Frequency Characteristics Computation of Liquid Rocket Engine Based on Distributed Parameter Models

Linearized distributed parameter models are used to compute frequency responses of liquid rocket engine.One-dimensional distributed parameter models are used to describe engine pipelines.Other engine components are described in lumped parameter models.The linearized models of engine pipelines and components are transformed to frequency domains.Engine elements frequency domain models are described as transmission matrixes,which relates input and output variables of the engine elements.Engine system is divided into several modules according to the connections between engine elements.Matrix transform methods are used to obtain module transmission matrixes from element transmission matrixes.Equations of engine system are constituted from module transmission matrixes.These equations relate system variables and disturbances.It is convenient to generate different rocket engine systems and compute their frequency characteristics according to their own structure and parameters.The frequency characteristics of a staged combustion cycle LOX/LH2 liquid rocket engine have been analyzed numerically.