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  • Arvind Rao & J.P. Buijtenen

    Infrared Signature Modeling of Infrared Signature Modeling of Aircraft Exhaust PlumeAircraft Exhaust Plume

    Faculty of Aerospace Engineering

  • Aircraft Survivability

    It has been observed that linear changes in aircraft survivability produce exponential changes in force effectiveness and aircraft attrition rates. Thus, stealth technology helps aircraft to avoid high aircraft loss rates and complete t h e m i s s i o n o b j e c t i v e s e f f e c t i v e l y

  • Leading Edge

    Aircraft Nose

    Inlet Lip Drop Tank Nose

    Fuselage Nozzle

    Exhaust Plume

    Sun Glint

    Sources of Infrared Signatures

    Radar

  • Exhaust plume, exhaust duct, tail boom heated by exhaust plume and the direct view of hot engine parts like turbine blades. Engine parts at a temperature of 600-700oC.

    Infrared Signatures Sources in a Helicopter

    Tail boom heated by plume

    Engine & Exhaust

  • AIM 4D, AIM 9L/M (Sidewinder), ASRAAM, MICA, Mistral, Python-3, R.530,

    R.550, Shafrir, Stinger

    AA-2, AA-3, AA-5, AA-6, AA- 8, AA-10, AA-11, PL-2, PL-

    5B, PL-7

    Air to Air (AAM)

    Chaparral, Mistral, Redeye, Stinger SA-7, SA-9, SA-13, SA-14, SA-16, SA-18

    Surface to Air (SAM)

    Western MissilesSoviet Block MissileMissile Type

    Common heat-seeking missiles and their origin

    The IR Threat

  • Plume IR Signature Modelling

  • 5km

    0º (Horizon)180º SAM

    90º (Zenith)

    A Simple Mission

    M = 0.8

  • The Modeling Strategy

  • ωd

    ∑ωplDetector element

    Reticle

    MISSILE IR SEEKER

    IR Transparent window R

    SAM

    Plume (discretised)

    aircraft

    SAM IR Seeker (instantaneous field of view )

    [ ] ( ) ( ) ( )min

    1 ,

    1 ,,,,,, )1(

    ξ⋅

    τ⋅ ⎭ ⎬ ⎫

    ⎩ ⎨ ⎧

    −+−+τ−−∑ ∑ = =

    NEI

    AIIAIIAII atm N

    i tptpbgtp

    N

    i fuseifusebgfuseipliplplbgpli

    pl fuse

    RLO =

  • CFD Simulation of the Exhaust Plume

    Nozzle exit plane

    Diamond Shock Expansion fans

    M ac

    h N

    o.

    Magnified view

    Direction of the Plume

    Plume center line

    Plume Mach number contours obtained from CFD

    Nozzle exit plane

    Diamond Shock

    St at

    ic T

    em pe

    ra tu

    re (K

    )

    Magnified view

    Direction of the Plume

    Plume center line

    Plume static temperature contours obtained from CFD

  • Validation of the Exhaust Plume Simulation

    Y/Rnz

    0

    0 .1

    0 .2

    0 .3

    0 .4

    0 .5

    0 .6

    0 .7

    0 .8

    0 .9

    1

    0 0.5 1 1.5 2 2.5 3 3.5 4

    "te mp .txt " "te mp .txt "

    "te mp _h.tx t "

    (T -T

    am b)/

    (T c-T

    am b)

    Present Gauffre

    Heragu etal

    Temperature profile across the jet at X/DN =10

    Y/Rnz

    Concentration profile across the jet at X/DN =10

    0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0.8

    0.9

    1

    0 0.5 1 1.5 2 2.5 3 3.5

    "CO2.txt" "CO2.txt" "CO2.txt"

    C /C

    C

    Present Gauffre

    Heragu etal

  • 0

    50

    100

    150

    200

    250

    300

    350

    400

    450

    500

    3 4 5 6 7 8

    "total.tx t" "total.tx t"

    "heragu1.txt"

