and Stage Separation

Malmuth¹,

Шалаев²,

Федоров³

2005

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“…The ensuing interaction of the ejection or suction with the cross flow can result in a local modification of the pressure distribution (and pressure gradients), lead to alteration of the flow over the surface, and in some cases result in global changes in aerodynamic forces. Several examples include reduction of the drag of bluff bodies by base bleed (Tanner, 1975), laminar flow control (Carpenter and Porter, 2001), tip vortex control (Han and Leishman, 2004), aerodynamic maneuvering forces (Hunter, Viken, Wood, and Bauer, 2001), mitigation of flow separation (Lopera, Ng, and Patel, 2004), and reduction of shock-induced separation on transonic airfoils (Savu and Trifu, 1984). It is noteworthy that studies of multiple slots that act as conduits for bleed flow between the pressure and suction side of various airfoils were investigated as early as the 1920s (Lachmann, 1924, andWeick andShortal, 1932).…”

Section: Overviewmentioning

confidence: 99%

Aero-Effected Flight Control Using Distributed Active Bleed

Glezer¹,

Leonard²

2012

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The public reporting burden for this collection l:>f inforTTilltion is estimab:d to avefllge 1 hour per response, including the time for reviewing instructions, seen::hing existing data soun::es, gllllhering and maintaining the data needed, and completing and reviewing tha collection l:>f Information. Send ocmmenla regarding this burden estimate or any other aspectl:>f this collection l:>f Information, Including suggestions for reducing the burden, to the Department l:>f Defense, Exeoutive Servioe Directorab: (07() SPONSOR/MONITOR'S REPORTArlington, VA 22203 NUMBER(S)AFRL-OSR-VA-TR-2012-0276 DISTRIBUTION/AVAILABILITY STATEMENT Unlimited SUPPLEMENTARY NOTES14. ABSTRACT Aero-ettected flight control us1ng dlstnbuted act1ve bleed dnven by pressure dltterences on 11tt1ng surfaces and regulated by low-power louver actuators was investigated experimentally and theoretically. The flow mechanisms of the interaction between unsteady bleed and the cross flows were investigated on a 2-D static and dynamically pitching Clark-Y model integrated with piezoelectric louvers. The effects of leading and trailing edge bleed on the aerodynamic forces and the flow field were measured using load cells and PIV. Trailing edge bleed at low AoA effects nearly-linear variation of the pitching moment (±12%) with minimal drag penalty. Leading edge bleed at high AoA leads to large variations in lift and pitching moment, and extends the stall margin enabling up to 50% variation in the baseline lift without external control surfaces. Numerical simulations using immersed boundary and penalty methods, showed that the bleed near the trailing edge induced changes in circulation to maintain the Kutta condition. This change in circulation accounts for 5!7 of the total change in lift with center-of-pressure at c/4, in accordance with classical theory. A vortex-based reduced order model was developed to predict aerodynamic forces on an arbitrarily pitching and plunging airfoil with unsteady bleed. Bleed actuation was also investigated on a pitching airfoil over a wide range of AoA. At high reduced frequencies (k > 0.1 ), the bleed alters the dynamics of vorticity production and advection and interacts with the dynamic stall vortex to increase the stability of the pitch motion and minimize negative damping with low lift penalty. SUBJECT TERMS AbstractA novel, scalable approach to aero-effected flight control of lifting surfaces using distributed active bleed was investigated experimentally and theoretically. Aerodynamic control is achieved by large-area surface bleed of air that is driven by the pressure differences in flight and is regulated by low-power surface-integrated louver actuators. The joint numerical-experimental investigation focused on the flow mechanisms of the interaction between the bleed and the cross flow and aerodynamic effects of unsteady bleed on a 2-D wing model. Particular emphasis was placed on the generation and regulation of vorticity concentrations that alter the wing's apparent aerodynamic shape and thereby its aerodynamic ...

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Effects of passive porous walls on boundary-layer instability

Cited by 7 publications

References 0 publications

Stabilization of a hypersonic boundary layer using an ultrasonically absorptive coating

Stabilization of a hypersonic boundary layer using an ultrasonically absorptive coating

Mathematical Fluid Dynamics of Store and Stage Separation

Aero-Effected Flight Control Using Distributed Active Bleed

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