Abstract

Two new near-resonantly enhanced flow visualization techniques suitable for hypersonic low-density flows in shock or arc tunnels have been developed using seeded lithium (Li) metal as the refractivity-enhancing species. Two semiconductor lasers, single-longitudinal-mode and multimode, are compared with respect to their suitability as light sources for the technique. Transient wake-flow structures around a cylinder and a model of a planetary entry vehicle are visualized to demonstrate the capabilities of this comparatively inexpensive and simple visualization system. The images show flow features which are undetectable with conventional schlieren, shadowgraph, or interferometry techniques. Furthermore, the effect of density inhomogeneities along the line-of-sight outside the region of interest can be reduced by enhancing the refractivity only in selected parts of the flowfield.

© 2008 Optical Society of America

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  1. W. Merzkirch, Flow Visualization, 2nd ed. (Academic, 1987).
  2. G. Settles, Schlieren and Shadowgraph Techniques (Springer-Verlag, 2001).
    [CrossRef]
  3. H. Kleine, “Flow visualization,” in Handbook of Shock Waves, G.Ben-Dor, O. Igra, and T. Elperin, eds. (Academic, 2001), Vol. 1, Chap. 5.1, pp. 683-740.
  4. T. J. McIntyre, H. Kleine, and A. F. P. Houwing, “Optical imaging techniques for hypersonic impulse facilities,” Aeronaut. J. 111, 1-16 (2007).
  5. H. Oertel, Optische Strömungsmesstechnik (G. Braun Karlsruhe, 1989) (in German).
  6. A. Thorne, U. Litzen, and S. Johansson, Spectrophysics: Principles and Applications (Springer-Verlag, 1999).
  7. U.S. National Institute of Standards and Technology, “NIST atomic spectra database,” http://physics.nist.gov/PhysRefData/ASD/index.html.
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    [CrossRef] [PubMed]
  9. D. A. Leonard and J. C. Keck, “Schlieren photography of projectile wakes using resonance radiation,” Tech. Rep. BSD-TDR-62-60 (AVCO Everett, 1962).
  10. D. Bershader, S. G. Prakash, and G. Huhn, “Improved flow visualization by use of resonant refractivity,” AIAA Paper 76-0071 (1976).
  11. A. Rasheed, K. Fujii, H. Hornung, and J. Hall, “Experimental investigation of the flow over a toroidal aerocapture ballute,” AIAA Paper 2001-2460 (2001).
  12. T. McIntyre, A. Bishop, T. Eichmann, and H. Rubinsztein-Dunlop, “Enhanced flow visualization with near-resonant holographic interferometry,” Appl. Opt. 42, 4445-4451 (2003).
    [CrossRef] [PubMed]
  13. A. Bishop, “Spectrally selective holographic interferometry techniques for flow diagnostics,” Ph.D. dissertation (Department of Mechanical Engineering, University of Queensland, Australia, 2001).
  14. A. Bishop, T. McIntyre, B. Littleton, and H. Rubinsztein-Dunlop, “Near-resonant holographic interferometry and absorption measurements of seeded atomic species in a flame,” Appl. Opt. 43, 3391-3400 (2004).
    [CrossRef] [PubMed]
  15. P. Lemieux and H. G. Hornung, “Development and application of streakline visualisation in hypersonic flows,” Exp. Fluids 33, 188-195 (2002).
  16. H.-J. Siebeneck, D. W. Koopman, and J. Cobble, “Resonant optical schlieren system for plasma flow studies,” Rev. Sci. Instrum. 48, 997-1001 (1977).
    [CrossRef]
  17. C. Mundt, R. Boyce, P. Jacobs, and K. Hannemann, “Validation study of numerical simulations by comparison to measurements in piston-driven shock-tunnels,” Aerosp. Sci. Technol. 11, 100-109 (2007).
    [CrossRef]
  18. C. F. Dewey, “Near wake of a blunt body at hypersonic speeds,” AIAA J. 3, 1001-1010 (1965).
    [CrossRef]
  19. L. Brown, School of Aerospace and Mechanical Engineering, University of New South Wales at ADFA, Australia (personal communication, 2007).
  20. R. Hama, “Experimental investigations of wedge base pressure and lip shock,” Tech. Rep. 32-1033 (NASA Jet Propulsion Laboratory, 1966).
  21. R. Larson, C. Scott, D. Elgin, and R. Selver, “Turbulent base flow investigations at Mach number 3,” Tech. Rep. N64-15888 (University of Minnesota, Institute of Technology, Rosemont Aeronautical Laboratories, 1962).
  22. J. F. McCarthy Jr. and T. Kubota, “A study of wakes behind a circular cylinder at M=5.7,” AIAA J. 2, 629-636(1964).
    [CrossRef]
  23. B. Dayman, “Optical free-flight wake studies,” Tech. Rep. 32-364 (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, 1962).
  24. R. Krupinski, “Interference-free model suspension system,” Undergraduate thesis, BE(Aero) (School of Aerospace and Mechanical Engineering, University of New South Wales at ADFA, Australia, 2007).

