Characterization of Laser Energy Deposition for Aerodynamic Flow Control

Tierra RollerAerospace Engineering, University of Arizona

Mentor: Dr. Jesse LittleAssistant Professor, Department of Aerospace and Mechanical Engineering,

University of Arizona

Arizona Space Grant ConsortiumApril 18, 2015Phoenix, AZ

2

Acknowledgements

• Research Group Members:• Clark Pederson• Liliana Saldaña• David Akins• Robyn Dawson

• Space Grant Administrators and Mentors• Air Force Office of Scientific Research

3

Flow Control• Flow control:

improves the aerodynamic performance of a surface

• Active: not a permanent alteration of the surface

• Energy deposition: adding energy to the flow

Baseline

Control

Images from Ely and Little, 2013

4

0 5 10 15 20 25 301.8

2

2.2

2.4

2.6

2.8

3

3.2

Wind Tunnel, Laser turned on ~ 5 s

Time (s)

Ve

loc

ity

(m

/s)

Wind Tunnel Test

Trailing edge

High velocity

Low velocity

5

Effect of the Laser

100 200 300 400 500 600 700 800 900 10000.080.09

0.10.110.120.130.140.150.160.170.18

Time of Laser Exposure Effect

Time Laser Has Run (s)

% In

crea

se in

Vel

ocity

6

Schlieren Imaging

• Bending of light through density gradients

• Propagating shock wave associated with the rapid heating of the surface

Shock wave

Low density region

7

Schlieren Imaging Setup

Laser – Plate Interaction

8

Quantitative Results

Shock wave

9

Analysis

• Similar curves• Need better tunnel data

100 200 300 400 500 600 700 800 900 10000.08

0.09

0.1

0.11

0.12

0.13

0.14

0.15

0.16

0.17

0.18

Time of Laser Exposure Effect

Time Laser Has Run (s)%

Inc

rea

se

in V

elo

cit

y

10

Next Steps

• Get a fuller, more accurate curve for velocity change• Run the tunnel test keeping the velocity

measurement in the same location

• Repeat the process with various metals• Steel and copper• Improve wind tunnel testing

11

Thank you

12

Ablation Damage

Permanent damage due to ablation

13

Schlieren Imaging

Image from John and Keith 2006