The kinematics analysis on sway unit of LOX/Kerosene Rocket engine

Paper number

IAC-16,C4,IP,46,x34734

Author

Dr. Jian ZHAO, Xi'an Aerospace Propulsion Institute, China

Coauthor

Mr. Yonghua Tan, China

Coauthor

Prof. Chen Jianhua, Xi'an Aerospace Propulsion Institute, China

Coauthor

Mr. Song Yan, Xi'an Aerospace Propulsion Institute, China

Year

2016

Abstract

The large-thrust LOX/Kerosene rocket engine which is capable of swaying is the main power of China’s new generation Long March series of launch vehicles. With the help of the swinging engine, it is more simply and efficient for the rocket to control the flight directory by swinging the engine directly. The sway unit used as a flexible joint is the key assembly to achieve the swinging movement of engine.

The core component of sway unit is a tubular channel, which is referred as swinging hose. As the swinging hose is fitted in gimbal apparatus, the engine sways around the axis of gimble apparatus. For keeping uniform deformations and avoiding structural instability or failure caused by excessive local deformations of sway hose, it is necessary to coincide the symmetry axis of sway hose and gimbal apparatus, which is called ‘Best Assembly Relationships’. However, for achieving the demands of reasonable layout and compact structure, the swinging hose is not actually in ‘Best Assembly Relationships’. Consequently, it induces uneven deformations in swinging hose, which may weaken the strength, stiffness, and stability. So, it is a prerequisite job to obtain the motion features of swinging hose accurately for designing the overall layout of engine.

In order to acquire the deformations of swinging hose, a method to analyze different kinds of swaying movements is developed. Firstly, the movements of single swing DOF is analyzed, which shows that the swinging hose bends purely. When the angle between sway axis and installation axis is 45º, the swinging hose deforms uniformly and gets the minimum distortion angle which is about 70% of the swaying angle of engine. Secondly, the swing unit with two sway DOF are analyzed comparatively. For the case of two DOF and synchronous swinging, it can be treated as an equivalent motion of single swing DOF which is mentioned above. However, for the case of two swing DOF and asynchronous swinging, the engine sways alternately with different vertical pendulum swaying axis, the swinging hose deforms much more complex. Based on analysis of geometry and projection transformation, it is found that the torsional deformation is caused additionally, therefore, this case can be treated as syntheses motions of bending and twisting, the analytical methods for acquiring the twist angle are established as well.

Abstract document

IAC-16,C4,IP,46,x34734.brief.pdf

Manuscript document

IAC-16,C4,IP,46,x34734.pdf (🔒 authorized access only).

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