Numerical simulation of aerodynamic plasma actuator effects

159 Pages·2013·5.85 MB·English

Numerical simulation
of aerodynamic plasma actuator effects

Vom Fachbereich Maschinenbau
an der Technischen Universität Darmstadt
zur Erlangung des Grades eines

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(Dr.-Ing.).

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vorgelegt von

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aus Ilha Solteira, Brasilien

Berichterstatter: Prof. Dr. rer. nat. M. Schäfer
Mitberichterstatter: Prof. Dr-Ing. C. Tropea
Tag der Einreichung: 05.02.2013
Tag der mündlichen Prüfung: 23.04.2013

Darmstadt 2013
D 17

Erklärung

Hiermit versichere ich, die vorliegende Doktorarbeit unter der Betreuung von
Prof. Dr. rer. nat. Michael Schäfer nur mit den angegebenen Hilfsmitteln selbständig
angefertigt zu haben.

Darmstadt, den 5. Februar 2013.

I

to my parents Edson and Marlene

II

Contents

Abstract i

Kurzfassung ii

Preface iii

1. Introduction 1
1.1. Motivation 1
1.2. State of the art 2
1.3. Aims and scope 6
1.4. Thesis organization 7

2. Fluid mechanics background 11
2.1. Equations and important parameters 11
2.2. Transition to turbulence 14
2.3. Linear stability Theory 16

3. Plasma actuators 19
3.1. General description 19
3.2. Numerical representation 20
3.3. Plasma actuators and boundary layer flow control 24

4. Methodologies 27
4.1. Facilities 27
4.2. Numerical solver: FASTEST 27
4.3. Direct Numerical Simulations DNS 28
4.4. Tollmien Schlichting wave excitation 30
4.5. Plasma actuator Body force optimization 32

5. Validation and verification 37
5.1. Base flow 37
5.2. Tollmien Schlichting wave simulations 40
5.3. Plasma actuator simulations 46
5.4. Summary of the numerical procedures 53

6. Boundary layer stabilization 55
6.1. Influence of power supply 55
6.2. Influence of the actuator’s position 67
6.3. Arrays of actuators 73
6.3.1. Arrays of equally distributed power supply 73
6.3.2. Arrays of actuators with different power supply 77
6.4. Multi-frequency disturbances 81
6.5. Summary of the continuous actuation approach 84

7. Active Wave Cancellation 85
7.1. Periodic actuation 85
7.1.1. Influence of the control parameters 85
7.1.2. Optimization of the control parameters 87
7.2. Comparisons with CA 90
7.2.1. Global power efficiency 90
7.2.2. Local effects 94
7.2.3. Downstream effects 99
7.2.4. Linear stability analysis 107
7.3. Summary of cycle actuation techniques 110

8. Combination of effects for flow control purposes 111
8.1. The hypothetical case 111
8.2. Hybrid approach 115
8.3. Summary of flow control techniques
using plasma actuators 120

9. Conclusions 121
9.1 Quantitative analysis of the plasma actuator
aerodynamic effects 121
9.2 Combined effect for wave cancellation 123
9.3 Concluding remarks and future work 123

Bibliography 125

Nomenclature 131

List of figures 135

List of tables 143
Abstract

The present work used an in-house code (FASTEST) for solving the
incompressible Navier-Stokes equations with Finite Volume Method applied to
the flow over a flat plate influenced by plasma actuators. The actuators were
modeled using experimental data (from PIV) for a precise evaluation of the
plasma body force and its fluid mechanic effects. This method is proven and
found to have a good accuracy suitable for a quantitative analysis of the
proposed test cases. Tollmien-Schlichting waves were artificially excited
upstream the actuators position. The waves develop downstream of the
excitation point and are amplified in certain frequency modes. The use of plasma
actuators can attenuate or cancel the Tollmien-Schlichting waves. This process
can be used for turbulence delay and reduction of drag coefficients in aircraft
wings. Several modes of operation of the plasma actuators were tested in
different arrangements and power supply. For cycle operational mode of the
plasma actuator, one sensor was used a few millimeters downstream the actuator
and the setup parameters are optimized with the help of an optimization
algorithm. Linear Stability Analysis was also performed with the data obtained
from Direct Numerical Simulations to investigate the influence of the actuator in
the flow stability proprieties.

i