August 5, 2014 (JST)

Japan Aerospace Exploration Agency

The Japan Aerospace Exploration Agency launched the S-310-43 sounding rocket from the Uchinoura Space Center on Aug. 04, 2014, with the objective of "measuring two-phase flow behavior (*1) and heat transfer characteristics during coasting flight". The experiment was conducted successful.

The S-310-43 dropped into the south eastern ocean off Uchinoura after its normal flight and operation of onboard equipment.

In the present experiment, by using the sounding rocket's sub-orbital ballistic flight, similar environment to that on liquid-fueled rockets during the coasting flight on orbit was realized. Under the low-gravity state, the cryogenic test fluid, liquid nitrogen, was introduced into the test sections of similar shapes to the flow channels in the cryogenic propulsion systems. The boiling of liquid nitrogen inside the test-sections and the transition of flow regimes from gas/liquid two-phase flow to liquid mono-phase flow were visualized. The temperatures, pressures and void fractions of each channels were measured as well.

During this experiment, liquid nitrogen reached at the test section (*2) at about 100 seconds after liftoff, and data for temperatures, pressures and void fractions (*3) as well as image data of two-phase flow behavior in the test sections were acquired.

Further analysis will be performed by utilizing acquired data to improve the accuracy of thermal fluid analysis models for cryogenic propulsion systems.
The rocket was tracked by an optical camera till 33 seconds after liftoff.
Today’s weather at the time of the launch was cloudy, the wind speed was 3 meters/second, and the temperature was 26 degrees Celsius.
We would like to express our profound appreciation to all related parties and personnel who have been cooperating with the launch of the S-310-43 sounding rocket this time.

(Note)

• (*1) Two-phase flow behavior: Mixed condition of gas and liquid. During the experiment this time, cryogenic liquid (liquid nitrogen) flowed into the specimen to measure its boiling and flowing conditions to improve the accuracy of a thermal fluid analysis model.
• (*2) Specimen: an experiment instrument which simulates a cryogenic propulsion system.
• (*3) Void fraction: the area ratio of bubbles per unit cross-sectional area in liquid