著者

渡邉 力夫 林 浩平 岩尾 正樹 井河 恵大 冨田 信之

出版者

一般社団法人 日本航空宇宙学会

雑誌

宇宙技術 (ISSN:13473832)

巻号頁・発行日

vol.7, pp.45-52, 2008 (Released:2008-10-11)

参考文献数

9

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When liquid nitrogen and heated water are mixed in a chamber, pressure increase due to evaporation expansion inside the chamber becomes high enough to generate thrust force for rocket propulsion. This thrust system is safer and environment-friendly compared to conventional rocket engines utilizing combustion process. This new type of rocket engine system is called "Water-Liquid Nitrogen rocket engine system" and it can be used for small payload mission with expected altitude of several kilometers. In this paper, experimentally obtained thrust characteristics are shown and analyzed. As a result, relations between the thrust force and the mixing chamber pressure are clarified. Also, it is found that the present injector can attain only half of the theoretically expected specific impulse due to insufficient mixing efficiency.

著者

渡辺 力夫 冨田 信之 竹前 俊昭

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.51, no.593, pp.314-320, 2003 (Released:2003-09-26)

参考文献数

17

被引用文献数

2 2

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The propulsive characteristics of water rockets are analyzed theoretically and experimentally. The unsteady thrust force acting on a PET bottle and the air pressure inside the bottle are measured simultaneously by the thrust test stand we have developed. The semi-empirical thrust history is obtained utilizing the air pressure history and it is compared with the measured thrust history. The results show qualitative agreement. The observation of the flow inside bottle by a high-speed video camera shows that the air precedes water when it is about to be discharged entirely. We have developed a flow regulator attached to the nozzle cap to reduce the precursor air discharge that is considered as a result of the swirling flow inside the bottle. The experimental results show that the air discharge and the body vibration are suppressed effectively.

著者

冨田 信之

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. C編 (ISSN:03875024)

巻号頁・発行日

vol.61, no.583, pp.922-929, 1995-03-25

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When a rocket is launched by a rail launcher, the rocket receives tip-off angular velocity caused by the moment due to engagement of the tail hanger of the rocket on the rail after clearance of rocket C.G. from the tip of the rail. This paper analyses one occasion, when small test rocket launched from a rail launcher experienced unexpected large pitch-down tip-off angular velocity. The rocket had two hangers, one of which was constrained by a detent mechanism prior to launch. When the rocket motor was fired, detent action caused torsional deflection of the shaft, which supported teh rail launcher. When the hangers got free, the shaft started oscillatory motion, which amplified the tip-off angular velocity of the rocket. Analysis of the dynamics of the rail launcher and the rocket was performed and numerical calculation was made to simulate the tip-off velocity. Measures for improvement were summarized.

著者

渡辺 力夫 冨田 信之 竹前 俊昭

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.52, no.609, pp.449-455, 2004 (Released:2004-11-30)

参考文献数

12

被引用文献数

1

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The aerodynamic characteristics of water rockets are analyzed experimentally by wind tunnel testing. Aerodynamic devices such as vortex generators and dimples are tested and their effectiveness to the flight performance of water rocket is discussed. Attaching vortex generators suppresses the unsteady body fluttering. Dimpling the nose reduces the drag coefficient in high angles of attack. Robust design approach is applied to water rocket design for flight stability and optimum water rocket configuration is determined. Semi-sphere nose is found to be effective for flight stability and it is desirable for the safety of landing point. Stiffed fin attachment is required for fins to work properly as aerodynamic device and it enhances the flight stability of water rockets.

著者

小井沼 久哉 渡邉 力夫 竹前 俊昭 冨田 信之

出版者

一般社団法人日本機械学会

雑誌

年次大会講演論文集 : JSME annual meeting

巻号頁・発行日

vol.2000, no.4, pp.527-528, 2000-07-31

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Sloshing motion inside of tank of water rocket has a significant influence on the flight characteristics of the rocket Sloshing characteristics of water rocket was studied on the ground test and its influence on the flight was observed by the flight test. It was identified that rocket with conventional nozzle has large sloshing motion inside of the tank and its flight was unstable. On the other hand, rocket with newly developed nozzle has small sloshing motion and its flight was quite stable.

著者

渡辺 力夫 橋村 一正 冨田 信之 竹前 俊昭

出版者

一般社団法人日本機械学会

雑誌

年次大会講演論文集 : JSME annual meeting

巻号頁・発行日

vol.2000, no.4, pp.525-526, 2000-07-31

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The propulsive characteristics of water rockets have been analyzed experimentally by the thrust test stand. It can measure the unsteady thrust force acting on a PET bottle and the air pressure inside the bottle simultaneously. The result of the observation by a video camera shows that air precedes water when it is about to be discharged entirely, and the measured thrust history indicates that it decreases suddenly then. We have developed a flow regulator to reduce the precursor air discharge which is considered as a result of the swirling flow inside the bottle. The experimental results show that the air discharge is suppressed and the thrust history is improved to have a potential for higher altitude.