Abstract

Line-of-sight measurements of velocity, temperature, pressure, density, and mass flux were performed in a transient shock tube flow using three laser absorption schemes. All methods employed an intracavity-doubled ring dye laser tuned to an OH transition in the A2+X2Π (0,0) band at 306 nm. In the first scheme, the gas was labeled by 193.3-nm excimer photolysis of H2O, and the passage of the generated OH was detected downstream. In the second method, the laser was tuned at a rate of 3 kHz over the R1(7) and R1(11) line pair, and absorption was simultaneously monitored at 90 and 60° with respect to the flow. Velocity was determined from the Doppler shift of the profiles and the temperature from the intensity ratio of the lines. Pressure was determined from both the magnitude of absorption and the collisional broadening. In the third method, the laser wavelength was fixed at a single frequency, and a continuous measurement of velocity and pressure was obtained using the signals from the two beam paths. All methods gave results which compare favorably to calculated values.

© 1991 Optical Society of America

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References

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  1. G. Smeets, G. Mathieu, “Investigation of Turbulent Boundary Layers and Turbulence in Shock Tubes by Means of Laser Doppler Velocimetry,” in Shock Tubes and Waves, Proceedings, Sixteenth International Symposium on Shock Tubes and Waves, H. Gronig, Ed. (VCH, Aachen, 1987), p. 193.
  2. B. Hiller, R. K. Hanson, “Simultaneous Planar Measurements of Velocity and Pressure Fields in Gas Flows Using Laser-Induced Fluorescence,” Appl. Opt. 27, 33–48 (1988).
    [CrossRef] [PubMed]
  3. A. Goldman, J. R. Gillis, “Spectral Line Parameters for the A2∑–X2Π (0,0) Band of OH for Atmospheric and High Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 25, 111–135 (1981).
    [CrossRef]
  4. E. C. Rea, R. K. Hanson, “Rapid Extended Range Tuning of Single-Mode Ring Dye Lasers,” Appl. Opt. 22, 518–520 (1983).
    [CrossRef] [PubMed]
  5. E. C. Rea, R. K. Hanson, “Rapid Laser-Wavelength Modulation Spectroscopy Used as a Fast Temperature Measurement Technique in Hydrocarbon Combustion,” Appl. Opt. 27, 4454–4464 (1988).
    [CrossRef] [PubMed]
  6. A. Y. Chang, E. C. Rea, R. K. Hanson, “Temperature Measurements in Shock Tubes Using a Laser-Based Absorption Technique,” Appl. Opt. 26, 885–891 (1987).
    [CrossRef] [PubMed]
  7. A. Y. Chang, B. E. Battles, R. K. Hanson, “Simultaneous Measurements of Velocity, Temperature and Pressure Using Rapid CW Wavelength-Modulation Laser-Induced Fluorescence of OH,” Opt. Lett. 15, 706–708 (1990).
    [CrossRef] [PubMed]
  8. S. Cheng, M. Zimmermann, R. B. Miles, “Supersonic-Nitrogen Flow-Field Measurements with the Resonant Doppler Velocimeter,” Appl. Phys. Lett. 43, 143–145 (1983).
    [CrossRef]
  9. A. G. Gaydon, I. R. Hurle, The Shock Tube in High-Temperature Chemical Physics (Reinhold, New York, 1963).
  10. H. Mirels, “Turbulent Boundary Layer Behind Constant Velocity Shock Including Wall Blowing Effects,” AIAA J. 22, 1042–1047 (1984).
    [CrossRef]
  11. H. Mirels, “Flow Nonuniformity in Shock Tubes Operating at Maximum Test Times,” Phys. Fluids 9, 1907–1912 (1966).
    [CrossRef]
  12. W. C. Gardiner, B. F. Walker, C. B. Wakefield, “Mathematical Methods for Modelling Chemical Reactions in Shock Waves,” in Shock Waves in Chemistry, A. Lifshitz, Ed. (Marcel Dekker, New York, 1981).
  13. L. R. Boedeker, “Velocity Measurement by H2O Photolysis and Laser-Induced Fluorescence of OH,” Opt. Lett. 14, 473–475 (1989).
    [CrossRef] [PubMed]
  14. D. F. Davidson, A. Y. Chang, K. Kohse-Hoinghaus, R. K. Hanson, “High Temperature Absorption Coefficients of O2, NH3, and H2O for Broadband ArF Excimer Laser Radiation,” J. Quant. Spectrosc. Radiat. Transfer 42, 267–278 (1989).
    [CrossRef]
  15. D. F. Davidson, A. Y. Chang, R. K. Hanson, “Laser Photolysis Shock Tube for Combustion Kinetics Studies,” in Twenty-second International Symposium on Combustion (The Combustion Institute, Pittsburgh, 1985), p. 1877.
  16. J. Warnatz, “Rate Coefficients in the C/H/O System,” in Combustion Chemistry, W. C. Gardiner, Ed. (Springer-Verlag, New York, 1984), Chap. 5.
    [CrossRef]
  17. R. J. Kee, J. A. Miller, T. H. Jefferson, “Chemkin: A General-Purpose Problem-Independent, Transportable Fortran Chemical Kinetics Code Package,” Sandia National Laboratory Report SAND80-8003 (1980).
  18. I. L. Chidsey, D. R. Crosley, “Calculated Rotational Transition Probabilities for the A-X System of OH,” J. Quant. Spectrosc. Radiat. Transfer 23, 187–199 (1980).
    [CrossRef]
  19. G. H. Dieke, H. M. Crosswhite, “The Ultraviolet Bands of OH,” J. Quant. Spectrosc. Radiat. Transfer 2, 97–199 (1962).
    [CrossRef]
  20. E. C. Rea, A. Y. Chang, R. K. Hanson, “Shock Tube Study of Pressure Broadening of the A2∑+–X2Π− (0,0) Band of OH by Ar and N2,” J. Quant. Spectrosc. Radiat. Transfer 37, 117–127 (1987).
    [CrossRef]
  21. B. Shirinzadeh, D. M. Bakalyar, C. C. Wang, “Measurement of Collision-Induced Shift and Broadening of the Ultraviolet Transitions of OH,” J. Chem. Phys. 82, 2877–2879 (1985).
    [CrossRef]

