Abstract

With a first application of semiconductor lasers to absorption measurements of seeded atomic Rb in high-enthalpy flow fields, a diagnostic technique for time-resolved determination of flow velocity and gas temperature with a line-shape analysis was developed. In our measurements a GaAlAs diode laser was used to scan repetitively at 15 kHz over 1.3 cm-1 across the D2 resonance transition (5S 1/2 → 5P 3/2, 780.2 nm) of seeded atomic Rb to obtain multiple absorption line shapes. The time-dependent signal contains highly resolved spectral line-shape information, which we interpret by fitting the spectrally resolved line shapes to Voigt profiles. Kinetic temperatures in the range 900–1400 K and gas velocities in the range 3900–6200 ms-1 were obtained from the Doppler-broadened component of the line shape and from the Doppler shift, respectively, of the absorption frequency.

© 1998 Optical Society of America

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  1. W. H. Beck, G. Eitelberg, D. Vennemann, “HEG–a new shock tunnel for high enthalpies,” presented at the European Forum on Wind Tunnels, University of Southampton, Southampton, UK, 14–17 September 1992.
  2. K. Hannemann, “Numerical simulation of chemically reacting hypersonic flows related to the HEG,” Internal Rep. 221-92 A16 [Institute for Fluid Mechanics, German Aerospace Research Establishment (DLR) (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1992].
  3. R. M. Krek, G. Eitelberg, “Classical characterisation of HEG,” Internal Rep. 223-94 A 50 [Institute for Fluid Mechanics, German Aerospace Research Establishment (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1994].
  4. W. H. Beck, C. Dankert, G. Eitelberg, G. Gundlach. “Preliminary laserinduced fluorescence measurements in several facilities in preparation for application to studies in the High Enthalpy Shock Tunnel Göttingen (HEG), paper AIAA-92-0143, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).
  5. D. Kastell, M. Carl, G. Eitelberg, “Phase step holographic interferometry applied to hypervelocity, non-equilibrium cylinder flow,” Exp. Fluids 22, 57–66 (1997).
    [CrossRef]
  6. B. Rosier, A. K. Mohamed, D. Henry, S. Juville, “Measures par spectroscopie d’absorption diode laser à la soufflerie F4,” Internal Rep. 8/4383 PY (Direction de la Physique Generale, Office National d’Etudes et de Recherches Aerospatiales, Chatillon, France, 1993).
  7. H. A. Chang, D. S. Baer, R. K. Hanson, “Semiconductor laser diagnostics of atomic oxygen for hypersonic flowfield measurements,” paper AIAA-92-0628, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).
  8. O. Trinks, “Diodenlaser-Absorptionsspektroskopie am atomaren Rubidium im Hochenthalpiekanal HEG zur Bestimmung der Strömungsgeschwindigkeit und Gastemperatur,” Internal Rep. 223-97 A31 [Institute for Fluid Mechanics, German Aerospace Center (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1997].
  9. J. B. Taylor, I. Langmuir, Phys. Rev. 51, 753 (1936).
    [CrossRef]
  10. F. Wittgrefe, “Light-induced drift of rubidium and spectral properties of semiconductor lasers,” Ph.D. dissertation (University of Leiden, Leiden, The Netherlands, 1996).
  11. I. M. Vardavas, “Modelling reactive gas flows within shock tunnels,” Aust. J. Chem. 37, 157–177 (1984).
  12. M. K. McIntosh, “Computer program for the numerical calculation of frozen and equilibrium conditions in shock tunnels,” Internal Rep. (Department of Physics, Australian National University, Canberra, Australia, 1968).
  13. W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

1997 (1)

D. Kastell, M. Carl, G. Eitelberg, “Phase step holographic interferometry applied to hypervelocity, non-equilibrium cylinder flow,” Exp. Fluids 22, 57–66 (1997).
[CrossRef]

1984 (1)

I. M. Vardavas, “Modelling reactive gas flows within shock tunnels,” Aust. J. Chem. 37, 157–177 (1984).

1936 (1)

J. B. Taylor, I. Langmuir, Phys. Rev. 51, 753 (1936).
[CrossRef]

Andresen, P.

