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Trajectory of a synthetic jet issuing into high Reynolds number turbulent boundary layers

Trajectory of a synthetic jet issuing into high Reynolds number turbulent boundary layers
Trajectory of a synthetic jet issuing into high Reynolds number turbulent boundary layers
Synthetic jets are zero-net-mass-flux actuators that can be used in a range of flow control applications. For some applications, the scaling of the trajectory of the jet with actuation and cross-flow parameters is important. This scaling is investigated for changes in the friction Reynolds number, changes in the velocity ratio (defined as the ratio between the mean jet blowing velocity and the free-stream velocity) and changes in the actuation frequency of the jet. A distinctive aspect of this study is the high-Reynolds-number turbulent boundary layers (up to Re = 12 800 ) of the cross-flow. To our knowledge, this is the first study to investigate the effect of the friction Reynolds number of the cross-flow on the trajectory of an (unsteady) jet, as well as the first study to systematically investigate the scaling of the trajectory with actuation frequency. A broad range of parameters is varied (rather than an in-depth investigation of a single parameter) and the results of this study are meant to indicate the relative importance of each parameter rather than the exact influence on the trajectory. Within the range of parameters explored, the critical ones are found to be the velocity ratio as well as a non-dimensional frequency based on the jet actuation frequency, the cross-flow velocity and the jet dimensions. The Reynolds number of the boundary layer is shown to have only a small effect on the trajectory. An expression for the trajectory of the jet is derived from the data, which (in the limit) is consistent with known expressions for the trajectory of a steady jet in a cross-flow.
0022-1120
531-551
Berk, Tim
6d080fa4-abf6-4a81-9e35-178e8454e755
Hutchins, Nicholas
10ef0e3e-266c-4569-90ae-598ed9fb5edd
Marusic, Ivan
e8863dbc-d29e-4087-9269-ea1ef1d63f48
Ganapathisubramani, Bharathram
5e69099f-2f39-4fdd-8a85-3ac906827052
Berk, Tim
6d080fa4-abf6-4a81-9e35-178e8454e755
Hutchins, Nicholas
10ef0e3e-266c-4569-90ae-598ed9fb5edd
Marusic, Ivan
e8863dbc-d29e-4087-9269-ea1ef1d63f48
Ganapathisubramani, Bharathram
5e69099f-2f39-4fdd-8a85-3ac906827052

Berk, Tim, Hutchins, Nicholas, Marusic, Ivan and Ganapathisubramani, Bharathram (2018) Trajectory of a synthetic jet issuing into high Reynolds number turbulent boundary layers. Journal of Fluid Mechanics, 856, 531-551. (doi:10.1017/jfm.2018.734).

Record type: Article

Abstract

Synthetic jets are zero-net-mass-flux actuators that can be used in a range of flow control applications. For some applications, the scaling of the trajectory of the jet with actuation and cross-flow parameters is important. This scaling is investigated for changes in the friction Reynolds number, changes in the velocity ratio (defined as the ratio between the mean jet blowing velocity and the free-stream velocity) and changes in the actuation frequency of the jet. A distinctive aspect of this study is the high-Reynolds-number turbulent boundary layers (up to Re = 12 800 ) of the cross-flow. To our knowledge, this is the first study to investigate the effect of the friction Reynolds number of the cross-flow on the trajectory of an (unsteady) jet, as well as the first study to systematically investigate the scaling of the trajectory with actuation frequency. A broad range of parameters is varied (rather than an in-depth investigation of a single parameter) and the results of this study are meant to indicate the relative importance of each parameter rather than the exact influence on the trajectory. Within the range of parameters explored, the critical ones are found to be the velocity ratio as well as a non-dimensional frequency based on the jet actuation frequency, the cross-flow velocity and the jet dimensions. The Reynolds number of the boundary layer is shown to have only a small effect on the trajectory. An expression for the trajectory of the jet is derived from the data, which (in the limit) is consistent with known expressions for the trajectory of a steady jet in a cross-flow.

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Trajectory of a synthetic jet issuing into high Reynolds number turbulent boundary layers - Accepted Manuscript
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Accepted/In Press date: 7 September 2018
e-pub ahead of print date: 5 October 2018
Published date: 10 December 2018

Identifiers

Local EPrints ID: 424249
URI: https://eprints.soton.ac.uk/id/eprint/424249
ISSN: 0022-1120
PURE UUID: 896976c7-3a1e-421f-afbd-a3b969145b89
ORCID for Bharathram Ganapathisubramani: ORCID iD orcid.org/0000-0001-9817-0486

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Date deposited: 05 Oct 2018 11:35
Last modified: 14 Mar 2019 05:03

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