2007

T. J. McIntyre, H. Kleine, and A. F. P. Houwing, “Optical imaging techniques for hypersonic impulse facilities,” Aeronaut. J. 111, 1-16 (2007).

C. Mundt, R. Boyce, P. Jacobs, and K. Hannemann, “Validation study of numerical simulations by comparison to measurements in piston-driven shock-tunnels,” Aerosp. Sci. Technol. 11, 100-109 (2007).
[CrossRef]

2004

2003

2002

P. Lemieux and H. G. Hornung, “Development and application of streakline visualisation in hypersonic flows,” Exp. Fluids 33, 188-195 (2002).

1977

H.-J. Siebeneck, D. W. Koopman, and J. Cobble, “Resonant optical schlieren system for plasma flow studies,” Rev. Sci. Instrum. 48, 997-1001 (1977).
[CrossRef]

1967

1965

C. F. Dewey, “Near wake of a blunt body at hypersonic speeds,” AIAA J. 3, 1001-1010 (1965).
[CrossRef]

1964

J. F. McCarthy Jr. and T. Kubota, “A study of wakes behind a circular cylinder at M=5.7,” AIAA J. 2, 629-636(1964).
[CrossRef]

Bershader, D.

D. Bershader, S. G. Prakash, and G. Huhn, “Improved flow visualization by use of resonant refractivity,” AIAA Paper 76-0071 (1976).

Bishop, A.

Boyce, R.

C. Mundt, R. Boyce, P. Jacobs, and K. Hannemann, “Validation study of numerical simulations by comparison to measurements in piston-driven shock-tunnels,” Aerosp. Sci. Technol. 11, 100-109 (2007).
[CrossRef]

Brown, L.

L. Brown, School of Aerospace and Mechanical Engineering, University of New South Wales at ADFA, Australia (personal communication, 2007).

Cobble, J.

H.-J. Siebeneck, D. W. Koopman, and J. Cobble, “Resonant optical schlieren system for plasma flow studies,” Rev. Sci. Instrum. 48, 997-1001 (1977).
[CrossRef]

Dayman, B.

B. Dayman, “Optical free-flight wake studies,” Tech. Rep. 32-364 (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, 1962).

Dewey, C. F.

C. F. Dewey, “Near wake of a blunt body at hypersonic speeds,” AIAA J. 3, 1001-1010 (1965).
[CrossRef]

Eichmann, T.

Elgin, D.

R. Larson, C. Scott, D. Elgin, and R. Selver, “Turbulent base flow investigations at Mach number 3,” Tech. Rep. N64-15888 (University of Minnesota, Institute of Technology, Rosemont Aeronautical Laboratories, 1962).

Fujii, K.

A. Rasheed, K. Fujii, H. Hornung, and J. Hall, “Experimental investigation of the flow over a toroidal aerocapture ballute,” AIAA Paper 2001-2460 (2001).

Hall, J.

A. Rasheed, K. Fujii, H. Hornung, and J. Hall, “Experimental investigation of the flow over a toroidal aerocapture ballute,” AIAA Paper 2001-2460 (2001).

Hama, R.

R. Hama, “Experimental investigations of wedge base pressure and lip shock,” Tech. Rep. 32-1033 (NASA Jet Propulsion Laboratory, 1966).

Hannemann, K.