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

Baer, D. S.

H. A. Chang, D. S. Baer, R. K. Hanson, “Semiconductor laser diagnostics of atomic oxygen for hypersonic flowfield measurements,” paper AIAA-92-0628, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

Beck, W. H.

W. H. Beck, C. Dankert, G. Eitelberg, G. Gundlach. “Preliminary laserinduced fluorescence measurements in several facilities in preparation for application to studies in the High Enthalpy Shock Tunnel Göttingen (HEG), paper AIAA-92-0143, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

W. H. Beck, G. Eitelberg, D. Vennemann, “HEG–a new shock tunnel for high enthalpies,” presented at the European Forum on Wind Tunnels, University of Southampton, Southampton, UK, 14–17 September 1992.

Bito, H.

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

Carl, M.

D. Kastell, M. Carl, G. Eitelberg, “Phase step holographic interferometry applied to hypervelocity, non-equilibrium cylinder flow,” Exp. Fluids 22, 57–66 (1997).
[CrossRef]

Chang, H. A.

H. A. Chang, D. S. Baer, R. K. Hanson, “Semiconductor laser diagnostics of atomic oxygen for hypersonic flowfield measurements,” paper AIAA-92-0628, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

Dankert, C.

W. H. Beck, C. Dankert, G. Eitelberg, G. Gundlach. “Preliminary laserinduced fluorescence measurements in several facilities in preparation for application to studies in the High Enthalpy Shock Tunnel Göttingen (HEG), paper AIAA-92-0143, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

Eitelberg, G.

D. Kastell, M. Carl, G. Eitelberg, “Phase step holographic interferometry applied to hypervelocity, non-equilibrium cylinder flow,” Exp. Fluids 22, 57–66 (1997).
[CrossRef]

W. H. Beck, G. Eitelberg, D. Vennemann, “HEG–a new shock tunnel for high enthalpies,” presented at the European Forum on Wind Tunnels, University of Southampton, Southampton, UK, 14–17 September 1992.

W. H. Beck, C. Dankert, G. Eitelberg, G. Gundlach. “Preliminary laserinduced fluorescence measurements in several facilities in preparation for application to studies in the High Enthalpy Shock Tunnel Göttingen (HEG), paper AIAA-92-0143, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

R. M. Krek, G. Eitelberg, “Classical characterisation of HEG,” Internal Rep. 223-94 A 50 [Institute for Fluid Mechanics, German Aerospace Research Establishment (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1994].

Gundlach, G.

W. H. Beck, C. Dankert, G. Eitelberg, G. Gundlach. “Preliminary laserinduced fluorescence measurements in several facilities in preparation for application to studies in the High Enthalpy Shock Tunnel Göttingen (HEG), paper AIAA-92-0143, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

Hannemann, K.

K. Hannemann, “Numerical simulation of chemically reacting hypersonic flows related to the HEG,” Internal Rep. 221-92 A16 [Institute for Fluid Mechanics, German Aerospace Research Establishment (DLR) (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1992].

Hanson, R. K.

H. A. Chang, D. S. Baer, R. K. Hanson, “Semiconductor laser diagnostics of atomic oxygen for hypersonic flowfield measurements,” paper AIAA-92-0628, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

Henry, D.

B. Rosier, A. K. Mohamed, D. Henry, S. Juville, “Measures par spectroscopie d’absorption diode laser à la soufflerie F4,” Internal Rep. 8/4383 PY (Direction de la Physique Generale, Office National d’Etudes et de Recherches Aerospatiales, Chatillon, France, 1993).

Juville, S.

B. Rosier, A. K. Mohamed, D. Henry, S. Juville, “Measures par spectroscopie d’absorption diode laser à la soufflerie F4,” Internal Rep. 8/4383 PY (Direction de la Physique Generale, Office National d’Etudes et de Recherches Aerospatiales, Chatillon, France, 1993).

Kastell, D.

D. Kastell, M. Carl, G. Eitelberg, “Phase step holographic interferometry applied to hypervelocity, non-equilibrium cylinder flow,” Exp. Fluids 22, 57–66 (1997).
[CrossRef]

Kishimoto, T.