1990 (1)

1989 (2)

L. R. Boedeker, “Velocity Measurement by H2O Photolysis and Laser-Induced Fluorescence of OH,” Opt. Lett. 14, 473–475 (1989).
[CrossRef] [PubMed]

D. F. Davidson, A. Y. Chang, K. Kohse-Hoinghaus, R. K. Hanson, “High Temperature Absorption Coefficients of O2, NH3, and H2O for Broadband ArF Excimer Laser Radiation,” J. Quant. Spectrosc. Radiat. Transfer 42, 267–278 (1989).
[CrossRef]

1988 (2)

1987 (2)

A. Y. Chang, E. C. Rea, R. K. Hanson, “Temperature Measurements in Shock Tubes Using a Laser-Based Absorption Technique,” Appl. Opt. 26, 885–891 (1987).
[CrossRef] [PubMed]

E. C. Rea, A. Y. Chang, R. K. Hanson, “Shock Tube Study of Pressure Broadening of the A2∑+–X2Π− (0,0) Band of OH by Ar and N2,” J. Quant. Spectrosc. Radiat. Transfer 37, 117–127 (1987).
[CrossRef]

1985 (1)

B. Shirinzadeh, D. M. Bakalyar, C. C. Wang, “Measurement of Collision-Induced Shift and Broadening of the Ultraviolet Transitions of OH,” J. Chem. Phys. 82, 2877–2879 (1985).
[CrossRef]

1984 (1)