C. Mundt, R. Boyce, P. Jacobs, and K. Hannemann, “Validation study of numerical simulations by comparison to measurements in piston-driven shock-tunnels,” Aerosp. Sci. Technol. 11, 100-109 (2007).
[CrossRef]

Hornung, H.

A. Rasheed, K. Fujii, H. Hornung, and J. Hall, “Experimental investigation of the flow over a toroidal aerocapture ballute,” AIAA Paper 2001-2460 (2001).

Hornung, H. G.

P. Lemieux and H. G. Hornung, “Development and application of streakline visualisation in hypersonic flows,” Exp. Fluids 33, 188-195 (2002).

Houwing, A. F. P.

T. J. McIntyre, H. Kleine, and A. F. P. Houwing, “Optical imaging techniques for hypersonic impulse facilities,” Aeronaut. J. 111, 1-16 (2007).

Huhn, G.

D. Bershader, S. G. Prakash, and G. Huhn, “Improved flow visualization by use of resonant refractivity,” AIAA Paper 76-0071 (1976).

Jacobs, P.

C. Mundt, R. Boyce, P. Jacobs, and K. Hannemann, “Validation study of numerical simulations by comparison to measurements in piston-driven shock-tunnels,” Aerosp. Sci. Technol. 11, 100-109 (2007).
[CrossRef]

Johansson, S.

A. Thorne, U. Litzen, and S. Johansson, Spectrophysics: Principles and Applications (Springer-Verlag, 1999).

Keck, J. C.

D. A. Leonard and J. C. Keck, “Schlieren photography of projectile wakes using resonance radiation,” Tech. Rep. BSD-TDR-62-60 (AVCO Everett, 1962).

Kleine, H.

T. J. McIntyre, H. Kleine, and A. F. P. Houwing, “Optical imaging techniques for hypersonic impulse facilities,” Aeronaut. J. 111, 1-16 (2007).

H. Kleine, “Flow visualization,” in Handbook of Shock Waves, G.Ben-Dor, O. Igra, and T. Elperin, eds. (Academic, 2001), Vol. 1, Chap. 5.1, pp. 683-740.

Koopman, D. W.

H.-J. Siebeneck, D. W. Koopman, and J. Cobble, “Resonant optical schlieren system for plasma flow studies,” Rev. Sci. Instrum. 48, 997-1001 (1977).
[CrossRef]

Krupinski, R.

R. Krupinski, “Interference-free model suspension system,” Undergraduate thesis, BE(Aero) (School of Aerospace and Mechanical Engineering, University of New South Wales at ADFA, Australia, 2007).

Kubota, T.

J. F. McCarthy Jr. and T. Kubota, “A study of wakes behind a circular cylinder at M=5.7,” AIAA J. 2, 629-636(1964).
[CrossRef]

Larson, R.

R. Larson, C. Scott, D. Elgin, and R. Selver, “Turbulent base flow investigations at Mach number 3,” Tech. Rep. N64-15888 (University of Minnesota, Institute of Technology, Rosemont Aeronautical Laboratories, 1962).

Lemieux, P.

P. Lemieux and H. G. Hornung, “Development and application of streakline visualisation in hypersonic flows,” Exp. Fluids 33, 188-195 (2002).

Leonard, D. A.

D. A. Leonard and J. C. Keck, “Schlieren photography of projectile wakes using resonance radiation,” Tech. Rep. BSD-TDR-62-60 (AVCO Everett, 1962).

Littleton, B.

Litzen, U.

A. Thorne, U. Litzen, and S. Johansson, Spectrophysics: Principles and Applications (Springer-Verlag, 1999).

Marlow, W. C.

McCarthy, J. F.

J. F. McCarthy Jr. and T. Kubota, “A study of wakes behind a circular cylinder at M=5.7,” AIAA J. 2, 629-636(1964).
[CrossRef]

McIntyre, T.

McIntyre, T. J.

T. J. McIntyre, H. Kleine, and A. F. P. Houwing, “Optical imaging techniques for hypersonic impulse facilities,” Aeronaut. J. 111, 1-16 (2007).

Merzkirch, W.

W. Merzkirch, Flow Visualization, 2nd ed. (Academic, 1987).

Mundt, C.

