Numerical simulation of chemically non-equilibrium flow in the nozzle of the liquid-propellant rocket engine

Аuthors

Gidaspov V. Y.

e-mail: gidaspov@mai.ru

Abstract

The object of research

Chemically reacting flows in rocket nozzles.

Theme

Computational and theoretical study of chemical equilibrium and nonequilibrium flow in the nozzle of a liquid rocket engine

Purpose

The article aims are development of physical and mathematical models, computational algorithms and software system for the solution of the direct problem of the theory of the nozzle for the case chemically reacting flows and calculation of the parameters of chemical equilibrium and non-equilibrium flows, determination of the loss of specific impulse of the nozzle due to the chemical non-equilibrium, the concentration of toxic components.

Method of investigation

Mathematic modeling.

Results

Physical and mathematical models, computational algorithms and software package for solving the direct problem of the theory of the nozzle in the presence of non-equilibrium chemical reactions in the quasi stationary setting are obtained. Computational algorithm passing the singular point, which includes three stages and ensures that the condition of non-decreasing entropy is received. In the first stage the flow rate corresponding to the non-equilibrium flows in the nozzle where the regime «lock» the current was implemented (curve 1) and Mach number of the flow was, as close to one in subsonic flow (curve 2) was determined.
In this case, all parameters of the flow along the curves 1 and 2 were almost identical up to a small neighborhood of the transition through the speed of sound.
In the second stage, instead of the equation of conservation of momentum the constancy of the velocity 

Dependence of the speed (1-3) and the speed of sound (4) of the products of combustion from the longitudinal coordinates (1 mode «lock» the flow 2 subsonic flow regime, 3 passing the singular point)

gradient was used, the calculation with which provided the condition of non-decreasing entropy.
The appropriate starting point was taken on the curve 2. The solution was carried out to achieve supersonic flow and the condition of positivity of the velocity gradient, obtained from the conservation momentum equation of. In the third phase the direct problem for supersonic flow was solved.
Numerical simulation of combustion unsymmetrical dimethyl hydrazine with nitrogen tetroxide in range of oxidant-fuel ratio 0.8 — 1.2, and the pressure in the combustion chamber 2 MPa - 20 MPa. Obtained The difference «non-equilibrium» flow rate from the «equilibrium», the value of specific impulse loss and the coordinates of the transonic at «non-equilibrium» flow are obtained.
Field of application of the results and conclusions.
Developed computational algorithms and computer programs can be used for designing advanced propulsion systems.

Keywords:

numerical simulation, the direct problem of the theory of the nozzle, chemical reactions, loss of specific impulse

References

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