Affiliations: School of Industrial Engineering, Purdue University,
West Lafayette, Indiana 47907, USA. E-mail: chihyung@purdue.edu | Department of Aeronautics, US Air Force Academy, USAF
Academy, Colorado 80840, USA | School of Aeronautics and Astronautics, Purdue
University, West Lafayette, Indiana 47907, USA
Abstract: Micro devices have been widely used in aerospace engineering for
years. Engineers are interested in applications of micro devices such as
microjets, micro actuators, and micronozzles. The small size nozzles can be
used for attitude adjustment and propulsion of micro-satellites or
mini-spacecraft. In this paper, convergent-divergent micronozzles have been
investigated at supersonic speed with various total pressures and Reynolds
numbers. The throat of the micronozzle is 250 micron wide and the nozzle is
designed as de Laval type. For the measurements, the Reynolds number at the
throat varies from 1200 to 11000 and total pressure varies from 6 psia to 55
psia. Experimental results are obtained with pressure-sensitive paint for
pressure measurement and schlieren imaging for flow visualization. Flow
visualization is a challenge for conventional techniques due to the small
length scales and small depth of the density gradient. A modified schlieren
technique is used to increase the sensitivity by taking the ratio of wind-on
and wind-off images. Pressure-sensitive paint is also used to obtain global
pressure measurement of the flow field and to compare with the schlieren
results.
