Interaction of fluidic actuators and a flat plate boundarylayer: experiments and first results

Célestin OTTPhD student - 2nd year

ONERA Lille, LAMIH Valenciennes

Thesis director: Laurent KEIRSBULCK – LAMIH UMR CNRS 8201 Valenciennes

ONERA Supervisor : Quentin GALLAS – Onera Lille – DAAA/ELV

Funding: 50% ONERA & 50% LAMIH

2 OTT Célestin – GDR Flow Control – Orléans 2017

Context

Boundary layer detachmentwake turbulences…

• Decreasing performances• Energy losses

Flow control

• Increase global performances by local manipulations

v Flow control

Without flow control With flow control

[1] J. Dandois, "contrôle des decollements par jet synthétique", PhD Thesis, ONERA, 2007

[1] [1]

Motivation

3 OTT Célestin – GDR Flow Control – Orléans 2017

v Highlighting dynamic mechanisms between jets and the turbulent boundary layer

v Definition of a metric of the effectiveness of a flow control solution

v Association flow control target à actuator configuration

v Creation of a experimental data base for future CFD studies

Zone of interest

Continuous Pulsed Synthetic Sweeping

vSelect 2 configurations

vSelect & characterize 4 fluidic actuators

vCharacterization of the boundary layer

vMeasurement of the BL with control solutions

vSpace-time solved measurement :

vPIV 2C&3C

vLDA

vHot wire 1C

vPressure & shear measurement

vPhysical phenomenon analysis

vPIV & Hot Wire maps investigations

vThorough analyses (POD, DMD)

Experimental approach

4 OTT Célestin – GDR Flow Control – Orléans 2017

Progress

v Conception & fabrication

§ hood (30x0.5mm² slot inclined at 45°)

§ Diffuser (3D printed)

§ Sweeping jet actuator (3D printed)

§ Flat plate with sensors

OTT Célestin – GDR Flow Control – Orléans 20175

Wallsensors

HotWire

Characterization (1/4)

v Wind tunnel characterization at 30m/s

𝑺𝑺𝑺𝑺𝑺𝑺 𝑹𝑹𝑹𝑹 𝜹𝜹(𝒎𝒎𝒎𝒎) 𝜽𝜽(𝒎𝒎𝒎𝒎) 𝑹𝑹𝑹𝑹𝜽𝜽 𝒄𝒄𝒇𝒇 𝒖𝒖𝝉𝝉(𝒎𝒎 𝒔𝒔)⁄

FC 576 923 29.5 3.14 6 038 0.0030 1.162

PIV 576 923 26.5 3.85 7 404 0.0029 1.142

v δboundarylayerthickness mmU δ = 99%. UI

v θmommentumthickness(mm)

θ = KUL

UI

M

N1 −

UL

UIdy

v cQwallfrictioncoefficient

cQ = 21𝐾𝐾 ln 𝑅𝑅𝑅𝑅X + 𝐶𝐶

[\

With K=0.384etC=4.127(Coles-Fernholtz formula)

v u]wallfrictionvelocity

u] = UIcQ2

_

Wind tunnels almost identical. Comparisons possible

OTT Célestin – GDR Flow Control – Orléans 20176

• Homogeneity & Umaxchecked

• Relation Pabcd&UdfLgh

kit diffuser+ hood Hot wire measurements

Micro-manometer characterization relation VR <-> Palim

v Characterization on test bench of continuous jet

OTT Célestin – GDR Flow Control – Orléans 20177

Characterization (2/4)

• Umean & F• Relation

Pabcd &F,Uijk

Hot wire characterization

Hot Wire raw data (20 kHz)

OTT Célestin – GDR Flow Control – Orléans 20178

Characterization (3/4)

v Characterization on test bench of sweeping jet

v Characterization in wind tunnel of pulsed & continuous jets (FESTO actuator)

§ Cmmomentumcoefficient

Cm =ρogpUogp

\Sogp12 ρIUI

\SrgQ=

qdUogp12 ρIUI

\SrgQ

VelocityRatio

§ τdelayactuatorsignal − jet

τ=2.5ms

τ

EvolutionofCm = f wxyz

w{

Measurementofτ(ms)forexperimentalsetup

with:𝑆𝑆}~� testveinsectionUjet meanvelocityforcontinuousjet

FC sortie fente

OTT Célestin – GDR Flow Control – Orléans 20179

Characterization (4/4)

First results (1/2)

OTT Célestin – GDR Flow Control – Orléans 2017

v Hot Wire measurement with continuous jet (VR2)

Hot wire scanning Transverse plane boundary layer profile at slot exit

Unsteady ponctual measurementBL profile with average DC

v Hot Wire measurement with pulsed jet (100Hz VR2)V

Raw signal Average duty cycle – phase lock

Localizingthejetimpact

Influenceoffrequency investigations

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Hot wire scanning

First results (2/2)

OTT Célestin – GDR Flow Control – Orléans 2017

[In progress]

v PIV measurement – time solved – for pulsed jet

v 2 Photron cameras§ 1024x1024 pixels § 10kHz§ lens 105mm

v Quantronics Laser§ 1-10kHz§ 527nm – 2x 19 mJ

PROBLEM:• Noparticlesinthejet• Jettooclosetothewall

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Exploratory PIV measurements

OTT Célestin – GDR Flow Control – Orléans 2017

Wallfrictioncontrol

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𝜕𝜕𝑈𝑈𝜕𝜕𝑦𝑦

Up-wind streamlines control

v High Velocity Ratio (low middle veine velocity) v Low Velocity Ratio (high middle veine velocity)

Wind Wind

slot slot

slotslot

Outlooks

OTT Célestin – GDR Flow Control – Orléans 2017

Short Termv Understand and characterize de two “control types”

v Wall friction velocity investigations

v Impact of the type of actuators used

v Impact of VR and frequencies

v Measurements with synthetic and sweeping jet

v Hot wire and 3C PIV measurements and investigations

v Advanced analysis tools (POD & DMD) ?

v Actuators comparison

Middle Termv Second test campaign (in process of definition)

© Onera

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