H. Mirels, “Turbulent Boundary Layer Behind Constant Velocity Shock Including Wall Blowing Effects,” AIAA J. 22, 1042–1047 (1984).
[CrossRef]

1983 (2)

S. Cheng, M. Zimmermann, R. B. Miles, “Supersonic-Nitrogen Flow-Field Measurements with the Resonant Doppler Velocimeter,” Appl. Phys. Lett. 43, 143–145 (1983).
[CrossRef]

E. C. Rea, R. K. Hanson, “Rapid Extended Range Tuning of Single-Mode Ring Dye Lasers,” Appl. Opt. 22, 518–520 (1983).
[CrossRef] [PubMed]

1981 (1)

A. Goldman, J. R. Gillis, “Spectral Line Parameters for the A2∑–X2Π (0,0) Band of OH for Atmospheric and High Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 25, 111–135 (1981).
[CrossRef]

1980 (1)

I. L. Chidsey, D. R. Crosley, “Calculated Rotational Transition Probabilities for the A-X System of OH,” J. Quant. Spectrosc. Radiat. Transfer 23, 187–199 (1980).
[CrossRef]

1966 (1)

H. Mirels, “Flow Nonuniformity in Shock Tubes Operating at Maximum Test Times,” Phys. Fluids 9, 1907–1912 (1966).
[CrossRef]

1962 (1)

G. H. Dieke, H. M. Crosswhite, “The Ultraviolet Bands of OH,” J. Quant. Spectrosc. Radiat. Transfer 2, 97–199 (1962).
[CrossRef]

Bakalyar, D. M.

B. Shirinzadeh, D. M. Bakalyar, C. C. Wang, “Measurement of Collision-Induced Shift and Broadening of the Ultraviolet Transitions of OH,” J. Chem. Phys. 82, 2877–2879 (1985).
[CrossRef]

Battles, B. E.

Boedeker, L. R.

Chang, A. Y.

A. Y. Chang, B. E. Battles, R. K. Hanson, “Simultaneous Measurements of Velocity, Temperature and Pressure Using Rapid CW Wavelength-Modulation Laser-Induced Fluorescence of OH,” Opt. Lett. 15, 706–708 (1990).
[CrossRef] [PubMed]

D. F. Davidson, A. Y. Chang, K. Kohse-Hoinghaus, R. K. Hanson, “High Temperature Absorption Coefficients of O2, NH3, and H2O for Broadband ArF Excimer Laser Radiation,” J. Quant. Spectrosc. Radiat. Transfer 42, 267–278 (1989).
[CrossRef]

A. Y. Chang, E. C. Rea, R. K. Hanson, “Temperature Measurements in Shock Tubes Using a Laser-Based Absorption Technique,” Appl. Opt. 26, 885–891 (1987).
[CrossRef] [PubMed]

E. C. Rea, A. Y. Chang, R. K. Hanson, “Shock Tube Study of Pressure Broadening of the A2∑+–X2Π− (0,0) Band of OH by Ar and N2,” J. Quant. Spectrosc. Radiat. Transfer 37, 117–127 (1987).
[CrossRef]

D. F. Davidson, A. Y. Chang, R. K. Hanson, “Laser Photolysis Shock Tube for Combustion Kinetics Studies,” in Twenty-second International Symposium on Combustion (The Combustion Institute, Pittsburgh, 1985), p. 1877.

Cheng, S.

S. Cheng, M. Zimmermann, R. B. Miles, “Supersonic-Nitrogen Flow-Field Measurements with the Resonant Doppler Velocimeter,” Appl. Phys. Lett. 43, 143–145 (1983).
[CrossRef]

Chidsey, I. L.

I. L. Chidsey, D. R. Crosley, “Calculated Rotational Transition Probabilities for the A-X System of OH,” J. Quant. Spectrosc. Radiat. Transfer 23, 187–199 (1980).
[CrossRef]

Crosley, D. R.

