study and development of throttleable hybrid rocket motors · valve in hybrid rocket motors was...
TRANSCRIPT
Study and Development ofThrottleable Hybrid Rocket Motors
Alessandro Ruffin
University of PadovaCentro di Ateneo degli Studi e Attivita Spaziali ”Giuseppe Colombo”
September 22nd 2017
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 1 / 14
Throttleable Hybrid Rocket Motors
Nammo test, Spartan Project
Applications
Launchers
ADV
Flying test beds
For a fixed nozzle throat, throttleability isachieved by controlling the oxidizer flow ⇒Flow control valve (FCV)
Advantages
Increase trajectory efficency
Peculiar mission profiles requiring deepthrottling
Requires to control a single feeding line
Disadvantages
Increase system complexity
o/f shifting
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 2 / 14
C ? Penalties
Circular port
Port fuel consumpion
Marxman power law
o/f =m1−n
ox Dport2n−1
4n π1−n a ρf L
n = 0.5 ⇒ no Dport sensitivity
n = 1 ⇒ no mox sensitivity
n ∈ [0.45 0.8]
2 4 6 8 10 12 14 16 18 20 22
o/f []
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
Cha
ract
eris
tic v
eloc
ity [m
/s]
HTPN
2O
LOX
90%HTP N2O LOX
Maximum c∗ [m/s] 1598 1559 1773
c∗ Sensitivity [m/s] −22.4 −16.3 −369.9
c∗ Penalty TR=5 (balanced) 95.3% 95.9% 96.2%
c∗ Penalty TR=5 (fuel rich) 88.0% 84.5% 82.7%
c∗ Penalty TR=10 (balanced) 91.6% 92.8% 93.2%
c∗ Penalty TR=10 (fuel rich) 78.3% 78.5% 75.4%
Arbitrary throttling ⇒ o/f shift ⇒ Performance reduction
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 3 / 14
FCV selection
Techniques:
Pure dissipative valve
Variable area injection
Parallel feeding lines
Variable area cavitatingventuri
For a CV:
mox = Cd Ath
√2 ρox (p◦ − psat)
Peculiarities
variable area ⇒ flow control
if p◦up > [0.8 0.9] p◦down ⇒ tank -combustion chamber uncoupling
41 42 43 44 45 46
Time [s]
5
10
15
20
25
Pre
ssur
e [b
ar]
cat postcc
tank ox
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 4 / 14
This year:
Flow control valve design concluded
Integration and testing
Flow control valve characterization
Static hybrid rocket motor fire tests
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 5 / 14
FCV: Design
A
A
Step DC Motor EncoderFCV
VALVE ACTUATION
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 6 / 14
FCV: Design
Minimum mass flow range 30 [g/s]
Maximum mass flow range 300 [g/s]
Maximum operating pressure 80 [bar ]
Venturi throat diameter 2.2 [mm]
Upstream throat radius 3.3 [mm]
Venturi divergence angle 10 [deg ]
Pintle apex angle 10 [deg ]
Maximum pintle stroke 11 [mm]
Useful pintle stroke 7 [mm]
Features
Conical pintle/spike
Manually moved pintle
Pressure tap for feedback
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 7 / 14
FCV characterization: Set-up
N2 tank
PR1 PR2 V05
x
Vtes t
Vc
Vdump Vpurg e
Vtank
VACV
HTP tank
To collector
To collector
Low pressure N2
Pup PdownPtank
Features
HTP tank (piston separator)
Flow control valve
Catalytic bed (not shown)
Test motor (not shown)
Purging line
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 8 / 14
FCV characterization: Results
H2O
1 2 3 4 5 6 7 8 9 10
Pintle stroke [mm]
0
50
100
150
200
250
300
350
400
Mea
sure
d m
ass
flow
[g/s
]
30 bar45 bar60 bar
91 % HTP
1 2 3 4 5 6 7 8 9 10
Pintle stroke [mm]
0
50
100
150
200
250
300
350
400
450
500
Mea
sure
d m
ass
flow
[g/s
]
30 bar45 bar60 bar
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 9 / 14
FCV characterization: Results
H2O
1 2 3 4 5 6 7 8 9 10
Pintle stroke [mm]
0.9
0.91
0.92
0.93
0.94
0.95
0.96
0.97
0.98
0.99
1
Dis
char
ge c
oeffi
cien
t []
30 bar45 bar60 barfit
91 % HTP
1 2 3 4 5 6 7 8 9 10
Pintle stroke [mm]
0.9
0.91
0.92
0.93
0.94
0.95
0.96
0.97
0.98
0.99
1
Dis
char
ge c
oeffi
cien
t []
30 bar45 bar60 barfit
CD,H20 = 1.008− 2.626 x − 93.14 x2 − 4.643 · 10−5/x , R2 = 0.93
CD,HTP = 1.003− 0.7345 x − 174.5 x2 − 3.086 · 10−5/x , R2 = 0.86
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 10 / 14
Test Motor: Fire test campaign
A test campaign was conducted to characterize the test motor behaviorwith different mass flows. Tests were conducted in the fuel rich region.
10 12 14 16 18 20 22 24 26 28 30
Time [s]
0
5
10
15
20
25
30
Pre
ssur
e [b
ar]
post catalytic
combustion chamber
Test # mHTP tb pcc[g/s] [s] [bar]
1 56.5 25 8.62 137.9 16 20.93 219.0 7 33.14 282.1 5 43.5
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 11 / 14
Test Motor: Fire test campaign
A test campaign was conducted to characterize the test motor behaviorwith different mass flows. Tests were conducted in the fuel rich region.
50 100 150 200 250 300
Oxidizer mass flow [g/s]
5
10
15
20
25
30
35
40
45
Com
bust
ion
cham
ber
pres
sure
[bar
]
Test # mHTP tb pcc[g/s] [s] [bar]
1 56.5 25 8.62 137.9 16 20.93 219.0 7 33.14 282.1 5 43.5
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 12 / 14
Conclusion and Future work
A variable area cavitating venturi to be used as flow controlvalve in hybrid rocket motors was developed and characterized
Our test motor was tested with four different oxidizer massflows reaching a 1:5 throttling ratio
Automatically control the pintle stroke implementing a DCmotor
Characterize the dynamic behavior of flow control valve andtest motor
Throttling tests
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 13 / 14
Conclusion
Thank you! Any question?
Alessandro Ruffin Throttleable Hybrid Rocket Motors September 22nd 2017 14 / 14