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Flow Visualization of a Low Density -;
Hypersonic Flow Field ,3LLJ
N. FOUNDS, B. MASSON, and E. JUMPER
USAF, WEAPONS LABORATORY
KIRTLAND AFB, NM
EmWALTERS
UNIVERSITY of NEW MEXICO
ALBUQUERQUE, NM
T. SEGALMAN
ROCKWELL POWER SERVICES CO.
ALBUQUERQUE, NM
AlAA 20th Fluid Dynamics, Plasma Dynamics
and Lasers Conference
Buffalo, New York 1 June 12-14, 1989
For permission to copy or republish, contact the American Institute of Aeronautics and Astronautics
370 L'Enfant Promenade, ., Washington, . 20024
Flow Visualication of a Low Density Hypersonic Flow Field
. Fo~mdst,. Massonf, . Jumpers /f?-%7/37
*, . Segalman**
Abstract
Characteristics of laser induced iodine fluorescence (LITF) in low density hypersonic flows are being
investigated for use as a diagnostic technique. At low pressures, doppler broadening dominates the iodine
absoiption profile producing a fluorescence signal that is primarily temperature and velocity dependent. From
this dependency, a low pressure flow field has the potential to be mapped for its velocity and temperature
fields. The theory for relating iodine emission to the velocity and temperature fields of a hypersonic flow
is discussed in this paper. Experimental observations are made of a fluorescencing free expansion and
qualitatively related to the theory.
Introduction
Laser Induced Iodine Fluorescence (LIIF) has the potential of providing a nseful nonintrusive flow field
diagnostic in chen~icallaser flow fields. The intensity of the Iilwrescence of iodine seeded If F - DF Iirser
flow fields was first studied by Rapagnani and Davis1. The information gained here was qualitative, serving
primarily as a flow field visualization technique in which the iodine seeded in either the secondary fuel or
the primary trip flow could be followed as it mixed and distorted the primary stream. Since the iodine seed
would be