Study on the Simulation Technique of the Virtual Vibration Test for Liquid Rocket Engine

Paper number

IAC-11,C4,3,14,x10395

Author

Mr. DENG Changhua, Xi'an Aerospace Propulsion Institute, China

Coauthor

Mr. Yonghua Tan, China

Coauthor

Mrs. Feng Li, China

Year

2011

Abstract

The problems of overtesting and test damage observability have been of great interest to the liquid rocket engine design community leading to the notching technique. This technique essentially tries to experimentally prevent the structure from being overtested, but cannot 100% guarantee this from happening. The virtual vibration test means simulating a test prior to its physical happening. By carrying out such a virtual test, the test engineer can evaluate the test performance of the mentioned system prior to actually putting things into operation. This can help him first in defining the proper selection of all parameters involved in the experiment, accounting for a “smoother” test deployment. Moreover, this can lead him to nimbly correlate the mathematical models of the engine and gain a deeper insight about the overall system physics.
  In the study, the virtual shaker system is built up firstly. The rigid-body shaker is modeled using the physical parameters of the real electrodynamic shaker. The transfer functions of the output accelerations with the input voltages are derived using the bare shaker experiments. The parameterized models of the shaker are obtained using the curve fitting method. Based on the coupling technique of the rigid and flexible bodies, the virtual vibration test system is built.
  Then the liquid rocket engine is modeled with finite element method based on the dynamic optimization of the engine. The modal experiments for single liquid rocket engine are carried out to update the finite element model of the engine and perform the dynamic optimization of the framework of the engine. The updated finite element model of the engine will be used in the virtual vibration test.
  Finally the virtual open-loop control sine sweep test for the engine is presented based on the coupling of the rigid and flexible bodies. The shaker is modeled with rigid bodies and the engine including the fixture is modeled with finite element method. The signals inputting into the shaker are produced in the control simulation software. Results show that the virtual vibration test agrees well with the experiment near the big wave crests. The virtual vibration test could reappear and simulation results can also be displayed visually.
  The work proposed in the paper will be of benefit to the virtual environmental test of the liquid rocket engine.

Abstract document

IAC-11,C4,3,14,x10395.brief.pdf

Manuscript document

IAC-11,C4,3,13,x10395.pdf (🔒 authorized access only).

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