Numerical simulation of ionized rocket plumes

In this paper, a multiphysics numerical approach for predicting the ionization level in solid rocket engine plumes is presented. Ionization takes place in the rocket combustion chamber and in the exhaust plume. A low-temperature, high-density plasma is created, with small Debye length in most of the plume region. Ambipolar diffusion is therefore assumed for ions and electrons in the plume, and a set of conservation equations is derived to be solved by the numerical model. A number of numerical strategies to resolve this system is derived, as well as a novel scheme that enforces chargeneutrality. This approach is integrated into a complex code for compressible, multispecies, turbulent flow simulations. The model is then coupled with a Maxwell's equations solver in order to simulate the radar cross section of rocket plumes. Finally, computations of ionization levels and radar cross section of a Black Brant rocket plume are presented.