Numerical code to analyze chemical reacting flows in the solid fuel ramjet engine combustor has been developed. LU-SSOR implicit scheme with finite volume method is used to solve the Navier-Stokes equations fully coupled with the chemical species continuity equations. Reduction of dimension of the implicit operator is made by Steger-Warming flux vector splitting plus lower-upper factorization. The explicit operators are differenced by central scheme.
Polyethylene is used as solid fuel and chemical reactions are modeled by a 6 species, 2-step finite chemistry. The turbulence is treated by the Baldwin-Lomax algebraic model while the radiative transfer equation is solved by finite volume method.
Four test problems are solved to verify this numerical code as follows. (1) Axisymmetric compressible flows in the JPL nozzle. (2) Chemically reacting flows over 2-D compression ramped duct. (3) Radiative heat transfer in a sylindrical enclosure containing absorbing, emitting media. (4) Radiative affected compressible turbulent flow over a backward facing step.
After code verification, the variations of chemically reacting flows in the solid fuel ramjet combustor, mean solid fuel regression rate and thrust for the inflow conditions and combustor geometries are investigated without and with considering the effect of radiation.
The summaries of main results are as follows. (1) Mean regression rate of solid fuel is proportional to inlet air mass flow rate and inlet air temperature but not to inlet pressure. (2) Thrust is proportional to inlet air mass flow rate and inlet pressure but inversely to inlet air temperature. (3) As the step height of combustor inlet decreases, the regression rate reduces, but thrust increases due to increase of inflow air density. (4) Thrust increases as the length of fuel grain increases. (5) Thust increases as the step height and the length of aft mixing chamber increases respectively. (6) The effect of radiative heat transfer plays a very important role in SFRJ combustor reacting flows. (7) To enhance the efficiency of SFRJ combustor, bypass air injection into aft mixing chamber is needed.
