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Numerical Simulation Technology

Numerical Simulation Technology

Numerical simulation technology has been the third major method, after conventional methods theory (including rule of thumb) and experiment, and is indispensable for modern research, designing and development. On the other hand, numerical simulation technology is still at a developmental stage worldwide in the space development field, as it entails physical phenomenon under the extreme environment, such as high pressure, very low temperature, microgravity and high vacuum related to rockets and spacecraft. In order to solve technology challenges on rockets and spacecraft and to contribute to designing and development innovation, research Unit III has been conducting research and development in cooperation with domestic and overseas relevant organizations, aiming to acquire the world’s top level numerical simulation technology in the concerned field. The unit has also been supporting to solve technical challenges by applying acquired technologies to a variety of JAXA missions and research activities.

Outline of Numerical Simulaion Technology DevelopmentResearch and Development Activities of Numerical Simulation Technology

Research and Development of Numerical Simulation Technology on Rockets and Spacecrafts

Research and Development of Numerical Simulation Technology on Rockets and SpacecraftAdvantages of Numerical Simulation

1. Internal Flow/Combustion/Turbomachinery Simulation Technology

We have been proceeding with research and development on analysis technology related to internal flow, combustion and rotatory machine, which are base elements for carrying out reduction of risks, including unreached capacity and malfunction, in the designing and development of rocket engines and spacecraft thrusters. Currently, we are proceeding with research and development on analysis technology which can predict thrust performance, cooling performance, life span and the largest risk combustion instability in a quantitative manner, targeting the most important component combustor.
We have achieved reproduction of physical phenomenon on combustion instability that developed in a sub-scale combustor, quantitative prediction of cooling characteristics in a full-scale combustor and elucidation of the mechanism of creep-fatigue damage phenomenon and such.
The technology has been utilized for designing assessment on the first and second stage engines of the new flagship rocket, H3 which designing and development has started since 2014.

Internal Flow/Combustion/Turbomachinery Analysis TechnologyNumerical Simulation Technologies for Liquid Rocket Engines

2. Acoustic Simulation Technology

Acoustic Analysis Results of Epsilon Rocket upon Liftoff
(Fluid Field: Mach Number, Acoustic Field: Static Pressure) Acoustic Analysis Results of Epsilon Rocket upon Liftoff
(Fluid Field: Mach Number, Acoustic Field: Static Pressure)

We are researching and developing technologies to analyze/predict extremely loud acoustic environments that are generated upon rocket lift-off and transonic flight.
We analyze fluid phenomenon that are acoustic generation mechanism with CFD, and the process from the transmission through a fairing structure to the on-loaded satellite with vibro-acoustic FEM.
In the past, we applied CFD technology that analyze acoustic generation mechanism for designing Epsilon rocket launch sites and achieved the acoustic level of the on-loaded satellite to be 1/10 of that of M-V rocket. The low noise level was outstanding in the world among the small and medium sized rockets, and the cost for maintaining launch sites was realized with 1/10 of that of the conventional methods. Currently, we are applying the technology into the new flagship rocket H3.

3. Rarefied Gas Dynamics Simulation Technology

H-IIBロケット上段再突入評価 天文衛星SPICAプルームコンタミ評価 HTVメインエンジンプルーム影響評価
Top (L) H-IIB Rocket Upper Stage Re-entry Assessment (R) Astronomical Satellite SPICA Plume Contamination Assessment
(Bottom) HTV Main Engine Plume Affect Assessment

We are researching and developing analysis technologies to implement risk assessments on dilute fluid peculiar to outer space, related to various space development missions, such as space transportation, manned space, scientific research satellite and planetary exploration. Specifically, we are developing analytical technology that enables aerodynamic/thermal environmental prediction in atmosphere entry, thermal/pressure load prediction with exhaust gas plume in outer space and outgas distribution prediction from structural materials.
This analysis technology has been utilized for assessing thermal/pressure load of the gas plume, which is exhausted from the main engine thrusters of “H-II Transfer Vehicle” (HTV), on the International Space Station (ISS)

4. Propellants management Simulation Technology

H-IIAupgarade_tank Computed Results of Liquid Propellant Behavior under a Microgravity Condition

We are proceeding with research and development on analysis technology that can predict thermo-fluid dynamics inside the piping of the propellant tank and engine quantitatively in order to reduce risks, including unreached capacity and malfunction, in designing and developing rockets and spacecraft propulsion system.
Specifically, the execution of predicting “chill-down process of turbo pump” and “propellant distillation inside the tank on in-flight rocket” enables quantitative assessment of rocket throttling, and is utilized for designing and developing the flagship rocket’s propulsion system.

5. Safety Assessment Technology Using Numerical Simulation

We are developing quantitative safety assessment technology (QSA), using high-fidelity simulation for the purpose of making safety requirements on rockets and spacecraft stricter and strengthening global competitiveness on performance and operability.
We are developing simulation technology that can specially handle various hazard events and efficient stochastic assessment technology.
We are also utilizing these for assessing on areas of debris falling and dispersing upon re-entry of HTV and H-IIA/B upper stage, as well as for assessing flight safety of rockets, and for designing parachute emission system of small recovery capsules.

High-fidelity Hazard Simulation Outline of Safety Assessment Technology Using Simulation

6. Physical and Mathematical Modeling for Rockets and Spacecrafts

In order to realize future JAXA missions, physical and mathematical models that are essential for numerical simulations of rockets and spacecrafts (above mentioned No. 1 to 5) have been developed in “the rocket and spacecraft modeling laboratory” established in the University of Tokyo under the collaboration between the university and JAXA. The laboratory is located in the University of Tokyo and is conducting research activities based on the ALL-JAPAN research community including universities, industries, and national research institutes in all over Japan. In the current laboratory, the following four research topics are now underway:

 I.   Quantitative Safety Analysis by High-fidelity Simulations
 II.  Reactive thermal-fluid dynamics
 III. Propellant thermal-fluid dynamics
 IV.  Contact/friction phenomenon

In those research activities, we are aiming to make Japan’s numerical simulation technology of rockets and spacecrafts the world top level and make breakthroughs to realize future innovative missions.

Construction of Rocket/Spacecraft Physical Mathematics Model Research Activities of Physical and Mathematical Modeling for Rocket and Spacecraft

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