Abstract
The measurement and analysis of airflow field is very important in fluid dynamics. For airflow, smoke particles can be
added to visually observe the turbulence phenomena by particle tracking technology, but the effect of smoke particles to
follow the high speed airflow will reduce the measurement accuracy. In recent years, with the advantage of non-contact,
nondestructive, fast and full-field measurement, digital holography has been widely applied in many fields, such as
deformation and vibration analysis, particle characterization, refractive index measurement, and so on. In this paper, we
present a method to measure the airflow field by use of digital holography. A small wind tunnel model made of acrylic
glass is built to control the velocity and direction of airflow. Different shapes of samples such as aircraft wing and
cylinder are placed in the wind tunnel model to produce different forms of flow field. With a Mach-Zehnder
interferometer setup, a series of digital holograms carrying the information of airflow filed distributions in different
states are recorded by CCD camera and corresponding holographic images are numerically reconstructed from the
holograms by computer. Then we can conveniently obtain the velocity or pressure information of the airflow deduced
from the quantitative phase information of holographic images and visually display the airflow filed and its evolution in
the form of a movie. The theory and experiment results show that digital holography is a robust and feasible approach for real-time visualization and analysis of airflow field.
