After Math - Foamology and Flight Rationale

The Space Shuttle was developed by NASA to be a largely reusable launch system which could provide frequent access to low earth orbit. Like all previous launch systems, safe reentry for the crew and payload required the use of a thermal protection system (TPS). Unlike previous spacecraft though, the Shuttle's TPS was exposed from launch, making it sensitive to debris which could be generated by the vehicle on ascent. The most likely and potentially destructive source of debris was considered to be ice, which could build-up anywhere on the External Tank (ET) where there was exposed metal. Ice could form during ground operations after the cryogenic propellants had been loaded and then be knocked loose on ascent. In order to prevent both ice build-up and boil-off of the propellants, the entire ET and all protuberances (orbiter attach points, pressurization lines, propellant feed lines, etc.) were covered with a spray on foam insulation (SOFI) type TPS. Unfortunately the foam was also susceptible to liberation during ascent, and posed a debris risk of its own. During the early years of the Shuttle Program engineers spent a good deal of effort characterizing the amount of foam that was shed

Overview of SLS Aeroacoustic Environment Development

The Space Launch System (SLS) ascent aeroacoustic environments provide the externally driven noise levels predicted for vehicle ascent during transonic and supersonic flight, and serve as an important input for component and secondary structure vibroacoustic design criteria. This aerodynamically induced noise is predominantly generated by unsteady flow within the local boundary layer due to free stream interaction with the outer mold line (OML). Additional sources are shear flow interactions, shocks, protuberance flows, and wake flows. This presentation provides an overview of the aeroacoustics discipline along with the SLS environment development process, including wind tunnel testing and general data reduction methods. The state of the discipline is also presented with a summary of aeroacoustic measurement and computational techniques currently on the horizon

Space Launch System: SLS Aeroacoustic Wind Tunnel Test Results

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Space Launch System Aeroacoustic Wind Tunnel Test Results

Characterization of accurate launch vehicle unsteady aerodynamics is critical for component and secondary structure vibroacoustic design. For the National Aeronautics and Space Administration (NASA) Space Launch System (SLS), aeroacoustic environments have been derived primarily through sub-scale wind tunnel testing. Both optical techniques and high frequency pressure measurements have been utilized across multiple testing facilities and numerous vehicle configurations to develop a range of preliminary and detailed environments. As the vehicle has matured and evolved, the data collected from each subsequent configuration has allowed for comparison studies which isolate the effects of certain outer mold line (OML) features on measured fluctuating pressure levels. This paper presents observations on some of those effects for features which include abort system protuberances, various fairings geometries, interstage flanges, and multibody interactions between a central core and fall away boosters. These features, and the flow conditions produced by them, are broadly applicable to many launch vehicle configurations

Melt Dispersion Technique for Encapsulation

Encapsulation involves the coating or entrapment of a pure material or a mixture into another material. The coated or entrapped material, usually a liquid, is known as the “core” or “active” material, while the coating material is known as the “wall” material.1 At the end of any applicable technique for encapsulation, the nal products called particles (micro-or nanoparticle depending on the size) can be dried or not.2 Considering the aforementioned facts, a number of technologies have been used in the preparation of encapsulates, such as spray-drying, uidized-bed coating, spray-cooling, extrusion technologies, emulsication, inclusion encapsulation, coacervation, nanoencapsulation, and liposome entrapment. There are a number of excellent recent reviews summarizing all encapsulation processes.2-8 Although the principle of dispersing of a molten matrix has been frequently employed for production of encapsulates, there are not many, if any, papers overviewing the processes and equipments utilizing this principle. The aim of this chapter is to describe technologies utilizing melt dispersion, melt spraying, melt emulsication, and melt homogenization. It also surveys applications of melt dispersion, describes its advantages and limitations, and emphasizes trends and innovations