Active control of suddenly expanded flows from overexpanded nozzles
An experimental investigation was carried out to study the effectiveness of micro-jets to control base pressure in suddenly expanded axi-symmetric ducts. Four micro-jets of 1 mm orifice diameter located at 90$^\circ$ interval along a pitch circle diameter of 1.3 times the nozzle exit diameter...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Walter de Gruyter
2002
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/46690/ http://irep.iium.edu.my/46690/ http://irep.iium.edu.my/46690/ http://irep.iium.edu.my/46690/1/khan_s_a_-_2002_-_active_control_of_suddenly_expanded_flows_from_overexpanded_nozzles.pdf |
| Summary: | An experimental investigation was carried out to study the
effectiveness of micro-jets to control base pressure in suddenly
expanded axi-symmetric ducts. Four micro-jets of 1 mm orifice diameter
located at 90$^\circ$ interval along a pitch circle diameter of 1.3
times the nozzle exit diameter in the base region was
employed as active controls. The Mach numbers of the suddenly
expanded flows were studies 2.0, 2.5 and 3.0. The jets were expanded
suddenly
into an axi-symmetric tube with cross-sectional area 2.56, 3.24, 4.84,
and 6.25 times that of nozzle exit diameter. The length-to-diameter
ratio of the sudden expansion tube was varied from 10 to 1. The jets
were operated at an over expansion level of Pe/Pa = 0.277.
The wall pressure distribution in the suddenly enlarged duct was also
measured. It is found that the micro-jets can serve as active
controllers for
base pressure. Also, the wall pressure distribution is not adversely
influenced by the micro-jets. From the present investigation it is
evident that for a given Mach number and nozzle pressure ratio one can
identify the enlargement length to diameter ratio which will result
in maximum increase/decrease of base pressure. |
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