Flow visualization and pressure measurement in micronozzles
- 129 Downloads
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.
KeywordsVisualization Micronozzle Pressure sensitive-paint Schlieren
Unable to display preview. Download preview PDF.
- Bayt, R. L. and Breuer, K. S., Viscous Effects in Supersonic MEMS-fabricated micronozzles, 3rd ASME Microfluid Symposium (Anaheim, CA.), (1998).Google Scholar
- Bertin, J. J., Aerodynamics for Engineers, 4th Edition, (2001), Prentice Hall, NJ.Google Scholar
- Buoni, M., Dietz, D., Aslam, K. and Subramaniam, V. V., Simulation of Compressible Gas Flow in a Micronozzle, 35th AIAA Thermophysics Conference (Anahiem, CA.), AIAA-2001-3073 (2001).Google Scholar
- Choudhuri, A. R., Baird, B., Gollahalli, S. R. and Schneider, S. J., Effects of Geometry and Ambient Pressure on Micronozzle Flow, 37th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit (Salt Lake City, Utah), AIAA-2001-3331 (2001).Google Scholar
- Engler, R. H., Fey, U., Henne, U., Klein, Chr. and Scahs, W. E., Quantitative Wind Tunnel Studies Using Pressure- and Temperature Sensitive Paints, Journal of Visualization, 8-3 (2005), 277–284.Google Scholar
- Huang, C.-Y., Sakaue, H., Gregory, J. W. and Sullivan, J. P., Molecular Sensors for MEMS, 40th Aerospace Sciences Meeting & Exhibit (Reno, NV.), AIAA-2002-0256, (2002).Google Scholar
- Huang, C.-Y., Gregory, J. W. and Sullivan, J. P., Microchannel Pressure Measurements Using Molecular Sensors, Journal of Microelectromechanical Systems, (2007a) ( in press).Google Scholar
- Liu, T. and Sullivan, J. P, Pressure and Temperature Sensitive Paints, (2005), Springer-Verlag, Berlin Heidelberg, Germany.Google Scholar