I. L. Chidsey, D. R. Crosley, “Calculated Rotational Transition Probabilities for the A-X System of OH,” J. Quant. Spectrosc. Radiat. Transfer 23, 187–199 (1980).
[CrossRef]

Crosswhite, H. M.

G. H. Dieke, H. M. Crosswhite, “The Ultraviolet Bands of OH,” J. Quant. Spectrosc. Radiat. Transfer 2, 97–199 (1962).
[CrossRef]

Davidson, D. F.

D. F. Davidson, A. Y. Chang, K. Kohse-Hoinghaus, R. K. Hanson, “High Temperature Absorption Coefficients of O2, NH3, and H2O for Broadband ArF Excimer Laser Radiation,” J. Quant. Spectrosc. Radiat. Transfer 42, 267–278 (1989).
[CrossRef]

D. F. Davidson, A. Y. Chang, R. K. Hanson, “Laser Photolysis Shock Tube for Combustion Kinetics Studies,” in Twenty-second International Symposium on Combustion (The Combustion Institute, Pittsburgh, 1985), p. 1877.

Dieke, G. H.

G. H. Dieke, H. M. Crosswhite, “The Ultraviolet Bands of OH,” J. Quant. Spectrosc. Radiat. Transfer 2, 97–199 (1962).
[CrossRef]

Gardiner, W. C.

W. C. Gardiner, B. F. Walker, C. B. Wakefield, “Mathematical Methods for Modelling Chemical Reactions in Shock Waves,” in Shock Waves in Chemistry, A. Lifshitz, Ed. (Marcel Dekker, New York, 1981).

Gaydon, A. G.

A. G. Gaydon, I. R. Hurle, The Shock Tube in High-Temperature Chemical Physics (Reinhold, New York, 1963).

Gillis, J. R.

A. Goldman, J. R. Gillis, “Spectral Line Parameters for the A2∑–X2Π (0,0) Band of OH for Atmospheric and High Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 25, 111–135 (1981).
[CrossRef]

Goldman, A.

A. Goldman, J. R. Gillis, “Spectral Line Parameters for the A2∑–X2Π (0,0) Band of OH for Atmospheric and High Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 25, 111–135 (1981).
[CrossRef]

Hanson, R. K.

A. Y. Chang, B. E. Battles, R. K. Hanson, “Simultaneous Measurements of Velocity, Temperature and Pressure Using Rapid CW Wavelength-Modulation Laser-Induced Fluorescence of OH,” Opt. Lett. 15, 706–708 (1990).
[CrossRef] [PubMed]

D. F. Davidson, A. Y. Chang, K. Kohse-Hoinghaus, R. K. Hanson, “High Temperature Absorption Coefficients of O2, NH3, and H2O for Broadband ArF Excimer Laser Radiation,” J. Quant. Spectrosc. Radiat. Transfer 42, 267–278 (1989).
[CrossRef]

B. Hiller, R. K. Hanson, “Simultaneous Planar Measurements of Velocity and Pressure Fields in Gas Flows Using Laser-Induced Fluorescence,” Appl. Opt. 27, 33–48 (1988).
[CrossRef] [PubMed]

E. C. Rea, R. K. Hanson, “Rapid Laser-Wavelength Modulation Spectroscopy Used as a Fast Temperature Measurement Technique in Hydrocarbon Combustion,” Appl. Opt. 27, 4454–4464 (1988).
[CrossRef] [PubMed]

E. C. Rea, A. Y. Chang, R. K. Hanson, “Shock Tube Study of Pressure Broadening of the A2∑+–X2Π− (0,0) Band of OH by Ar and N2,” J. Quant. Spectrosc. Radiat. Transfer 37, 117–127 (1987).
[CrossRef]

A. Y. Chang, E. C. Rea, R. K. Hanson, “Temperature Measurements in Shock Tubes Using a Laser-Based Absorption Technique,” Appl. Opt. 26, 885–891 (1987).
[CrossRef] [PubMed]

E. C. Rea, R. K. Hanson, “Rapid Extended Range Tuning of Single-Mode Ring Dye Lasers,” Appl. Opt. 22, 518–520 (1983).
[CrossRef] [PubMed]

D. F. Davidson, A. Y. Chang, R. K. Hanson, “Laser Photolysis Shock Tube for Combustion Kinetics Studies,” in Twenty-second International Symposium on Combustion (The Combustion Institute, Pittsburgh, 1985), p. 1877.

