An analysis of direct solar thermal rocket propulsion

A two-dimensional analysis is performed to model the radiation-gasdynamic interaction in a direct solar absorption rocket thruster. The direct absorption from the beam is Modelled using a ray-tracing technique. A “thick-thin” model is employed to account for reradiation from the hot gas. Detailed spectral variation of the absorption coefficient is incorporated in the model. Navier-Stokes calculations are carried out in the nozzle region to determine the appropriate nozzle throat size. Results indicate that radiation losses from the plasma may be significant. Further, the energy left unabsorbed in the beam is also incident on the wall. These wall losses may be recovered by regenerative cooling of the walls by the working fluid. For such a scheme, coupling efficiencies up to 90% seem possible for optimum flow rates.