P02
小型超音速飛行実験機燃料タンク向け加圧ガス巻きこみ抑制技術に関する研究（スロッシング抑制技術の開発）
Study on Pressurized Gas Entrainment Suppression
Technology for Small-scale Supersonic FlightExperiment Aircraft Fuel Tanks(Development of Sloshing Suppression Technology)
和田拓也 1, 眞鍋美羽 1, 藤田宥磨 1, 今井良二 1，中田大将 1，高野智之 1，内海政春 1
Takuya WADA1, Miu MANABE1, Yuma FUJITA1, Ryoji IMAI1, Daisuke NAKATA1, Tomoyuki
TAKANO1, Masaharu UCHIUMI1
1

室蘭工業大学，Muroran Institute of Technology

1. Introduction
The Aerospace Plane Research Center in Muroran Institute of Technology is development the small-scale
supersonic flight experiment aircraft as a flying test bed for a technical demonstration in high-speed flightenvironment. In the small-scale supersonic flight experiment aircraft, the liquid supplying system forbioethanol (BE) and liquid oxygen (LOX) by nitrogen pressurant has been studied. However, sloshing in
expected to occur in this liquid fuel tank by the acceleration during flight. It is feared that the risk of adverse
effects on the attitude control of the aircraft and the propulsion system by the inclusion of pressurized gas in
the supplied fuel increase due to sloshing.
The purpose of this paper is to research and develop a sloshing suppression device in the aircraft fuel tankand evaluate its performance.
2.

The sloshing suppression device
Figure 1 shows a structure of the sloshing suppression device. Cylindrical geometry is used for thestructure of the sloshing suppression device. By using a cylindrical geometry in the structure of the
suppression mechanism, damping due to viscous stress increases outside the cylindrical geometry due to theincreased contact area between the liquid fuel and the solid wall. Inside the cylindrical geometry, the ringbaffle concept, which is a common method of suppressing transverse sloshing 1), is applied to suppress it.
Sloshing can be controlled both inside and outside the cylindrical shape, reducing sloshing throughout the1 of 8

tank.
The use of metal mesh on the cylindrical side walls prevents sloshing while preventing liquid
accumulation inside the mechanism. This is because the surface tension of the liquid forms a liquid film on themetal mesh, which can be regarded as a pseudo solid wall.

Figure 1. Installation of the sloshing suppression device.

3.

Experimental Method
To compare the liquid behavior of the newly designed sloshing suppression device when the entire

experimental setup, including the full-scale model tank, is subjected to instantaneous acceleration in the pitch
direction using a crane to evaluate the performance of the device. The liquid to be observed is water coloured
with food colouring, and the liquid volume is 80%, 50% and 20%, with 80% of the liquid remaining
immediately after the start of liquid discharge, 50% when the liquid level drops to the center of the tank and20% when the liquid level is near the end of discharge. A new cylindrical suppression device and a disc-shaped
suppression device were developed for the suppression device mounted inside the tank, and a performancecomparison was carried out between a case with and without these two suppression devices. The structuresof the cylindrical and disc-shaped suppression devices are shown in Figures 2 and 3 respectively. Figure 4
shows the appearance of the fabricated experimental apparatus.

2 of 8Figure 2. The structure of the cylindricalFigure 3. The structure of the disk-shaped

suppression device.

suppression device.

Figure 4. Experimental apparatus with full-scale model tank.

4.

Experimental result and discussion
Table 1 shows the vibration test results. In Number 1 (20% liquid volume, 0.40 sec after the start of drop),

the liquid did not behave in a splashing manner as in the case of the disk-shaped suppression device in the3 of 8

case of the cylindrical suppression device and in the case of no suppression device, and it can be said thatsloshing was suppressed. In Number 2 (20% liquid volume, 1.47 sec after the start of the drop), sloshing wassuppressed by the cylindrical suppression device because the turbulence of the liquid surface was small, as in
the case of the disk-shaped suppression device and the case of no suppression device.

Table 1. Image of the results of vibration tests on full-scale model tank.

