Invited: Aerodynamic Flowfield Control Technologies for Highly Integrated Airframe Propulsion Flowpaths

Miller, Daniel; Addington, Gregory

doi:10.2514/6.2004-2625

Cited by 24 publications

(10 citation statements)

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“…Separations and secondary flows result in an increase of total pressure losses in the duct but also in higher flow distortion in the aerodynamic interface plane (AIP) [2,3]. Additionally, separation increases the unsteadiness level.…”

Section: Introductionmentioning

confidence: 99%

Flow Control by Pulsed Jet in a Curved S-Duct: A Spectral Analysis

Garnier

2015

AIAA Journal

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This paper presents an experiment of flow control by supersonic pulsed jets in a very aggressive S-duct typical of modern fighter aircraft engine inlet ducts. The Mach number in the aerodynamic interface plane ranges from 0.2 to 0.4, which is realistic from an application point of view. It was shown that, with continuous blowing, the flow could be fully reattached. The sensitivity of the distortion coefficient to the jet frequency was also clearly evidenced. Surprisingly, it is recommended to avoid actuating the jets at the natural frequencies present in the separated zone of the uncontrolled flow. Besides, it is observed that pulsed jets actuation increases the unsteady flow distortion. Furthermore, in the uncontrolled flow, a lateral movement of the structures associated with high total pressure losses in the aerodynamic interface plane was highlighted. Nomenclature c = velocity of sound, m∕s D 1 = inflow section diameter, mm D 2 = exit section diameter, mm d = jet diameter, mm d a = average duct diameter, mm Ef = spectral density of power, Pa 2 ∕Hz f = frequency, Hz H = offset of the outlet section with respect to the inflow section, mm L = jet stroke length, m L duct = distance from the bell mouth to the translating plug, mm L sep = separation length estimated from the pressure distribution, mm Ma = averaged Mach number in the aerodynamic interface plane Ma 1= isentropic Mach number in the inflow section P dyn = dynamic pressure in the inflow section, Pa Pi = stagnation pressure in the aerodynamic interface plane, Pa Pi 0 = external atmospheric stagnation pressure, Pa Ps 1 = inlet static pressure, Pa Q d = duct mean mass flow rate, g∕s Q dyn = dynamic pressure in the aerodynamic interface plane, Pa Q j = total jet mean mass flow rate, g∕s T = forcing period, s (t, r, n) = frame of reference local to the jets U 1 = velocity in the inflow section, m∕s x, y, z = longitudinal, vertical, and spanwise directions (respectively), mm α = jet pitch angle, deg β = jet skew angle, deg η = duct mean efficiency Φ = angle along the duct circumference, deg <> = operator that denotes an averaging on the 40 pressure sensors in the aerodynamic interface plane

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Section: Introductionmentioning

confidence: 99%

Flow Control by Pulsed Jet in a Curved S-Duct: A Spectral Analysis

Garnier

2015

AIAA Journal

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“…Allan et al, 2006;Brear et al, 2003;Miller et al, 1999Miller et al, , 2004. Allan et al, 2006;Brear et al, 2003;Miller et al, 1999Miller et al, , 2004.…”

Section: Discussionunclassified

Fundamentals and Applications of Modern Flow Control

Joslin¹,

Miller²,

Miller³

2009

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“…(6)(7)(8), (42), (17), and (18), the repeated subscripts i or k represent the coordinates x, y, and z following Einstein summation convention. Equations (17) and (18) are transformed to the generalized coordinate system in computation.…”

Section: A Governing Equationsmentioning

confidence: 99%

“…Both military and commercial aircraft will benefit from the same technology. Flow control is the most promising route to bring significant performance improvement to aircraft [1][2][3][4][5][6][7]. Recently, Zha et al [8][9][10][11] developed a promising airfoil flow control technique using a coflow jet, which significantly increases lift, stall margin, and drag reduction.…”

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confidence: 99%

Numerical Investigations of Injection-Slot-Size Effect on the Performance of Coflow Jet Airfoils

Wang

Haddoukessouni

Levy

et al. 2008

Journal of Aircraft

100

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Three coflow jet airfoils with twice-doubled injection-slot sizes are calculated using a Reynolds-averaged NavierStokes computational fluid dynamics solver with the one-equation Spalart-Allmaras model. At the same angle of attack, the twice-larger injection-slot-size airfoil passes the (about twice-greater) jet mass flow rate, with the momentum coefficients also nearly doubled. The coflow jet airfoil with the largest slot size has the least stall angle of attack. When the injection-slot size is reduced from the maximum by half, the stall angle of attack and the maximum lift coefficient are increased. When the injection-slot size is further reduced by half, the stall angle of attack is still increased, but the maximum lift coefficient is lower due to the smaller momentum coefficient. The trends of the stall angle of attack and maximum lift coefficient agree with the experiment. At low angles of attack, both the computed lift and drag coefficients agree fairly well with the experiment. At high angles of attack, the lift and drag are underpredicted. The reason may be that the Reynolds-averaged Navier-Stokes model cannot handle the turbulence mixing at high angles of attack. Nomenclatureof the field point to the trip location e = total energy per unit mass F = reactionary force J = Jacobian of transformation L = lift l, m, n = normal vectors on , , and surfaces with their magnitudes equal to the elemental surface areas and pointing to the directions of increasing , , and l t , m t , n t = grid moving velocities _ m = mass flow rate Pr = Prandtl number Pr t = turbulent Prandtl number p = pressure q k = total heat flux in Cartesian coordinates R = gas constant Re = Reynolds number R 0 = force from the airfoil surface integral S = magnitude of vorticity in Cartesian coordinates T = temperature t = time U, V, W = contravariant velocities in the , , and directions u, v, w = velocity components in the x, y, and z directions V = velocity vector x, y, z = Cartesian coordinates = angle of attack = ratio of specific heats U = difference of the velocities between the field point and the trip location x t = grid spacing along the wall at the trip location = angle between slot surface and the line normal to the airfoil chord = molecular viscosity t = turbulent viscosity = kinematic viscosity , , = generalized coordinates = density ik = shear stress in Cartesian coordinates ! t = wall vorticity at the wall boundary-layer trip location Subscripts i, j, k = indices L, R = left-and right-hand sides of the interface

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Invited: Aerodynamic Flowfield Control Technologies for Highly Integrated Airframe Propulsion Flowpaths

Cited by 24 publications

References 0 publications

Flow Control by Pulsed Jet in a Curved S-Duct: A Spectral Analysis

Flow Control by Pulsed Jet in a Curved S-Duct: A Spectral Analysis

Fundamentals and Applications of Modern Flow Control

Numerical Investigations of Injection-Slot-Size Effect on the Performance of Coflow Jet Airfoils

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