Liquid low-thrust rocket engine boundary layer numerical study

Аuthors

Vorob'eva S. S.

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

e-mail: Kinder-Svetiks@yandex.ru

Abstract

The subject of the work consists in numerical study of the boundary layer on the wall of the combustion chamber and nozzle of a liquid rocket thruster. Using numerical integration method of the system of differential equations describing the boundary layer, the boundary layer parameters were computed as a function of the engine operating conditions and the pressure in the combustion chamber. To close the system of boundary layer equations, the values of turbulent moment and heat transfer coefficients are calculated by determining mixing length by the equation suggested by Prandtl with Van Driyst correction.

A numerical method for the boundary layer computation was realized as a software with the working interface in Excel. The program operates with relative dimensionless parameters.

Low-thrust LRE, burning such fuel components as nitrogen tetroxide and asymmetrical dimethyl hydrazine with the thrust of 200 N, parameters served as initial data for computation. The working flow parameters were taken according to the results of thermal and gas dynamics computation with average mixture ratio “on the wall” over the length of combustion chamber.

The paper presents computation results of the boundary layer parameters for the MAI-200-1 object engine: the displacement thickness, relative velocity profile, friction coefficient, nozzle flow rate.

The change of boundary layer thickness and flow rate coefficient for the object engine, and engines with working pressure of 2 and 3 MPa were calculated. The paper made clear that an increase in the combustion chamber pressure increases the relative thickness of the boundary layer, while nozzle flow rate falls.

Keywords:

liquid low-thrust rocket engine, boundary layer, displacement thickness, relative velocity, friction coefficient, nozzle flow rate

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