Experiments in Fluids

, Volume 5, Issue 6, pp 372–380

Measurements of temperature, density, pressure, and their fluctuations in supersonic turbulence using laser-induced fluorescence

  • K. P. Gross
  • R. L. McKenzie
  • P. Logan
Article

DOI: 10.1007/BF00264400

Cite this article as:
Gross, K.P., McKenzie, R.L. & Logan, P. Experiments in Fluids (1987) 5: 372. doi:10.1007/BF00264400

Abstract

A laser-induced fluorescence (LIF) method has been developed that provides simultaneous measurements of temperature, density, and their fluctuations owing to turbulence in unheated compressible flows. Pressure and its fluctuations are also deduced using the equation of state. Fluorescence is induced in nitric oxide that has been seeded into a nitrogen flow in concentrations of 100 ppm. Measurements are obtained from each laser pulse, with a spatial resolution of 1 mm and a temporal resolution of 125 ns. The method was applied to a supersonic, turbulent, boundary-layer flow with a free-stream Mach number of 2. For stream conditions in the range from 150–300 K and 0.3–1 atm, temperature is measured with an uncertainty of approximately 1% rms, while density and pressure uncertainties are approximately 2% rms.

List of symbols

Blu

Einstein B-coefficient for transitions from state |l〉 to state u〉

c

speed of light

CD

calibration factor for density measurement [see Eq. (20)]

CT

calibration factor for temperature measurement [see Eq. (18)]

Clu

collision broadening function constant [see Eq. (14)]

d

Voigt parameter [see Eq. (9)]

Ef

fluorescence energy per pulse

E0

laser pulse energy

El

energy of molecular state |l

Fi

spectral function for laser i (i = 1, 2) [see Eq. (17)]

gl

degeneracy of state |l

Glu

spectral convolution integral [see Eq. (3)]

h

Plank's constant

J′, J

upper and lower rotational quantum numbers respectively

k

Boltzmann's constant

L

length of observed sample volume

mf

molecular mass per molecule of the fluorescent species

M

free-stream Mach number

N

total number density

Ni

number density in state |i

Nl*

number density in state |l〉 at thermal equilibrium

p, p

Voigt parameters [see Eqs. (10) and (15)]

P

pressure

Reδ

Reynolds number based on boundary layer thickness

Si, Si

sample and reference signals respectively, from las i

t

time

T

kinetic temperature

v′, v

upper and lower vibrational quantum numbers respectively

V(p, d)

Voigt function

Xi

mole fraction of species i

Z

partition function

δ

boundary layer thickness

δv

detuning frequency

Δv

spectral width (full width at half maximum)

ζJ″, J′

rotational line-strength factor

v

frequency

v

average band frequency

τ0

collisional decay time

τf

fluorescence decay time

τT

total radiative decay time

τui

quenching time of state |u〉 by species i

Φ(v0, v)

spectral distribution function centered at frequency

Subscripts and superscripts

D

Doppler

G

Gaussian

lu

state |l〉 to state |u〉 transition

L

Lorentzian

r

reference condition

0

property of the laser

t

flow stagnation condition

flow free-stream condition

Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • K. P. Gross
    • 1
  • R. L. McKenzie
    • 2
  • P. Logan
    • 3
  1. 1.Polyatomics Research InstituteMountain ViewUSA
  2. 2.Ames Research CenterMoffett FieldUSA
  3. 3.Dept. of Aeronautics and AstronauticsStanford UniversityStanfordUSA
  4. 4.Tencor InstrumentsMountain ViewUSA

Personalised recommendations