Effect of Channel Rotation on Premixed Turbulent Combustion in a Wave Rotor Combustor

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22 Φεβ 2014 (πριν από 3 χρόνια και 7 μήνες)

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Injector nozzle

Combustion:

eddy
-
diffusion model with
finite
-
rate chemistry and a single
-
step global reaction mechanism:

Effect of Channel Rotation on Premixed Turbulent Combustion
in a Wave Rotor Combustor


AIAA Paper 2007
-
5053, 43rd Joint Propulsion Conference, Cincinnati, OH

Viktor
Kilchyk
,
Razi

Nalim
, & Charles
Merkle

Introduction.
Flame speed drives design of a wave rotor combustor (WRC). Flame acceleration by weak shock waves and pressure waves under
buoyancy conditions due to rotation is studied at conditions close to those expected in a WRC test rig under construction.

Numerical Approach

Channel geometry. Dimensions are shown in meters

Code:

Fluent 6.3, coupled solver,
k
-

ε

turbulence model
with enhanced wall
treatment

Grid
: 86,335 nodes, 0.25
-
2.7mm
resolution

Boundaries:

viscous adiabatic
walls and pressure inlet

Rotation:

4000 rpm, 0.23m
radius, centrifugal
acceleration ~4,000 G

Jet ignition:

stoichiometric
products of C
3
H
8

combustion at 2200K
and 0.202 MPa total
inlet pressure; open for
0.75msec

Time = 0.001s

Time = 0.003s

Time = 0.004s

Time = 0.005s

Time = 0.006s

Time = 0.007s

Time = 0.008s

Time = 0.009s

Time = 0.002s

Comparison of the temperature (K) history in the non
-
rotating (left) and rotating (right) channels

0
2
4
6
8
10
12
14
0
2
4
6
8
10
Time, milliseconds
Reaction rate,
(kgmole/s/m)
no rotation, centered jet
rotation, centered jet
rotation, jet at a smaller radius
rotation, jet at a larger radius
0
10
20
30
40
50
60
0
2
4
6
8
10
Time, milliseconds
Reacted fuel,
(kgmole/m)
no rotation, centered jet
rotation, centered jet
rotation, jet at a smaller radius
rotation, jet at a larger radius

Rate of reaction and reacted fuel in non
-
rotating and rotating channels with different nozzle position

Case studies:


Flame propagation in the non
-
rotating
channel


Flame propagation in the rotating channel


Flame propagation in the rotating channel
with off
-
centered ignition nozzle position


Main Conclusions


The effect of rotation on the overall fuel
consumption rate has been studied in the
rotating channel under the conditions
close to design conditions in the WRC rig
at Purdue University.


It was found that the effect of rotation on
the overall fuel consumption rate is minor
when ignition is provided with a hot gas jet
(∆P
shock

= 101kPa vs. ∆P

rotation
= 3.7kPa).


Gas motion produced during ignition,
along with shock waves, had a stronger
impact of the flame dynamics than
buoyancy forces.


The main increase in the overall reactions
rate came as a result of flame
-
shock
interactions.


Employing a nozzle position closer to the
inner or outer wall resulted in less jet
penetration into the channel, larger flame
surface area and the creation of large
vortex structures at the early stages of
flame propagation.

3 8 2 2 2 2 2
5( 3.76 ) 3 4 18.8
C H O N CO H O N
Comparison of the transient flow field in the non
-
rotating (upper) and rotating (lower) channels at 0.003s after jet injection

Velocity, m/s