Masahiro Kanazaki
Tokyo Metropolitan University
Atthaphon Ariyarit
Tokyo Metropolitan University
Kazuhisa Chiba
Hokkaido Institute of Technology
Koki Kitagawa
Japan Aerospace Exploration Agency
Toru Shimada
Japan Aerospace Exploration Agency
Multi-objective Genetic Algorithm Applied to
Conceptual Design of Single-stage Rocket
Using Hybrid Propulsion System
The Eighth China-Japan-Korea Joint Symposium on Optimization of Structural and Mechanical Systems
○
May 25-29, 2014, Gyeongju, Korea

Background1 What is hybrid rocket engine?
2
Beneficial feature of HRE
・Low cost due to simple stricture
・Stop and restart of combustion⇒
Control・Safety
Hybrid Rocket Engine(HRE) ：
rocket which stores fuel and oxidizer by different phases.
Solid fuel + Liquid oxidizer :

3
Background2 Difference compared with existent rocket
 Solid rocket
 Liquid rocket
 HRE：Fuel and oxidizer are mixed after the ignition is initiated.
→ Fuel and oxidizer are preliminary mixd.
 Several parameter should be optimized for suitable
combustion → Design using heuristic approach
 Multi-combustion by the control of the oxidizer supplement
Solid fuel rocket
Liquid fuel rocket

Backgourng3 multi-combustion
 Stop/restart of combustion during total combustion time
Maximize down range by coasting
Minimization of maximum acceleration
Maximization of duration time over the target
altitude
4
Off
On On

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Contents
 Background
 What is hybrid rocket engine?
 Multi-combustion
 Objectives
 Design methods
 HRE design using evolutionary algorithm
 Formulation
 Maximization of altitude and minimization of gross weight(problem1)
 Minimization of maximum acceleration and minimization of gross
weight (problem2)
 Maximization of duration time over target altitude and minimization of
gross weight(problem3)
 Results and discussions
 Conclusions

Objective
Design exploration of launch vehicle
(LV) using HRE which can carried out
multi-combustion
Discussion of beneficial feature via several
design problem
Non-dominated solution by genetic algorithm (GA)
Comparison between HRE w/ multi-combustion
and w/o multi-combustion
6

Design method1/2
Overview of evaluation process of HRE
7
 tGatr n
oxiport )(
K., Kosugi, A. Oyama, K. Fujii, and M. Kanazaki.,
"Multidisciplinary and Multi-objective Design
Exploration Methodology for Conceptual Design of
a Hybrid Rocket," Infotech@aerospace2011, (2011)
AIAA 2011-1634

Design method2/2
Optimizer and visualization
 Non-dominated Sorting Genetic Algorithm-II
(NSGA-II)
20populations and 200generation
Parallel coordinate plot : PCP
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Evaluation of LV

Formulation1/3
Problem1
Maximization of maximum altitude (Altmax)/
minimization of gross weight(Mtot)
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Design variables for LV
Design variables for multi-combustion
L/D：Aspect
ratio of vehicle

Formulation2/3
Problem2
Minimization of maximum acceleration(accmax)/
minimization of gross weight(Mtot)
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MT-135
（JAXA’s rocket for weather observation（Altmax=60 km））
Alttarget：target altitude
Design variables for LV
Design variables for multi-combustion

Formulation3/3
Problem3
Maximization of duration time over Alttarget(Tduration)/
minimization of gross weight(Mtot)
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Design variables for LV
Design variables for multi-combustion

Result1/8 12
Non-dominated soluitions（Problem1）
Maximization of Altmax minimization Mtot
Similar result
Difference for high
altitude
50generations100generations150generations200generations

Result2/8
Design Space(problem1)
Similar trend in design space
Interval time of combustion dv8(tinter) is almost
zero. →Multi-combustion has not been required.
w/o multi-combustion w/ multi-combustion

Result3/8
Problem1
Multi-combustion is not effective
for maximization of Altmax
→ Altmax is only reduced by
the temporal stop of combustion.
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Result4/8
Non-dominated solutions（Problem2）
Minimization accmax and minimization Mtot
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accmax is reduced by
multi-combustion
50generations100generations150generations200generations

Result5/8
Design space(problem2)
Trend of dv4(tburn) is different between two cases.
Sorting by accmax，difference of dv5(Pc) could be
observed.
Due to multi-combustion，accmax could be reduced.
w/o multi-combustion w/ multi-combustion

Result6/8
Design space(problem2)
Colored by dv7(tstop) (w/ multi-combustion)
)
Correlation between
dv4(tburn)，dv8(tinter)

Result7/8
Problem2
Acceleration is stopped, when
the combustion is stopped.
Convergence of MOGA is not
good because it is difficult to
satisfy of the constraint
regarding the altitude.
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Result8/8
Non-dominated solutions（Problem４）
Maximization Tduration and minimization Mtot
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Difference is little.
200generations

Conclusions
Design exploration for the LV using HRE
which can carried out multi-combustion
Evaluation for HRE which can carried out multi-
combustion has been developed
Design problem evaluation by solving several
deign problems
Multi-combustion is not effective to maximize
the altitude/ the duration time.
Better solution could be obtained by the multi-
combustion in the minimization of maximum
acceleration.
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