Hiller, B.

Hurle, I. R.

A. G. Gaydon, I. R. Hurle, The Shock Tube in High-Temperature Chemical Physics (Reinhold, New York, 1963).

Jefferson, T. H.

R. J. Kee, J. A. Miller, T. H. Jefferson, “Chemkin: A General-Purpose Problem-Independent, Transportable Fortran Chemical Kinetics Code Package,” Sandia National Laboratory Report SAND80-8003 (1980).

Kee, R. J.

R. J. Kee, J. A. Miller, T. H. Jefferson, “Chemkin: A General-Purpose Problem-Independent, Transportable Fortran Chemical Kinetics Code Package,” Sandia National Laboratory Report SAND80-8003 (1980).

Kohse-Hoinghaus, K.

D. F. Davidson, A. Y. Chang, K. Kohse-Hoinghaus, R. K. Hanson, “High Temperature Absorption Coefficients of O2, NH3, and H2O for Broadband ArF Excimer Laser Radiation,” J. Quant. Spectrosc. Radiat. Transfer 42, 267–278 (1989).
[CrossRef]

Mathieu, G.

G. Smeets, G. Mathieu, “Investigation of Turbulent Boundary Layers and Turbulence in Shock Tubes by Means of Laser Doppler Velocimetry,” in Shock Tubes and Waves, Proceedings, Sixteenth International Symposium on Shock Tubes and Waves, H. Gronig, Ed. (VCH, Aachen, 1987), p. 193.

Miles, R. B.

S. Cheng, M. Zimmermann, R. B. Miles, “Supersonic-Nitrogen Flow-Field Measurements with the Resonant Doppler Velocimeter,” Appl. Phys. Lett. 43, 143–145 (1983).
[CrossRef]

Miller, J. A.

R. J. Kee, J. A. Miller, T. H. Jefferson, “Chemkin: A General-Purpose Problem-Independent, Transportable Fortran Chemical Kinetics Code Package,” Sandia National Laboratory Report SAND80-8003 (1980).

Mirels, H.

H. Mirels, “Turbulent Boundary Layer Behind Constant Velocity Shock Including Wall Blowing Effects,” AIAA J. 22, 1042–1047 (1984).
[CrossRef]

H. Mirels, “Flow Nonuniformity in Shock Tubes Operating at Maximum Test Times,” Phys. Fluids 9, 1907–1912 (1966).
[CrossRef]

Rea, E. C.

Shirinzadeh, B.

B. Shirinzadeh, D. M. Bakalyar, C. C. Wang, “Measurement of Collision-Induced Shift and Broadening of the Ultraviolet Transitions of OH,” J. Chem. Phys. 82, 2877–2879 (1985).
[CrossRef]

Smeets, G.

G. Smeets, G. Mathieu, “Investigation of Turbulent Boundary Layers and Turbulence in Shock Tubes by Means of Laser Doppler Velocimetry,” in Shock Tubes and Waves, Proceedings, Sixteenth International Symposium on Shock Tubes and Waves, H. Gronig, Ed. (VCH, Aachen, 1987), p. 193.

Wakefield, C. B.

W. C. Gardiner, B. F. Walker, C. B. Wakefield, “Mathematical Methods for Modelling Chemical Reactions in Shock Waves,” in Shock Waves in Chemistry, A. Lifshitz, Ed. (Marcel Dekker, New York, 1981).

Walker, B. F.

