Devlopment and Study of Weather Effects in a High-Speed Wind Tunnel

In order for high-speed systems to develop an all-weather readiness, the effect of weather induced disturbances on aerothermodynamic phenomena for high-speed vehicles must be closely studied. At supersonic and hypersonic flight conditions, the introduction of weather disturbances having hypervelocity impacts can damage a vehicle in several ways. This could include penetrating the vehicle surface, altering the performance of air breathing engines, or severely disrupting shockwave interactions and boundary layer dynamics. In order to develop an understanding of unique flow environments that can be experienced in flight, ground test facilities are used to replicate critical phenomena, including particle interactions. Currently, there are few wind tunnel facilities that have capabilities of creating weather environments. Many of the facilities that currently have this implementation are located at national laboratories and government facilities which require high operation costs. This thesis seeks to implement a method for creating freestream borne particulates with reduced cost and complexity to make studying weather effects more accessible in common ground test facilities. The presented method involves injecting water droplets upstream of a supersonic wind tunnel’s converging-diverging nozzle, allowing the droplets to accelerate to similar speeds of the freestream air flow, and be observed as a randomly distributed droplet field in the test section. The results of this study are divided into two key investigations. First, many features of the droplet injection technique and their ability to resemble conditions similar to what could be seen in flight are characterized using numerical analysis and optical/laser diagnostics. After the droplets were characterized, an in-depth study analyzed how a droplet environment could alter shockwave structures including shockwave boundary- layer interactions (SBLI). The results showed that droplets can strongly promote boundary layer transition, thus altering inherently unsteady shockwave features of an SBLI.