NumberDevice

1220% liquid volume, 0.40 sec after the20% liquid volume, 1.47 sec after thestart of drop

start of drop

The cylindrical sloshing
suppression device

The disk-shaped sloshing
suppression device

Without sloshing
suppression device

Figures 5, 6 and 7 show the time variation of the liquid level height at the right end of the cylindrical part ofthe model tank at 50% liquid volume when a cylindrical suppression device is installed, when a disc-shaped
suppression device is installed and when no suppression device is installed, respectively. The liquid level
height was recorded using the image processing software ImageJ2).

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Height [mm]

340
330
320
310
300
290
280
270
260
250
02468101214161820

Time [sec]Figure 5. The change in liquid level height when the cylindrical suppression device

Height [mm]is in place at 50% liquid volume.

370
360
350
340
330
320
310
300
290
280
02468101214161820

Time [sec]Figure 6. The change in liquid level height when the disk-shaped suppression device

Height [mm]is in place at 50% liquid volume.

320310300290280270260250240
230
02468101214161820

Time [sec]Figure 7. The change in liquid level height when no suppression device
is in place at 50% liquid volume.
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The results show that a cylindrical suppression device has a higher damping effect than a no suppression
device. A comparison between the cylindrical suppression device and the disc-shaped suppression deviceshows that there is no significant difference in the damping effect between the two. Table 2 summarizes theresults of the experiments so far.

Table 2. Summary of experimental results in full-scale model tank.

DeviceEffectiveness in reducing
liquid level behavior.

Attenuation effect.

The cylindrical suppression device〇〇

The disk-shaped suppression device〇

×

Without suppression device×〇

Based on the above results, it is considered that the cylindrical shape is a promising shape for a sloshing
suppression mechanism, judging from the overall suppression and damping effects of changes in the liquidlevel behavior of the liquid in the tank.

5.

Optimization of the sloshing suppression device
Prior to the structural optimization of the sloshing suppression device using computational fluid dynamics(CFD) analysis in three dimensions, a three-dimensional analysis of the flow behavior without the sloshing
suppression device is analyzed. Acceleration data measured at the High-Speed Test Track at the Shiraoi Engine
Test Field of the Muroran Institute of Technology are introduced to predict the fluid behavior undercontinuous acceleration by analysis. Table 3 shows a comparison between the actual video footage and theanalysis results. As shown in the above results, the prediction of flow behavior during acceleration wasreasonable.

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Table 3. Comparison of filmed images and analysis results.

Elapsed timesince start ofFilmed image.

Analytical results.

acceleration.

0.23 sec

0.5 sec

2 sec

6.

Conclusion
In this study, a sloshing suppression device mounted inside the fuel tank of a small-scale supersonic flight

experiment aircraft was developed to develop a fuel sloshing suppression technology. A cylindricalsuppression device was devised and tested, and the suppression effect was investigated by comparing theliquid behavior between the case without a suppression device and the case with a disc-shaped suppression
device by means of vibration tests. As a result, it was confirmed that the change in the behavior of the liquid
was slower when a cylindrical suppression device was installed than when no suppression device wasinstalled or when a disc-shaped suppression device was installed. It was also confirmed that the cylindrical
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suppression device had a higher damping effect than the case without the suppression device, and the samelevel of damping effect as the disc-shaped suppression device. Based on the above results and judging fromthe overall suppression of changes in liquid behavior and the damping effect, the cylindrical-shaped
suppression device is considered to be promising as a sloshing suppression technology. CFD analysis in three
dimensions was used to predict the fluid behavior during acceleration when the suppression device is notinstalled.
In the future, it is necessary to establish a technique for predicting flow behavior during deceleration when
the suppression device is not mounted, to evaluate the performance of the cylindrical suppression device usinga High-Speed Test Track and to optimize the geometry using CFD analysis.

Reference
1) Keiji KOMATSU, Sloshing Liquid level fluctuations and tank vibrations, 1st ed., Morikita Publishing Co., Ltd.
(2015)
2) https://fiji.sc/ (referenced on September 1st)© 2023 by the authors. Submitted for possible open access publication under theterms and conditions of the Creative Commons Attribution (CC BY) license(http://creativecommons.org/li censes/by/4.0/).

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