W. C. Gardiner, B. F. Walker, C. B. Wakefield, “Mathematical Methods for Modelling Chemical Reactions in Shock Waves,” in Shock Waves in Chemistry, A. Lifshitz, Ed. (Marcel Dekker, New York, 1981).

Wang, C. C.

B. Shirinzadeh, D. M. Bakalyar, C. C. Wang, “Measurement of Collision-Induced Shift and Broadening of the Ultraviolet Transitions of OH,” J. Chem. Phys. 82, 2877–2879 (1985).
[CrossRef]

Warnatz, J.

J. Warnatz, “Rate Coefficients in the C/H/O System,” in Combustion Chemistry, W. C. Gardiner, Ed. (Springer-Verlag, New York, 1984), Chap. 5.
[CrossRef]

Zimmermann, M.

S. Cheng, M. Zimmermann, R. B. Miles, “Supersonic-Nitrogen Flow-Field Measurements with the Resonant Doppler Velocimeter,” Appl. Phys. Lett. 43, 143–145 (1983).
[CrossRef]

AIAA J. (1)

H. Mirels, “Turbulent Boundary Layer Behind Constant Velocity Shock Including Wall Blowing Effects,” AIAA J. 22, 1042–1047 (1984).
[CrossRef]

Appl. Opt. (4)

Appl. Phys. Lett. (1)

S. Cheng, M. Zimmermann, R. B. Miles, “Supersonic-Nitrogen Flow-Field Measurements with the Resonant Doppler Velocimeter,” Appl. Phys. Lett. 43, 143–145 (1983).
[CrossRef]

J. Chem. Phys. (1)

B. Shirinzadeh, D. M. Bakalyar, C. C. Wang, “Measurement of Collision-Induced Shift and Broadening of the Ultraviolet Transitions of OH,” J. Chem. Phys. 82, 2877–2879 (1985).
[CrossRef]

J. Quant. Spectrosc. Radiat. Transfer (5)

A. Goldman, J. R. Gillis, “Spectral Line Parameters for the A2∑–X2Π (0,0) Band of OH for Atmospheric and High Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 25, 111–135 (1981).
[CrossRef]

D. F. Davidson, A. Y. Chang, K. Kohse-Hoinghaus, R. K. Hanson, “High Temperature Absorption Coefficients of O2, NH3, and H2O for Broadband ArF Excimer Laser Radiation,” J. Quant. Spectrosc. Radiat. Transfer 42, 267–278 (1989).
[CrossRef]

I. L. Chidsey, D. R. Crosley, “Calculated Rotational Transition Probabilities for the A-X System of OH,” J. Quant. Spectrosc. Radiat. Transfer 23, 187–199 (1980).
[CrossRef]

G. H. Dieke, H. M. Crosswhite, “The Ultraviolet Bands of OH,” J. Quant. Spectrosc. Radiat. Transfer 2, 97–199 (1962).
[CrossRef]

E. C. Rea, A. Y. Chang, R. K. Hanson, “Shock Tube Study of Pressure Broadening of the A2∑+–X2Π− (0,0) Band of OH by Ar and N2,” J. Quant. Spectrosc. Radiat. Transfer 37, 117–127 (1987).
[CrossRef]

Opt. Lett. (2)

Phys. Fluids (1)

H. Mirels, “Flow Nonuniformity in Shock Tubes Operating at Maximum Test Times,” Phys. Fluids 9, 1907–1912 (1966).
[CrossRef]

Other (6)

W. C. Gardiner, B. F. Walker, C. B. Wakefield, “Mathematical Methods for Modelling Chemical Reactions in Shock Waves,” in Shock Waves in Chemistry, A. Lifshitz, Ed. (Marcel Dekker, New York, 1981).

D. F. Davidson, A. Y. Chang, R. K. Hanson, “Laser Photolysis Shock Tube for Combustion Kinetics Studies,” in Twenty-second International Symposium on Combustion (The Combustion Institute, Pittsburgh, 1985), p. 1877.