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

Krek, R. M.

R. M. Krek, G. Eitelberg, “Classical characterisation of HEG,” Internal Rep. 223-94 A 50 [Institute for Fluid Mechanics, German Aerospace Research Establishment (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1994].

Langmuir, I.

J. B. Taylor, I. Langmuir, Phys. Rev. 51, 753 (1936).
[CrossRef]

McIntosh, M. K.

M. K. McIntosh, “Computer program for the numerical calculation of frozen and equilibrium conditions in shock tunnels,” Internal Rep. (Department of Physics, Australian National University, Canberra, Australia, 1968).

Mohamed, A.

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

Mohamed, A. K.

B. Rosier, A. K. Mohamed, D. Henry, S. Juville, “Measures par spectroscopie d’absorption diode laser à la soufflerie F4,” Internal Rep. 8/4383 PY (Direction de la Physique Generale, Office National d’Etudes et de Recherches Aerospatiales, Chatillon, France, 1993).

Niederbäumer, C.

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

Rosier, B.

B. Rosier, A. K. Mohamed, D. Henry, S. Juville, “Measures par spectroscopie d’absorption diode laser à la soufflerie F4,” Internal Rep. 8/4383 PY (Direction de la Physique Generale, Office National d’Etudes et de Recherches Aerospatiales, Chatillon, France, 1993).

Taylor, J. B.

J. B. Taylor, I. Langmuir, Phys. Rev. 51, 753 (1936).
[CrossRef]

Trinks, O.

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

O. Trinks, “Diodenlaser-Absorptionsspektroskopie am atomaren Rubidium im Hochenthalpiekanal HEG zur Bestimmung der Strömungsgeschwindigkeit und Gastemperatur,” Internal Rep. 223-97 A31 [Institute for Fluid Mechanics, German Aerospace Center (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1997].

Vardavas, I. M.

I. M. Vardavas, “Modelling reactive gas flows within shock tunnels,” Aust. J. Chem. 37, 157–177 (1984).

Vennemann, D.

W. H. Beck, G. Eitelberg, D. Vennemann, “HEG–a new shock tunnel for high enthalpies,” presented at the European Forum on Wind Tunnels, University of Southampton, Southampton, UK, 14–17 September 1992.

Wittgrefe, F.

F. Wittgrefe, “Light-induced drift of rubidium and spectral properties of semiconductor lasers,” Ph.D. dissertation (University of Leiden, Leiden, The Netherlands, 1996).

Wollenhaupt, M.

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

Aust. J. Chem. (1)

I. M. Vardavas, “Modelling reactive gas flows within shock tunnels,” Aust. J. Chem. 37, 157–177 (1984).

Exp. Fluids (1)

D. Kastell, M. Carl, G. Eitelberg, “Phase step holographic interferometry applied to hypervelocity, non-equilibrium cylinder flow,” Exp. Fluids 22, 57–66 (1997).
[CrossRef]

Phys. Rev. (1)

J. B. Taylor, I. Langmuir, Phys. Rev. 51, 753 (1936).
[CrossRef]

Other (10)

F. Wittgrefe, “Light-induced drift of rubidium and spectral properties of semiconductor lasers,” Ph.D. dissertation (University of Leiden, Leiden, The Netherlands, 1996).

M. K. McIntosh, “Computer program for the numerical calculation of frozen and equilibrium conditions in shock tunnels,” Internal Rep. (Department of Physics, Australian National University, Canberra, Australia, 1968).

W. H. Beck, O. Trinks, M. Wollenhaupt, A. Mohamed, C. Niederbäumer, P. Andresen, T. Kishimoto, H. Bito, “Probing of the reservoir, free stream and shock layers in HEG using spectroscopic techniques,” presented at the Twenty-First International Symposium on Shock Waves, Great Keppel Island, Australia, 20–25 July 1997.

B. Rosier, A. K. Mohamed, D. Henry, S. Juville, “Measures par spectroscopie d’absorption diode laser à la soufflerie F4,” Internal Rep. 8/4383 PY (Direction de la Physique Generale, Office National d’Etudes et de Recherches Aerospatiales, Chatillon, France, 1993).