C. Mundt, R. Boyce, P. Jacobs, and K. Hannemann, “Validation study of numerical simulations by comparison to measurements in piston-driven shock-tunnels,” Aerosp. Sci. Technol. 11, 100-109 (2007).
[CrossRef]

Oertel, H.

H. Oertel, Optische Strömungsmesstechnik (G. Braun Karlsruhe, 1989) (in German).

Prakash, S. G.

D. Bershader, S. G. Prakash, and G. Huhn, “Improved flow visualization by use of resonant refractivity,” AIAA Paper 76-0071 (1976).

Rasheed, A.

A. Rasheed, K. Fujii, H. Hornung, and J. Hall, “Experimental investigation of the flow over a toroidal aerocapture ballute,” AIAA Paper 2001-2460 (2001).

Rubinsztein-Dunlop, H.

Scott, C.

R. Larson, C. Scott, D. Elgin, and R. Selver, “Turbulent base flow investigations at Mach number 3,” Tech. Rep. N64-15888 (University of Minnesota, Institute of Technology, Rosemont Aeronautical Laboratories, 1962).

Selver, R.

R. Larson, C. Scott, D. Elgin, and R. Selver, “Turbulent base flow investigations at Mach number 3,” Tech. Rep. N64-15888 (University of Minnesota, Institute of Technology, Rosemont Aeronautical Laboratories, 1962).

Settles, G.

G. Settles, Schlieren and Shadowgraph Techniques (Springer-Verlag, 2001).
[CrossRef]

Siebeneck, H.-J.

H.-J. Siebeneck, D. W. Koopman, and J. Cobble, “Resonant optical schlieren system for plasma flow studies,” Rev. Sci. Instrum. 48, 997-1001 (1977).
[CrossRef]

Thorne, A.

A. Thorne, U. Litzen, and S. Johansson, Spectrophysics: Principles and Applications (Springer-Verlag, 1999).

Aeronaut. J.

T. J. McIntyre, H. Kleine, and A. F. P. Houwing, “Optical imaging techniques for hypersonic impulse facilities,” Aeronaut. J. 111, 1-16 (2007).

Aerosp. Sci. Technol.

C. Mundt, R. Boyce, P. Jacobs, and K. Hannemann, “Validation study of numerical simulations by comparison to measurements in piston-driven shock-tunnels,” Aerosp. Sci. Technol. 11, 100-109 (2007).
[CrossRef]

AIAA J.

C. F. Dewey, “Near wake of a blunt body at hypersonic speeds,” AIAA J. 3, 1001-1010 (1965).
[CrossRef]

J. F. McCarthy Jr. and T. Kubota, “A study of wakes behind a circular cylinder at M=5.7,” AIAA J. 2, 629-636(1964).
[CrossRef]

Appl. Opt.

Exp. Fluids

P. Lemieux and H. G. Hornung, “Development and application of streakline visualisation in hypersonic flows,” Exp. Fluids 33, 188-195 (2002).

Rev. Sci. Instrum.

H.-J. Siebeneck, D. W. Koopman, and J. Cobble, “Resonant optical schlieren system for plasma flow studies,” Rev. Sci. Instrum. 48, 997-1001 (1977).
[CrossRef]

Other

W. Merzkirch, Flow Visualization, 2nd ed. (Academic, 1987).

G. Settles, Schlieren and Shadowgraph Techniques (Springer-Verlag, 2001).
[CrossRef]

H. Kleine, “Flow visualization,” in Handbook of Shock Waves, G.Ben-Dor, O. Igra, and T. Elperin, eds. (Academic, 2001), Vol. 1, Chap. 5.1, pp. 683-740.

H. Oertel, Optische Strömungsmesstechnik (G. Braun Karlsruhe, 1989) (in German).

A. Thorne, U. Litzen, and S. Johansson, Spectrophysics: Principles and Applications (Springer-Verlag, 1999).

U.S. National Institute of Standards and Technology, “NIST atomic spectra database,” http://physics.nist.gov/PhysRefData/ASD/index.html.

B. Dayman, “Optical free-flight wake studies,” Tech. Rep. 32-364 (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, 1962).

