# On the efficiency of active flow control with pneumatic jets at Mach numbers between 0.3 and 0.7

On the efficiency of active flow control with pneumatic jets at Mach numbers between 0.3 and 0.7 The project generally investigates the effect of pneumatic vortex generators on flows within a Mach number range of $$M_{\infty} =$$ M ∞ = 0.3–0.7. The efficiency of pneumatic jet actuators to control flow separation was investigated since years. It has been shown that at low Mach numbers the separation of boundary layers can be delayed and avoided, if the velocity ratio between the actuator jet and the free-stream is sufficiently high and the orientation of the jet axis is properly chosen. However, with increasing free-stream velocity, the ratio decreases as w jet must stay below the speed of sound to avoid significant losses due to shock-waves. Thus, the effectivity of slotted pneumatic jet actuators becomes questionable. The scope of this investigation is to identify the potential of this active flow control method at technical relevant Mach numbers. The blowing height is shown as a function of varying Mach number M ∞, velocity ratio w jet/u ∞ and Reynolds number Re set by the total pressure of the test facility p t. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Experiments in Fluids Springer Journals

# On the efficiency of active flow control with pneumatic jets at Mach numbers between 0.3 and 0.7

, Volume 55 (4) – Apr 2, 2014
10 pages

/lp/springer_journal/on-the-efficiency-of-active-flow-control-with-pneumatic-jets-at-mach-vXfAsXh6zG
Publisher
Springer Berlin Heidelberg
Subject
Engineering; Engineering Fluid Dynamics; Fluid- and Aerodynamics; Engineering Thermodynamics, Heat and Mass Transfer
ISSN
0723-4864
eISSN
1432-1114
D.O.I.
10.1007/s00348-014-1683-y
Publisher site
See Article on Publisher Site

### Abstract

The project generally investigates the effect of pneumatic vortex generators on flows within a Mach number range of $$M_{\infty} =$$ M ∞ = 0.3–0.7. The efficiency of pneumatic jet actuators to control flow separation was investigated since years. It has been shown that at low Mach numbers the separation of boundary layers can be delayed and avoided, if the velocity ratio between the actuator jet and the free-stream is sufficiently high and the orientation of the jet axis is properly chosen. However, with increasing free-stream velocity, the ratio decreases as w jet must stay below the speed of sound to avoid significant losses due to shock-waves. Thus, the effectivity of slotted pneumatic jet actuators becomes questionable. The scope of this investigation is to identify the potential of this active flow control method at technical relevant Mach numbers. The blowing height is shown as a function of varying Mach number M ∞, velocity ratio w jet/u ∞ and Reynolds number Re set by the total pressure of the test facility p t.

### Journal

Experiments in FluidsSpringer Journals

Published: Apr 2, 2014

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