Download RTE, Rocket Thermal Evaluation

cooled, high-pressure engine, axial conduction may be significant. Thus, the accuracy in
the axial direction may be set to 0.1% and 0.1% in the other directions.
DESCRIPTION OF THE COMPUTER CODE RTE
Rocket Thermal Evaluation (RTE) and its radiation module are written in standard
FORTRAN. The numerical model of RTE is based on the numerical method discussed in
the previous section. The program provides the temperature distribution in the rocket
thrust chamber and nozzle. It also calculates the rate of heat transfer to the cooling
channel, coolant temperature and pressure drop. This program can be used for all types of
propellants and coolants that are used in regeneratively cooled rockets. The conductivities
of several rocket engine materials are included in tabular form as functions of
temperatures. These include: Copper, Nickel, Soot (Carbon), NASA-Z (NARloy-Z),
Columbium, Zirconia, SS-347, Amzirc, Platinum, Glidcop, Inconel718 and Nicraly. The
user can specify conductivities of up to three materials in the input of the RTE . Three
options are available for the boundary condition at the outside surface: radiative, natural
convective, and forced convective boundary conditions. For the radiative and convective
boundary conditions, the outer surface emissivity and convective heat transfer
coefficients, respectively, must be specified. The boundary conditions at the inner surface
are combined convection and radiation heat transfer from hot gases and other surfaces.
The convective heat flux for the hot-gas-side can be specified in the input file. This
feature allows the user to interface RTE to the other codes for the hot-gas-side properties
and boundary layer analysis. The procedure for linking RTE to a hot-gas-side program
will be explained later.
RTE uses three major subprogram modules, hot-gas-side properties (BONNIE, which is a
modified CET [1]), coolant properties (GASP, WASP and RP1) and conduction
subprogram (COND). Subroutine BONNIE (CET) is for evaluation of thermodynamic
and transport properties of combustion gases. A complete description of this subprogram
is given in [1] and [2]. Subroutine BONNIE is only capable of predicting hot-gas
properties at equilibrium conditions. The combustion in the thrust chamber, however, is a
gradual process and might not reach the equilibrium condition within the thrust chamber.
As a result of this, the model over-predicts temperatures close to the injector, and a large
discrepancy between the computational and experimental temperatures is observed in this
part of the engine. To overcome this problem, provisions have been made such that one
can input the percentage of fuel burned at each station. Using this option, a low mixture
ratio is assigned to the stations close to the injector and is gradually increased to its actual
value at stations closer to the throat. The value of mixture ratio at each station depends on
the injector and chamber geometries, manifold conditions and many other parameters. To
predict the mixture ratio at each station, the user may use ROCCID (ROcket Combustor
Interactive Design and Analysis Computer Program) [5]. ROCCID uses state-of-the-art
codes and procedures for the analysis of a liquid rocket engine combustor's steady state
combustion performance and combustion stability. Modifications have been made on
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