Abstract

A pulsed ruby laser holographic interferometer was used to detect density gradients in the airflow around an airfoil at subsonic speeds in a low speed wind tunnel. These experiments proved that vibration of the optical components or object between exposures of the interferometric hologram does not destroy the detection of density gradients but actually can aid in the flow visualization. The density gradients determined from the fringe pattern analysis are consistent with the anticipated flow pattern.

© 1970 Optical Society of America

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References

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  1. M. H. Horman, Appl. Opt. 4, 333 (1965).
    [CrossRef]
  2. R. L. Powell, K. A. Stetson, J. Opt. Soc. Amer. 55, 1593 (1965).
    [CrossRef]
  3. L. O. Heflinger, R. F. Wuerker, R. E. Brooks, J. Appl. Phys. 37, 642 (1966).
    [CrossRef]
  4. K. A. Haines, B. P. Hildebrand, Appl. Opt. 5, 595 (1966).
    [CrossRef] [PubMed]
  5. J. McDermott, Electronic Design 4, 25 (1969).
  6. L. J. Cutrona, R. D. Buzzard, L. G. Gross, Laser Focus 32 (December1967).
  7. H. H. M. Chau, G. J. Mullaney, Appl. Opt. 6, 981 (1967).
    [CrossRef] [PubMed]
  8. H. W. Liepmann, A. Roshko, Elements of Gas Dynamics (Wiley, New York, 1957), pp. 167–169.
  9. M. Born, E. Wolf, Principles of Optics (Pergamon Press, New York, 1965), pp. 291–300.

1969

J. McDermott, Electronic Design 4, 25 (1969).

1967

L. J. Cutrona, R. D. Buzzard, L. G. Gross, Laser Focus 32 (December1967).

H. H. M. Chau, G. J. Mullaney, Appl. Opt. 6, 981 (1967).
[CrossRef] [PubMed]

1966

K. A. Haines, B. P. Hildebrand, Appl. Opt. 5, 595 (1966).
[CrossRef] [PubMed]

L. O. Heflinger, R. F. Wuerker, R. E. Brooks, J. Appl. Phys. 37, 642 (1966).
[CrossRef]

1965

R. L. Powell, K. A. Stetson, J. Opt. Soc. Amer. 55, 1593 (1965).
[CrossRef]

M. H. Horman, Appl. Opt. 4, 333 (1965).
[CrossRef]

Born, M.

M. Born, E. Wolf, Principles of Optics (Pergamon Press, New York, 1965), pp. 291–300.

Brooks, R. E.

L. O. Heflinger, R. F. Wuerker, R. E. Brooks, J. Appl. Phys. 37, 642 (1966).
[CrossRef]

Buzzard, R. D.

L. J. Cutrona, R. D. Buzzard, L. G. Gross, Laser Focus 32 (December1967).

Chau, H. H. M.

Cutrona, L. J.

L. J. Cutrona, R. D. Buzzard, L. G. Gross, Laser Focus 32 (December1967).

Gross, L. G.

L. J. Cutrona, R. D. Buzzard, L. G. Gross, Laser Focus 32 (December1967).

Haines, K. A.

Heflinger, L. O.

L. O. Heflinger, R. F. Wuerker, R. E. Brooks, J. Appl. Phys. 37, 642 (1966).
[CrossRef]

Hildebrand, B. P.

Horman, M. H.

Liepmann, H. W.

H. W. Liepmann, A. Roshko, Elements of Gas Dynamics (Wiley, New York, 1957), pp. 167–169.

McDermott, J.

J. McDermott, Electronic Design 4, 25 (1969).

Mullaney, G. J.

Powell, R. L.

R. L. Powell, K. A. Stetson, J. Opt. Soc. Amer. 55, 1593 (1965).
[CrossRef]

Roshko, A.

H. W. Liepmann, A. Roshko, Elements of Gas Dynamics (Wiley, New York, 1957), pp. 167–169.

Stetson, K. A.

R. L. Powell, K. A. Stetson, J. Opt. Soc. Amer. 55, 1593 (1965).
[CrossRef]

Wolf, E.

M. Born, E. Wolf, Principles of Optics (Pergamon Press, New York, 1965), pp. 291–300.

Wuerker, R. F.

L. O. Heflinger, R. F. Wuerker, R. E. Brooks, J. Appl. Phys. 37, 642 (1966).
[CrossRef]

Appl. Opt.

Electronic Design

J. McDermott, Electronic Design 4, 25 (1969).

J. Appl. Phys.

L. O. Heflinger, R. F. Wuerker, R. E. Brooks, J. Appl. Phys. 37, 642 (1966).
[CrossRef]

J. Opt. Soc. Amer.

R. L. Powell, K. A. Stetson, J. Opt. Soc. Amer. 55, 1593 (1965).
[CrossRef]

Laser Focus

L. J. Cutrona, R. D. Buzzard, L. G. Gross, Laser Focus 32 (December1967).

Other

H. W. Liepmann, A. Roshko, Elements of Gas Dynamics (Wiley, New York, 1957), pp. 167–169.

M. Born, E. Wolf, Principles of Optics (Pergamon Press, New York, 1965), pp. 291–300.

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Figures (9)

Fig. 1
Fig. 1

Photographed real image of a Freon stream reconstructed from interferometric holograms recorded at (a) 1 60 sec exposure time with a helium–neon laser, and (b) 10−8 sec exposure time with a pulsed ruby laser.

Fig. 2
Fig. 2

A sketch of the final optical system used in the wind tunnel for holographic recording of subsonic flow.

Fig. 3
Fig. 3

Photographed real image of interferometric hologram No. 8 taken with heat introduced in the airstream during the second exposure with the tunnel operating at 10 Q.

Fig. 4
Fig. 4

Photographed real image of interferometric hologram No. D taken with heat introduced in the airstream during the second exposure with the tunnel operating at 2–3 Q.

Fig. 5
Fig. 5

Wake of stalled airfoil.

Fig. 6
Fig. 6

Geometrical arrangement for two point sources separated a distance d apart.

Fig. 7
Fig. 7

Geometrical arrangement when viewing successive light bands in interference pattern.

Fig. 8
Fig. 8

Sketch showing examples of possible vector relationships between actual displacement, d, density gradient, g, and apparent displacement, d.

Fig. 9
Fig. 9

An analysis of the real image of hologram No. 8 resulted in the magnitude and direction of the gradient vectors as shown. The circled numbers at the tail or head of the vectors correspond to the position numbers given in Table II. The remaining numbers correspond to lines of constant density.

Tables (2)

Tables Icon

Table I Interferometric Holograms Recorded in Wind Tunnel

Tables Icon

Table II Measured Value of Δ and Calculated Values of d and g for Hologram No. 8 shown in Fig. 9

Equations (6)

Equations on this page are rendered with MathJax. Learn more.

d sin θ + d sin α = ± m λ ,
sin θ m + 1 sin θ m = ± λ / d .
sin θ m + 1 sin θ m = 2 sin ( 1 2 ) ( θ m + 1 θ m ) cos ( 1 2 ) ( θ m + 1 + θ m ) ψ cos ψ 0
ψ = ± λ / ( d cos ψ 0 ) .
ψ Δ / r .
d = λ r / Δ .

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