別紙41 (課程博士(英文))Date ofsubmission (month day, year)

Depar[ment ofStud引ltlD Number

MechanicalEngineerin容Pplicant's name

D153198
Supervis0玲

January.4小.2022

YujiNakamura
HidekiYanada

Akiyoshilida

DaikiMatsugi

Abstract (Doctor)
Title ofThesis

Study ofBurning characteristics ofa porous combustible soaked in a Liquid
Oxidizer

Approx.80o words
Xvith an increasino trend in development of smaⅡer sateⅡites o、Ni11g to significant pl'ogress in
microelectronics, and together with an increasing a、 ,areness of thl'eats to the environment, a
dedicated smaⅡ launch vehicle for launching the sma11er sateⅡites, employinσ elwironmenta11y
friendly propeⅡant are becoming highly demanded. To respond this, a hybrid rockets have been
御'omising for the launch vehicle and of great interest by many reseal'ch groups. Although great efforts
have been made ever,its practical application as the launch vehicle has be引l found to be cha11enging.
In 1997, Na8ata et al. proposed a simple prope11ant consisting of a porous combustible soaked in aIiquid oxidizer. They lnade an experimental hlvestigation of pressure dependency on regression rate
Of the propeⅡant, and it 、Nas found ulat the prope11ant could achieve exce11ent thrusting performance
Comparable to the existing chemical rocket systems. on the other hand, un、Nanted buming behaviors,
Such as an explosion・1ike buming,、Nere frequently observed in their experiments, and data scattering
Of the regression rate 、Nas lneasured at random pressure hltheil" experiments.1n addition, the burning
Characteristics have been limited to the pressure dependency on the regression rate since 1997. Forguaranteeing safety and reliability of the prope11ant 、Nhile leveraging its exce11ent thrustil)gPerformance, it is necessary to obtain comprehensive kno、Nledge of the fundalnental burning
Characteristics of the propeⅡant and clarify the reason for the un、Nanted burning and the data
Scattering as fundam引)tal research.1n ulis 、へ10rk, as referred to t11e previous work by Nagata et al.,Comprehensive experim引ltal and numericalinvestigations on the fundamental burning characteristics
Ofthe propeⅡant 、¥ere conducted
Comprehensive experimentalinvestigations to obtain the fundamental bunling characteristics of theSpecimen, consisting of a polyethylene foam soaked in enl'iched hydrogen peroxide, were conducted.
10 examine the fundamental burning characteristics, such as bunling behavior, regression rate, its
Steadiness, thermal structure during entire burning event, and one‑dimensionality of burning process,an experimental setup, testing method010gy, and a simple thermal analysis 、vere introduced.
Experiments in nitrogen・fiⅡed environment 圦ノ引'e carried out at various presSⅢ'es (0.1 Mpa ‑035Mpa) and fuel porosities (0.6 ‑0.9) to obtain those of the fundamental burning characteristics.1t 、Nas
found that an end・bunling at 、Nhich top S11rface (bun〕ing surface) ofthe specimen moves down、¥ard at
reasonably constant rate is successfU11y achieved under the conditions studied in this 、N,ork. From
results of t11e direct observation during the burning event and direct temperature measurements bythermocouple, it 、Nas revealed that progress of the tested specimen shaⅡ be dominated by thePremixed・1ike surface aame established in the vicinity ofthe top surface. Furthermore, it 、Nas provedthat the one・dimensionality of the bunling process shaⅡ be vaHd by the simple thermal analysis.
These facts helped to develop a simple burning model under assumptions; the steady state, premixed
Combustion, and one・dimensionality.
Based on the experimenta11y obtained facts, a simple one・dimensional burning model 、Nas thendeveloped to numerica11y investigate t11e fundamental burning characteristics.1he thermal structure
and the potential regression rate under various prescribed conditions were predicted using the burningmodel developed in t11is 、刃ork. separately considering the estimated blo、N・off limit in the gas・phase
Over dle top surface by cHEMKIN (PREMI×・code), a range needed to achieve successive burning、Nas numerica11y predicted. The effects of oxidizer type (hydrogen peroxide and liquid oxygen), thefuel porosity, and pressure on the potentia11、e即'ession rate, the thermal structure, and blo、¥、off limit、Nere then discussed. Findings show dlat tl〕e successive burning is widely achievable 、Nhen hydrogen
Peroxide is used as t11e liquid oxidizer, but it is only partia11y aC11ievable 、Nhen liquid oxygen isUtilized. This fact may support the data scattering and the behavior observed in the previous 、Norkreported by Nagata et al.

Product gases of tl)e bunling specimen at nitrogen・balanced o.1 Mpa ambient to predict thrusting
Performance of the present specilnen 、Nere studied. 1n the experiments, we first measured

One・dimensional (1・D) C02 and H20 concentration profiles over the regression surface by a gas
Chromatography under various fuel porosities o.フフ‑0.84. The concentration profiles exhibited nearly"at, suggesting t11at chemical equilibrium 、Nas reached satisfactory immediately after t11e regression
Surface. The equilibrium calculation 、Nas then utilized in order to w'edict optimal combination ofPyrolysis gases, oxidizer gases, and their mass fraction, and estimate t11e ot11er product gases
PotentiaⅡy produced and thrusting perfonnance achievable in this b11rnino specimen. T、No important
facts 、Nere noted:(D the predicted mass fraction of oxygen shaⅡ be lower than that of pure H202 and(2) major pyrolysis gases components were found to be methane (CHO, ethylene (C?HO, and edlane(C2H6). Expected specific ilnpulse potentia11y achievable by d〕e present burning specimen 、Nasestimated and found to be in the range of 95 S t0106 S, depending on the initial concentration of H202.
This fact implied that using pure H202 、Nas preferred to achieve the larσer specific impulse of thePresent speclmen.