J. Warnatz, “Rate Coefficients in the C/H/O System,” in Combustion Chemistry, W. C. Gardiner, Ed. (Springer-Verlag, New York, 1984), Chap. 5.
[CrossRef]

R. J. Kee, J. A. Miller, T. H. Jefferson, “Chemkin: A General-Purpose Problem-Independent, Transportable Fortran Chemical Kinetics Code Package,” Sandia National Laboratory Report SAND80-8003 (1980).

G. Smeets, G. Mathieu, “Investigation of Turbulent Boundary Layers and Turbulence in Shock Tubes by Means of Laser Doppler Velocimetry,” in Shock Tubes and Waves, Proceedings, Sixteenth International Symposium on Shock Tubes and Waves, H. Gronig, Ed. (VCH, Aachen, 1987), p. 193.

A. G. Gaydon, I. R. Hurle, The Shock Tube in High-Temperature Chemical Physics (Reinhold, New York, 1963).

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Figures (17)

Fig. 1
Fig. 1

Schematic of the time-of-flight scheme: A, aperture; F, filter; Det., silicon photodetector. The separation between the photolysis beam path and the OH probe beam path is 195 mm. The OH labeled gas volume is 3 mm wide.

Fig. 2
Fig. 2

Example of the excimer laser time-of-flight absorption data. The shock conditions are Mshock = 4.13, Vgas = 944 m/s, T = 1795 K, P = 0.41 atm. The absorption spike at 280 μs is caused by steering the probe beam due to the passage of the shock front. The time the excimer laser is fired is evident from the noise spike at 567 μs. The OH produced by the excimer photolysis pulse is centered at 770 μs. The inferred gas velocity is 961 m/s.

Fig. 3
Fig. 3

Measured core gas velocity vs calculated velocity for the time-of-flight method: solid circles, velocities measured with a mean time delay of 500 μs after the passage of the incident shock; solid line, 1-D shock calculation.

Fig. 4
Fig. 4

Schematic of the rapid-tuning measurement scheme: A, aperture; F, filter; Det., silicon photodetector. The fixed-frequency measurement method uses the same arrangement, except that the tuning rhombs in the laser cavity are replaced by an etalon and the flat flame burner is used as an additional wavelength reference.

Fig. 5
Fig. 5

Example of the raw rapid-tuning data showing repeated wavelength scan across the OH R1(7) and R1(11) line pair centered at 32,625.4 cm−1 acquired in the gas behind an incident shock wave. The R1(7) line is the higher of the two peaks. The shock conditions are Mshock = 3.73, Vgas = 836 m/s, T = 1540 K, P = 0.56 atm. Upper panel: I0, signal and absorption signal from the probe beam at 90° to the flow. Center panel: I0 signal and absorption signal from the probe beam at 60° to the flow. Bottom panel: etalon signal of the undoubted (visible) dye laser output. The disturbance in the absorption at 300 μs of the perpendicular signal is a result of beam steering by the passage of the shock front.

Fig. 6
Fig. 6

Example of a pair of profiles from the data of Fig. 5. Solid line, profile acquired at 60°; dashed line, profile acquired at 90°. The time domain of the raw data has been converted to frequency and the peak amplitude normalized to unity. The Doppler shift between the two traces is a −1.423-GHz shift, and the line pair intensity ratios are 0.420 and 0.426. The inferred temperatures and gas velocity are 1560 K (90°), 1580 K (60°), and 872 m/s.

Fig. 7
Fig. 7

Measured line-of-sight gas velocity vs calculated velocity for the rapid-tuning method: solid circles, velocities derived from the first reducible pair of profiles; solid diamonds, velocities derived from the second reducible pair of profiles; solid line, 1-D shock calculation.

