Active control of base pressure in suddenly expanded flow for area ratio 4.84
Airflow from convergent-divergent axi-symmetric nozzles expanded suddenly into circular duct of larger cross-sectional area than that of nozzle exit area are studied experimentally, focusing attention on the base pressure and the flow development in the enlarged duct. Micro-jets of 1 mm orifice di...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
International Journal of Engineering Science and Technology" (IJEST™)
2012
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/49825/ http://irep.iium.edu.my/49825/ http://irep.iium.edu.my/49825/1/IJEST12-04-05-149.pdf |
| Summary: | Airflow from convergent-divergent axi-symmetric nozzles expanded suddenly into circular duct of
larger cross-sectional area than that of nozzle exit area are studied experimentally, focusing attention on the base
pressure and the flow development in the enlarged duct. Micro-jets of 1 mm orifice diameter located at 900
intervals along a pitch circle diameter (pcd) 1.3 times the nozzle exit diameter were employed as the controller
of the base pressure. The tests are conducted for Mach numbers 1.87, 2.2 and 2.58. The area ratio of the present
study is 4.84. The length-to-diameter ratio of the suddenly expanded duct is varied from 10 to 1 and nozzle
pressure ratio (NPR) in the range 3 to 11. It is found that the active control in the form of blowing through small
orifices (micro jets) are effective in controlling the base pressure field and even do not augment the flow field in
the duct. An increase of 45 percent in base pressure was achieved for certain combination of parameters of the
present study. |
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