Meeting Review: Airborne Aerosol Inlet Workshop

Proceedings from the Airborne Aerosol Inlet Workshop are presented. The two central topics of discussion were the role of aerosols in atmospheric processes and the difficulties in characterizing aerosols. The following topics were discussed during the working sessions: airborne observations to date; identification of inlet design issues; inlet modeling needs and directions; objectives for aircraft experiments; and future laboratory and wind tunnel studies

Aeronautical Engineering: A continuing bibliography with indexes (supplement 175)

This bibliography lists 467 reports, articles and other documents introduced into the NASA scientific and technical information system in May 1984. Topics cover varied aspects of aeronautical engineering, geoscience, physics, astronomy, computer science, and support facilities

Annual Report of the National Advisory Committee for Aeronautics (42nd), Administrative Report without Technical Reports

No abstract availabl

Overhauling Sound Diffusion in Auditoria Using Deep-Subwavelength Acoustic Metamaterials

The reducedamount of space available in critical listening environments, such as orchestra pits, rehearsal rooms or even recording studios, often impairs the installation of helpful, but sizeable, acoustic treatments on their boundaries. This can be a problem as such acoustic treatments, mainly used for sound absorption and diffusion, are key for controlling the physical aspects of sound propagation in the environment. This research thus proposes to study experimentally and numerically a cutting-edge metamaterial-inspired approach designed to provide ultra-thin and adaptable alternatives to traditional acoustic treatments, with a particular focus on sound diffusion, and how these can be integrated in practical computational frameworks. These novel deep-subwavelength acoustic metamaterials, termed metadiffusers, allow for efficient sound diffusion within dimensions 1/10th to 1/20th thinner than ordinary sound diffusers. Moreover, the optimization potential of metadiffusers brings a vast panel of variable configurations depending on the situation requirements. Results presented throughout this thesis outline several of these configurations with experimental and/or numerical validations in free-field scattering scenarios as well as numerical room acoustic applications. Very good agreement is found all through between the analytical and experimental/numerical scattering and diffusion datasets, thus demonstrating the outstanding and versatile potential of metadiffusers to be applied in many critical listening environments where space is at a premium, such as orchestra pits or recording studios

The effect of oblique entry into an automotive catalyst on the flow distribution within the monolith

Automotive catalytic converters are increasingly used to reduce emissions from internal combustion engines to comply with emission regulations. Maldistributed flow across the catalyst affects its warm up light off time, ageing, and conversion efficiency. This thesis concerns flow distribution in automotive catalytic converters and methods to improve CFD predictions. Previous studies showed that modelling the monolith flow resistance using the HagenPoiseuille's formulation under predicted flow maldistribution. The predictions were improved by incorporating an additional pressure loss term..!.py2, where Y .is 2 transverse velocity just upstream of a monolith channel, for oblique entry ofthe flow into the monolith known as the entrance effect. Further improvement was.obtained by incorporating the critical angle ofattack method. However, there was no experimental evidence to support these oblique entry loss formulations. There also remained the possibility that under predictiqn offlow maldistribution might be due to the failure to predict flow in the diffuser accurately. A one-dimensional oblique angle flow rig was designed and built to measure the effect of oblique entry flow losses. in monoliths. Experiments were performed at different angles of attack (a), using different lengths of substrate and a methodology was developed to obtain the oblique flow entrance losses. The results showed that the pressure loss attributed to the entrance effect increased with the angle of attack. The entrance effect was also found to be dependent on channel Reynolds number and substrate length. The theoretical assumption of ..!.py2 predicts accurately at low 2 Reynolds number but looses its validity at high Reynolds number. From the experimental studies, an improved correlation for the entrance effect has been derived as a function of major controlling variables, i.e~, angle of .attack, length of the substrates and Reynolds number. A two-dimensional rig was designed to measure the flow field using PN in a 2-D diffuser placed upstream of two different length substrates. The results showed that the flow in;~ wide angle diffuser consisted of a central core, free shear layer and recirculation regions. The near-fiela region was· found 'similar to that of a plane jet. The flow field was found to be independent of Reynolds number. Increasing the substrate length resulted in a flattening ofthe axial profiles close to the substrate face. A CFD study was undertaken to predict maldistributed flow at the exit ofthe substrate for an axisymmetric catalyst model by incorporating the measured entrance effect correlation. A fixed critical angle of attack (flc,F) approach was used whereby the entrance effect is assumed constant for a>0<:,F. Incorporating the entrance effect with O<:,r 810 improved the prediction ofmaldistribution in the flow profiles. A 2-D CFD study was undertaken to predict the flow distribution in the diffuser and downstream of the substrate. A ~mparison of the CFD predictions in the diffuser using different turbulence models showed that all the turbulence models used in this study over predicted the width of the central core region and the V2F turbulence model. gave velocity predictions that compared best with PIV. Incorporating the entrance effect improved the predictions close to the diffuser-substrate interface and downstream ofthe substrate.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Aeronautical engineering: A continuing bibliography with indexes (supplement 256)

This bibliography lists 426 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1990. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Defense Technical Information Center thesaurus

This DTIC Thesaurus provides a basic multidisciplinary subject term vocabulary used by DTIC to index and retrieve scientific and technical information from its various data bases and to aid DTIC`s users in their information storage and retrieval operations. It includes an alphabetical posting term display, a hierarchy display, and a Keywork Out of Context (KWOC) display

Aeronautical Engineering: A continuing bibliography with indexes, supplement 99

This bibliography lists 292 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1978

Aeronautical engineering: A continuing bibliography with indexes (supplement 223)

This bibliography lists 423 reports, articles, and other documents introduced into the NASA scientific and technical information system in January, 1988

Aeronautical engineering: A continuing bibliography with indexes (supplement 237)

This bibliography lists 572 reports, articles, and other documents introduced into the NASA scientific and technical information system in February, 1989. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics