Design of Conventional and Detonation-Driven Hypervelocity Expansion Tubes

Freestream disturbances can have a significant impact on studies of boundary layer transition in ground tests, including experiments in high-enthalpy hypersonic facilities such as an expansion tube. Freest ream noise reduction in expansion tubes can be achieved by increasing the driver-to-driven pressure ratio p₄/p₁, so we seek .methods to increase this ratio in Caltech's HET facility. Towards this end, an in-house modular parametric code has been developed using Python to explore possible modifications to the HET. The effect of increasing the pressure in a passive driver on potential noise reduction is investigated. Optimization of acceleration section length is also explored for conventional drivers. The performance of detonation drivers using H₂ and C₂H₂ fuels with He, Ar, and CO₂ diluents is examined.