15 - 17 september 2004 4th European Micro-UAV meeting Toulouse Micro engines for micro drones propulsion Jo

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15 - 17 september 2004 4th European Micro-UAV
meetingToulouseMicro engines for micro drones
propulsionJoël Guidez, Clément Dumand, Olivier
Dessornes, Yves Ribaud
Office National dÉtudes et de Recherches
Aérospatiales
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Outline of the presentation

• 1/ Introduction micro-systems
• 2/ Application to micro-drones
• 3/ Energetics micro-systems
• 4/ Micro-turbine
• 5/ Conclusion and perspectives

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1 / INTRODUCTION

• What is a MEMS (Micro Electro-Mechanical System)
  ?
• Miniaturization
• Components silicon, silicon-carbide
• Applications

- sensors - actuators - energetics micro-systems
SiC
Si
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What s MEMS ?
Accelerometer
a sensitive element
Actuator (switch)
frequently in silicon
packaging
Gear Miror
electronics
Pressure sensor
cea Leti
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But, it s also an energetics micro-system
Micron-scale counterflow heat exchanger
20 mm
Micro-turbine
MIT
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2 / APPLICATION TO MICRO-DRONES

• Mini and micro-drones
• fixed wing/rotating wing
• flapping wing
• Main specifications

Microbat Caltech
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Various MAV versions
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Microdrone specifications

• Flying binocular system for collection of
  proximity information
• Dimension up to 15 cm length and wingspan
• Hovering, flight at 50 km/h
• Autonomy 20 mn to 1h
• Power 20 to 50 W
• Mass ? 80 g
• Data transmission in real time

(Video or other)
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3 / Energetics micro-systems a lot of
micro-systems and actors

• Micro-turbine
• MIT, Tokyo, Hoseï, Sendaï University, Tokyo
  Metropolitan Institute of Technology, IHI, Onera,
  VKI, ERM, Leuwen University, National University
  of Singapore...
• Reciprocating free piston engine
• Georgia Tech, Berkeley, Birmingham University,
  KAIST (Corée)
• Wankel Micro-motor
• Berkeley, Birmingham University
• Thermoelectric micro-generator
• USC, Tohoku University, CEA, Onera, National
  University of Singapore
• Thermophotovoltaïc generator
• National University of Singapore, California
  State Polytechnic University ...
• Liquid rocket engine
• MIT, Uppsala University, QinetiQ, LAAS

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Reciprocating free-piston engine
stator of electric generator
Exhaust valve
Main shaft
piston
Inlet valve
Combustion chamber
Electrical leads
Single variation
KAIST Korea
1 mm thick glass Combustion chamber 1 mm Piston 2
x 2 mm
cea Leti
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Mini and micro-Wankel engine

• Presently 2.4 mm Si model
• Aim Si fabrication, 1 mm x 300 µm
• 10 to 100 mW
• SiC-coated Si

13 mm 3 W 10000 rpm
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Berkeley
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MIT Micro-turbine
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ONERA micro-turbine  upper combustor without
premixed channel 
hydrogene
Combustion chamber
exhaust
turbine
.,..
compressor
air inlet
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THERMOELECTRIC GENERATOR
Thermoelectric microgenerator
Thermoelectric wall
Combustion chamber
Hot Junction
Ceramic
Metallic Conductor
P
N
P
N
P
Semi conductor P or N
i

U
Cold junction
Ge-Si 3 W/cm² h ? 5
 Swiss roll 
USC
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Comparison between micro-systems

• Difficulties

• Advantages

• Reciprocating free piston engine
• rotating engine (Wankel)
• turbine engine
• thermoelectric system
• thermophotovoltaïque system

• Well known
• Well known
• Good conversion mecanic/electric
• Quasi static system
• Relatively simple System quasi static

• Heat losses, friction, low frequency
• Low rotating speed and low power
• Complexity, high rotating speed, journal bearing
• Connectic, catlytic combustion
• To control this technique

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4 / MICRO-TURBINE

• Thermodynamic cycle
• Energetic balance
• Small scales problems...
• Combustion/ignition

MIT
200 mm
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Thermodynamic cycle
C
Brayton-Joule cycle
hth 1 - 1/tc (g-1/g) tc 3 ? hth0.27 tc 4
? hth0.33 hc0.7 et ht0.6, thus h cycle ?
0.11 à 0.14
T
Ch comb
T
C
S
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MICRO-TURBINE ENERGETIC BALANCE
23 W
51 W
33 W
19 W
3 W
6 W
34 W
82 W

P comb 503 W
28 W
16 W
12 W
9 W
Net power 17 W Global efficiency 3,4
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COMPARISON OF PERFORMANCES
10000
Specific energy
Autonomy 1 h
20 mn
Wh/kg
1000
MICRO TURBINE
100

BATTERIES
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Specific power
SUPER CAPACITORS
W/Kg
1
1
10
100
1000
10000
100000
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Micro-scale combustorsSpecific problems

• 1/ Low Reynolds number (lt 1000)
• 2/ Residence time close to reaction time (Da
  around 1)
• 3/ Important heat losses (ratio S/V
  unfavourable)
• 4/ To improve ignition system (reusable)
• 5/ Quenching, self ignition in premixed channel

mixing
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Combustion mixing, residence time, quenching
fuel
Mixing fuel/air Mixing fresh gas/burned gas
air
Da residence time/ reaction time Da gt 1 ? ?c ?
0,5 ms, thus Vmin m.?c.r.T/P ? (4
mm)3 Quenching distance d// Pe.a/SL ? 0,2 mm
(H2) ? 0,7 mm (Propane)
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0D model results
PASR
PSR
Residence time in the micro-combustor
t s / t m
Heat losses
Mixing ratio
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ONERA s CFD code
Development tool in order to select the best
configurations of the micro-combustor
m 0,1 g/s P 3 bar Tp 950 K Model Ecklund
(7 reactions) Equi.ratio 0,6
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Set-up for combustion tests
Air and fuel inlet
Injection strut cooled,
air and fuel inlet
Micro-combustion chamber
Window for optical measurements
(IR caméra, Raman...)
Vessel
cooled by nitrogen
Exhaust
Combustion products
Micro-combustor
Vessel with micro-combustor
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5 / SUMMARY AND CONCLUSIONS
PhD work gt experimental study of mixing without
combustion 2004 and 2005 gt computations 0D
and 3D (for the design of the future
combustors) Combustion tests gt to carry out
ignition tests (hot wire or film, electrical
discharge) gt to assess the flame stability
(influence of heat losses, equivalence ratio,
type of fuel (hydrogen or hydrocarbon) ... gt to
evaluate the combustor efficiency (heat
balance, RAMAN scattering) Micro-systems gt to
study new concepts of micro-turbines and specific
combustors for direct electrical generation
(catalytic combustion)... gt thrust and journal
bearings Cooperations gt with other ONERAs
department for PLIF, RAMAN, thermoelectricity,
igniter, flow simulation inside
micro-compressor ... gt CEA (LITEN), INPG/LEG,
Silmach, NEDO (post doc.), TMIT ...
Manufacturing, mehanical/electrical conversion
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Micro-manufacturing
5 / MICRO-TECHNOLOGIES
Centrifugal Compressor
Si, Sic, Si3N4
Centripetal turbine
MIT
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GAS THRUST BEARING AND JOURNAL BEARING

• Rotating speed about 1 million rpm

MIT