H. A. Chang, D. S. Baer, R. K. Hanson, “Semiconductor laser diagnostics of atomic oxygen for hypersonic flowfield measurements,” paper AIAA-92-0628, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

O. Trinks, “Diodenlaser-Absorptionsspektroskopie am atomaren Rubidium im Hochenthalpiekanal HEG zur Bestimmung der Strömungsgeschwindigkeit und Gastemperatur,” Internal Rep. 223-97 A31 [Institute for Fluid Mechanics, German Aerospace Center (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1997].

W. H. Beck, G. Eitelberg, D. Vennemann, “HEG–a new shock tunnel for high enthalpies,” presented at the European Forum on Wind Tunnels, University of Southampton, Southampton, UK, 14–17 September 1992.

K. Hannemann, “Numerical simulation of chemically reacting hypersonic flows related to the HEG,” Internal Rep. 221-92 A16 [Institute for Fluid Mechanics, German Aerospace Research Establishment (DLR) (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1992].

R. M. Krek, G. Eitelberg, “Classical characterisation of HEG,” Internal Rep. 223-94 A 50 [Institute for Fluid Mechanics, German Aerospace Research Establishment (Deutsche Forschungsanstalt für Luft und Raumfahrt), Göttingen, Germany, 1994].

W. H. Beck, C. Dankert, G. Eitelberg, G. Gundlach. “Preliminary laserinduced fluorescence measurements in several facilities in preparation for application to studies in the High Enthalpy Shock Tunnel Göttingen (HEG), paper AIAA-92-0143, presented at the Thirtieth Aerospace Sciences Meeting and Exhibit, Reno, Nev., 6–9 January 1992 (American Institute of Aeronautics and Astronautics, New York, 1992).

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Figures (6)

Fig. 1
Fig. 1

Experimental setup for diode-laser absorption measurement at HEG with Rb. The lower schematic shows a detailed picture of the test chamber with both laser beam directions, the light-guiding pipes, and the rake position.

Fig. 2
Fig. 2

Raw signal of Pitot pressure, extinction measurement, and the transmission measurements observed with the orthogonal (90°) and the 53° diode-laser beam during a HEG run (condition I). Additional details of the transmission signals are shown in the inset.

Fig. 3
Fig. 3

Rb has two isotopes (72% 85Rb and 28% 87Rb); both show a doublet splitting of their ground state, which is due to the hyperfine interaction. This doublet splitting is quite large compared with the Doppler width (0.1007 cm-1 for 85Rb and 0.2262 cm-1 for 87Rb).

Fig. 4
Fig. 4

Example of interpreting the absorption signal by fitting a model of the line-broadening and shifting mechanisms to obtain a kinetic temperature of the Doppler component of the line shape and gas velocity from the Doppler shift of the absorption frequency.

Fig. 5
Fig. 5

Sensitivity of temperature and velocity measurements obtained with the absorption technique. Comparison between the best simulated fit and simulated spectra, with a parameter value offset by 20% for temperature and 5% for velocity (left-hand plots). The residual plot (Ψ2) is the squared difference between the best fit and simulated absorption features with floating parameter value offsets.

Fig. 6
Fig. 6

Time development of Pitot pressure, temperature, and flow velocity, as determined from diode-laser absorption measurements with Rb at HEG condition I; t = 0 corresponds to the moment of shock initiation. Each of the two data traces belongs to measurements performed with and without the presence of a measurement rake in the test section.

Tables (3)

Tables Icon

Table 1 Calculated Conditions for the Free-Stream Gas Flows Produced in the HEG Facilitya

Tables Icon

Table 2 Temperature and Flow Velocity, as Determined from Diode-laser-absorption Measurement with Two Speciesa

Tables Icon

Table 3 Summary of Measured Kinetic Temperature (TRb) and Flow Velocity (uRb) for Different Flow Conditions with the Rake in the Free-Stream Flow and Determined from Absorption Lines by Means of the D2 Resonance Transition of Rba

Equations (1)

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Δ ν ¯ D cm - 1 = 2 2 R   ln   2 1 / 2 c   ν ¯ 0 T M 1 / 2 ,

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