Experimental Investigation on Microwave Interference in Full-Scale Solid Rocket Exhaust

摘要

Under certain conditions during rocket flight, ionized exhaust plumes from solid rocket motors may interfere with RF transmission. To understand the relevant physical processes involved in this phenomenon, measurement of microwave attenuation and phase delay caused by rocket exhaust plumes was attempted in a sea-level static firing test for a full-scale solid propellant rocket motor. The measured data were analyzed by comparing them with simulation results for an exhaust plume flowfield. The results revealed that the change in the shock structure in the plume affects the microwave attenuation level, since it significantly affects the plasma density at the measuring location. When the plasma density in the plume is low, the microwaves can penetrate the plume. The plume plasma properties were successfully estimated for that situation in which the numerically calculated attenuation level agreed well with the experimental results. On the other hand, high-density plasma in the plume does not allow penetration. Therefore, microwaves bypass around the plume and the diffraction effect becomes dominant.