Fig. 8
Fig. 8

Measured temperature vs calculated temperature for the rapid-tuning method: solid and open circles, temperature derived from the first reducible profiles of the 90 and 60° beams; solid and open diamonds, temperature derived from the second reducible profiles of the 90 and 60° beams; solid line, 1-D shock calculation including a correction for chemistry.

Fig. 9
Fig. 9

Measured total pressure from the magnitude of the absorption vs calculated pressure for the rapid-tuning method: solid and open circles, pressure derived from the first reducible profiles of the 90 and 60° beams; solid and open diamonds, pressure derived from the second reducible profiles of the 90 and 60° beams; solid line, 1-D shock calculation.

Fig. 10
Fig. 10

Measured total pressure from collision broadening vs calculated pressure for the rapid-tuning method: solid and open circles, pressure derived from the first reducible profiles of the 90 and 60° beams; solid and open diamonds, pressure derived from the second reducible profiles of the 90 and 60° beams; solid line, 1-D shock calculation.

Fig. 11
Fig. 11

Measured mass density from the magnitude of the absorption vs calculated density for the rapid-tuning method: solid and open circles, density derived from the first reducible profiles of the 90 and 60° beams. Solid and open diamonds, density derived from the second reducible profiles of the 90 and 60° beams. Solid line, 1-D shock calculation.

Fig. 12
Fig. 12

Measured mass flux vs calculated mass flux for the rapid-tuning method. Density and velocity are determined simultaneously for each shock: solid circles, mass flux derived from the first reducible pair of profiles; solid diamonds, mass flux determined from the second reducible pair of profiles; solid line, 1-D calculation shock calculation including correction for chemistry.

Fig. 13
Fig. 13

Example of fixed-frequency data. The shock conditions are Mshock = 5.42, Vgas = 1267 ms, T = 2900 K, P = 0.19 atm. Absorption of the probe beam at 60° (oblique) to the flow is less than that of the 90° (perpendicular) absorption. Zero time, arrival of the incident shock at 90° view ports. The laser wavelength is shifted +2.0 GHz off of the line center of the R1(5) line. The slight delay of the rise in the absorption of the 90° probe signal is a result of the ignition delay for the H2/O2/N2O mixture at this temperature. The early start of the absorption and the slower rise to the plateau absorption value on the 60° probe beam are a result of the angled sampling path of this beam.

Fig. 14
Fig. 14

Velocity vs time for the fixed-frequency data of Fig. 13. Solid line, velocity inferred from the ratio of the absorptions and the calculated temperature. The average measured velocity was 1274 m/s. Dashed line, calculated velocity of 1267 m/s.

Fig. 15
Fig. 15

Pressure vs time for the fixed-frequency data of Fig. 13. Solid line, pressure inferred from the analysis of the perpendicular absorption and the calculated temperature. The average measured pressure was 0.205 atm. Dashed line, calculated pressure of 0.19 atm.

Fig. 16
Fig. 16

Measured gas velocity vs calculated gas velocity for the fixed-frequency method: solid circles, fixed-frequency velocities averaged from the shock front to the contact surface; error bars, one standard deviation of the measured velocity profile from the mean velocity for each shock; solid line, 1-D shock calculation.

Fig. 17
Fig. 17

Measured total pressure vs calculated pressure for the fixed-frequency method: solid circles, pressures determined at 500 μs behind the incident shock; solid line, 1-D shock calculation.

Equations (9)

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Δ I / I 0 = 1 - exp ( - k ν P abs L ) ,
k ν = ( π e 2 / m c 2 ) ( N L 273.15 / T ) f B f Φ ( ν ) ,
Δ ν / ν = V gas cos θ / c ,
V gas ( m / s ) = 2 × 306.5 Δ ν rel ( GHz ) .
R = f ( 11 ) / f ( 7 ) f B ( 11 ) / f B ( 7 ) .
R = C exp ( - B / T ) .
a = 0.14 P ( T / 1600 ) 1.3 .
ρ = P / R T ,
W = ρ V gas .

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