Performance characteristics of a pintle nozzle using the conformal sliding mesh technique

Numerical and non-linear internal ballistics analyses are conducted to investigate the performance characteristics of a pintle reciprocating in a nozzle. A conformal sliding mesh is successfully implemented to maintain smooth and continuous flow properties at the boundary of a moving pintle block. The proper mesh size is determined via a grid dependency test. The pintle nozzle operates under over-expansion conditions so that flow separation occurs at the nozzle wall at certain pintle stroke positions. Both the chamber pressure and thrust have hysteresis loci to allow for the reciprocation of the pintle's insertion and extraction motions, which have different trace-to-pintle speeds. The hysteresis loci reduce as the pintle speed increases. The thrust coefficient (rather than the thrust itself) is able to precisely determine the effects of the nozzle flow separation on overall performance.