Features of mathematical simulation of gas path dynamics in the problem of the stability of low-frequency processes in liquid-propellant rocket engines
Journal Title: Технічна механіка, Техническая механика, Technical Mechanics - Year 2017, Vol 3, Issue 3
Abstract
One of the important problems in the designing of liquid-propellant rocket engines (LPREs) is the study of the stability of low-frequency processes in LPREs by mathematical simulation. In the low-frequency range, the dynamics of most of the LPRE components is described by ordinary differential equations (ODEs). The exception is the LPRE gas paths: a combustion chamber, a gas generator and gas lines, processes in which are described by delay equations. Since low-frequency oscillations in LPREs may be caused by the instability of processes in some of the LPRE systems, in the numerical study of stability the LPRE must be considered as a multi-loop dynamic system with potentially instable subsystems. An efficient method to study the stability of such systems in linear formulation is based on calculating the eigenfrequency spectrum of the operator matrix of a linear system of ODEs; however, that method is oriented to dynamic systems described by ODEs. To apply it to the analysis of the LPRE low-frequency stability, in the mathematical model of gas path dynamics one has to go from delay equa-tions to ODEs. This paper addresses the problem of accounting for delays in the analysis of the LPRE low-frequency stability from the matrix spectrum. Schemes are constructed for approximate replacement of delay equations with ODEs based on approximating the delay element transfer function in a small parameter region by fractional rational functions and chains of functions. Different approximants of the delay element transfer func-tion are considered and compared with one another. A rational approach to accounting for delays in the equations of LPRE gas path dynamics is proposed, and methodological recommendations on accounting for them are formulated. The results of this study may be used in simulating the low-frequency dynamics of gas paths and analyzing the stability of low-frequency processes in LPREs.
Authors and Affiliations
N. Khoriak, S. Dolhopolov
Keywords
Related Articles
- EP ID EP344811
- DOI -
- Views 56
- Downloads 0
Dynamic instability of stiffened conic fairings for launch vehicles in supersonic gas flow
Vibrations of launch vehicle conical fairings stiffened by rings in the gas flow are investigated. Fairings are simulated using thin conic shells stiffened by inner rings. Losses in a dynamic structural stability corresp...
Rational selection of parameters of dynamic damper of longitudinal vibrations of liquid launch vehicle
A significant increase in amplitudes of elastic longitudinal vibrations of a launch vehicle (LV) occurring in losses in longitudinal stability of liquid LVs may be responsible for an emergency. Measures for providing lon...
On the adaptation of bifunctional systems of liquid-propellant rocket thrust vector control to modern methods and systems of space rocket stage flight control
The aim of this paper is to demonstrate that bifunctional rocket trust vector control systems can easily be adapted to modern flight control systems of space rocket stages with mass asymmetry that changes during the flig...
System for contactless removal of space debris from near-earth orbits using aerodynamic compensator
The purpose of the work is to validate the proposed system for contactless removal of space debris from near-earth orbits using an aerodynamic compensator. The technical solution associated with the space ion-beam shephe...
Simulation of mechanical processes in systems and units of aerospace engineering products
The literature on the simulation of mechanical processes in systems and units of aerospace engineering products is reviewed. The increasing structural complexity of the simulated objects, the interdisciplinary nature of...