    Present Heragu etal. Measured

    Wavelength (µm)

    In te

    ns ity

    (W /m

    2 ⋅S r⋅ µm

    )

    Comparison of predicted infrared intensity (Plume + Nozzle)

    0

    50

    100

    150

    200

    250

    300

    350

    400

    450

    500

    1 2 3 4 5 6 7 8

    "total.txt" "total.txt" "total.txt"

    Plume radiation Nozzle radiation Total radiation

    Wavelength (µm)

    In te

    ns ity

    (W /m

    2 ⋅S r⋅µ

    m )

    predicted infrared intensity (Plume + Nozzle)

    Validation of the Exhaust Plume Simulation

  • Validation of the Exhaust Plume Simulation

    0

    20

    40

    60

    80

    100

    120

    140

    160

    180

    0 2 4 6 8 10 12 14 16 18 20

    "irr_5km.out"

    Wavelength (µm)

    Sp ec

    tra l I

    nt en

    si ty

    (W ⋅m

    -2 ⋅S

    r-1 ⋅µ

    m -1

    )

    H2O

    CO2, CO

    H2O, CO2 CO2

    Spectral radiant intensity of aircraft plume

    Plume emissive bands absorbed by the atmosphere

    0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0.8

    0.9

    1

    0 2 4 6 8 10 12 14 16 18 20

    "temp.txt" "temp.txt"

    N on

    -d im

    en si

    on al

    is ed

    p lu

    m e

    in te

    ns ity

    /A tm

    . t ra

    ns

    Atm. Trans Plume intensity Atm. Trans Plume intensity

  • Exhaust Plume Solver Validation

    Wavelength (µm)

    2 2.5 3.0 3.5 4.0 4.5 5.0 5.5 0

    25

    50

    75

    100

    R el

    at iv

    e S

    pe ct

    ra l I

    nt en

    si ty

    (- )

    La Rocca, A. J., “Artificial Sources,” The Infrared Handbook, 1985

    Spectral intensity from airc`raft plume for Boeing passenger aircraft

    Wavelength (µm)

    0

    5

    10

    15

    20

    25

    30

    35

    40

    45

    2 2.5 3 3.5 4 4.5 5 5.5 6

    "irr_5km.out"

    Plume spectral radiant intensity as transmitted by atmosphere

  • Lock-on Range due to the Plume

    5km

    0º (Horizon)180º SAM

    90º (Zenith)

    Mission

    0 2 4 6

    1

    2

    3

    4

    5

    6

    7

    Wavelength (µm)

    Lo ck

    o n

    R an

    ge (k

    m )

    Lock-on Range due to Plume Radiation

  • • A comprehensive methodology is presented to model the IR signature produced by the aircraft exhaust plume and to evaluate its susceptibility against an IR guided SAM.

    • The results qualitatively match well with the results available in the literature.

    • The prominent band for plume radiation are centered around 2.7 µm, 4.3 µm, 5.5 µm, 6.5 and 15 µm due to the emission by CO2 , CO and H2O present in the plume.

    • Since the exhaust plume and the atmosphere have same radiative participating species, namely H2O, CO2, & CO, most of the IR radiation emitted by the plume is absorbed in the intervening atmosphere.

    • Only the radiation emitted from the broadened wings of the plume emissive bands prominent in the 4.15-4.2 µm band reaches the missile IR detector in the non after burning mode.

    • The aircraft is susceptible to ground based IR guided SAMs due to the radiation emitted by its plume.

    Exhaust Plume Dilution and Mixing for Bell 205 Aircraft

  • Todda Rabba

  • Infrared Signature Suppression

    AIRCRAFT

  • F117-A, Night hawk

    Exhaust pipe of F-117A

    F117 Nozzle Configuration for IR Signature Reduction

  • Schematic of the basic Centre Body Tailpipe used on Bell 205 (UH-1H)

    Bell 205 using Infrared Flares to deceive an incoming IR missile

    Exhaust Plume Dilution and Mixing for Bell 205 Aircraft

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