R. Krupinski, “Interference-free model suspension system,” Undergraduate thesis, BE(Aero) (School of Aerospace and Mechanical Engineering, University of New South Wales at ADFA, Australia, 2007).

D. A. Leonard and J. C. Keck, “Schlieren photography of projectile wakes using resonance radiation,” Tech. Rep. BSD-TDR-62-60 (AVCO Everett, 1962).

D. Bershader, S. G. Prakash, and G. Huhn, “Improved flow visualization by use of resonant refractivity,” AIAA Paper 76-0071 (1976).

A. Rasheed, K. Fujii, H. Hornung, and J. Hall, “Experimental investigation of the flow over a toroidal aerocapture ballute,” AIAA Paper 2001-2460 (2001).

A. Bishop, “Spectrally selective holographic interferometry techniques for flow diagnostics,” Ph.D. dissertation (Department of Mechanical Engineering, University of Queensland, Australia, 2001).

L. Brown, School of Aerospace and Mechanical Engineering, University of New South Wales at ADFA, Australia (personal communication, 2007).

R. Hama, “Experimental investigations of wedge base pressure and lip shock,” Tech. Rep. 32-1033 (NASA Jet Propulsion Laboratory, 1966).

R. Larson, C. Scott, D. Elgin, and R. Selver, “Turbulent base flow investigations at Mach number 3,” Tech. Rep. N64-15888 (University of Minnesota, Institute of Technology, Rosemont Aeronautical Laboratories, 1962).

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Figures (9)

Fig. 1
Fig. 1

Schlieren visualizations of a Mach 10 flow around a planetary entry model in a shock tunnel, taken with a white light source: (a)  f 2 = 3 m ; (b)  f 2 = 10 m .

Fig. 2
Fig. 2

Refractive index and absorption coefficient: Li D 2 ( 670.776 nm ) and D 1 ( 670.791 nm ) transitions. Li mole fraction 0.5%. The dotted curve shows the refractive index in the absence of Doppler broadening.

Fig. 3
Fig. 3

Schematic of the z-type bright-field schlieren setup used in the described tests. The parameter a can be approximated by the pinhole aperture, which is marginally larger than the source image diameter.

Fig. 4
Fig. 4

Schematic of the differential (or shearing) interferometer.

Fig. 5
Fig. 5

Differential interferograms of a Mach 10 flow over a cylinder, condition B; top: visualization with resonant enhancement; bottom: conventional visualization, mirrored image. The model contour has been outlined for clarity.

Fig. 6
Fig. 6

Elements of a hypersonic wake flow, which are characteristic for plane and axisymmetric flows.

Fig. 7
Fig. 7

Different strategies to visualize the inner wake structure at condition B: (a) differential interferometry, high seeding level; (b) Schlieren, high seeding level, 200 pm detuning; (c) Schlieren, low seeding level, 50 pm detuning. The model contours have been outlined for clarity.

Fig. 8
Fig. 8

Mach 10 flow over a cylinder, condition A. Comparison of locally introduced seeding (top) with uniform seeding (bottom, mirrored image). Visualization by differential interferometry. The model contours have been outlined for clarity. Exposure time 0.2 μs .

Fig. 9
Fig. 9

Differential interferometry visualization of an axisymmetric flowfield around a unsuspended model planetary entry vehicle at condition B. Exposure time 0.2 μs .

Tables (1)

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Table 1 Flow Conditions for the T-ADFA Tunnel Experiments

Equations (6)

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I I 0 = f 2 a ξ 1 ξ 2 1 n n y d z
I I 0 = cos 2 ( f 2 θ π λ ξ 1 ξ 2 n y d z ) .
ϵ max = a / f 2 .
n ( ω ) = 1 + q e 2 2 m e ϵ 0 i ( ω 0 i 2 ω 2 ) f i N i ( ω 0 i 2 ω 2 ) 2 + γ i 2 ω 2 ,
α ( ω ) = q e 2 m e ϵ 0 c i ω 2 f i γ i N i ( ω 0 i 2 ω 2 ) 2 + γ i 2 ω 2 .
n D ( ω ) = 1 + m M 2 π k B T ( n ( ω D ) 1 ) e m M v 2 2 k B T d v ,

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