22,403 research outputs found
High heat flux measurements and experimental calibrations/characterizations
Recent progress in techniques employed in the measurement of very high heat-transfer rates in reentry-type facilities at the Arnold Engineering Development Center (AEDC) is described. These advances include thermal analyses applied to transducer concepts used to make these measurements; improved heat-flux sensor fabrication methods, equipment, and procedures for determining the experimental time response of individual sensors; performance of absolute heat-flux calibrations at levels above 2,000 Btu/cu ft-sec (2.27 kW/cu cm); and innovative methods of performing in-situ run-to-run characterizations of heat-flux probes installed in the test facility. Graphical illustrations of the results of extensive thermal analyses of the null-point calorimeter and coaxial surface thermocouple concepts with application to measurements in aerothermal test environments are presented. Results of time response experiments and absolute calibrations of null-point calorimeters and coaxial thermocouples performed in the laboratory at intermediate to high heat-flux levels are shown. Typical AEDC high-enthalpy arc heater heat-flux data recently obtained with a Calspan-fabricated null-point probe model are included
Dissipative phenomena in extended-bodies interactions I: Methods Dwarf galaxies of the Local Group and their synthetic CMDs
Dissipative phenomena occurring during the orbital evolution of a dwarf
satellite galaxy around a host galaxy may leave signatures in the star
formation activity and signatures in the colour magnitude diagram of the galaxy
stellar content. Our goal is to reach a simple and qualitative description of
the these complicated phenomena. We develop an analytical and numerical
technique able to study ram pressure, Kelvin-Helmholtz instability,
Rayleigh-Taylor and tidal forces acting on the star formation processes in
molecular clouds. We consider it together with synthetic colour magnitude
diagrams techniques. We developed a method to investigate the connections
existing between gas consumption processes and star formation processes in the
context of the two extended-body interaction with special attention to the
dwarf galaxies dynamical regime.Comment: Accepted on A&
Optical measurements of fluctuating temperatures in a supersonic turbulent flow using one- and two-photon, laser-induced fluorescence
A laser-induced fluorescence technique was developed that provides a practical means of nonintrusively measuring the instantaneous temperatures in low-temperature turbulent flows. The capabilities of the method are reviewed, and its application to a simple, two-dimensional, turbulent boundary-layer flow at Mach 2 is reported. Measurements of the average temperature distribution through the boundary layer and the magnitudes of temperature fluctuations about their average values are presented
Conduct disorder : the achievement of a diagnosis'
This paper explores the historical shapings behind the diagnosis of conduct disorders. We take as our point of purchase oppositional ways of knowing the subject of conduct disorder—as either pathologically motivated or as the victim of a repressive mandate to control disorderly conduct. We take our cue from Foucault's suggestion that the pursuit of singular motivations behind a phenomenon is not the most fruitful means of understanding its historical appearance. We explore the emergence of the individual with conduct disorder as an appearance contingent upon dispersed agencies of government—an artefact of dispersed technologies for channelling and directing a population
A feasibility study of using Langley 0.3-m transonic cryogenic tunnel sidewall boundary-layer removal system for heavy gas testing
This report presents the results of a preliminary study for using the 0.3-m Transonic Cryogenic Tunnel sidewall boundary-layer removal system with heavy gas sulfur hexafluoride as the test medium. It is shown that the drive motor speed/power of the existing system and the additional heat load on the tunnel heat exchanger are the major problems limiting the boundary-layer removal system performance. Overcoming these problems can provide the capability to remove about 1.5 percent of the test section mass flow at Mach number M = 0.8 and about 5 percent at M = 0.25. Previous studies have shown that these boundary-layer mass flow removal rates can reduce the boundary-layer thickness by a factor of two at the model station. Also the effect of upstream boundary-layer removal on the airfoil test data is not likely to be significant under high lifting conditions. Near design conditions, corrections to the test Mach number may be necessary to account for sidewall boundary-layer effects
Viscous Flow in Domains with Corners: Numerical Artifacts, their Origin and Removal
We show that an attempt to compute numerically a viscous flow in a domain
with a piece-wise smooth boundary by straightforwardly applying well-tested
numerical algorithms (and numerical codes based on their use, such as COMSOL
Multiphysics) can lead to spurious multivaluedness and nonintegrable
singularities in the distribution of the fluid's pressure. The origin of this
difficulty is that, near a corner formed by smooth parts of the piece-wise
smooth boundary, in addition to the solution of the inhomogeneous problem,
there is also an eigensolution. For obtuse corner angles this eigensolution (a)
becomes dominant and (b) has a singular radial derivative of velocity at the
corner. A method is developed that uses the knowledge about the eigensolution
to remove multivaluedness and nonintegrability of the pressure. The method is
first explained in the simple case of a Stokes flow in a corner region and then
generalised for the full-scale unsteady Navier-Stokes flow in a domain with a
free surface.Comment: Under consideration for publication in the Journal of Fluid
Mechanics. Figure bouding box problems resolve
A Study of Ablation-Flowfield Coupling Relevant to the Orion Heatshield
The coupled interaction between an ablating surface and the surrounding aerothermal environment is studied. An equilibrium ablation model is coupled to the LAURA flowfield solver, which allows the char ablation rate (m-dot(sub c)) to be computed as part of the flowfield solution. The wall temperature (T(sub w)) and pyrolysis ablation rate (m-dot(sub g)) may be specified by the user, obtained from the steady-state ablation approximation, or computed from a a material response code. A 32 species thermochemical nonequilibrium flowfield model is applied, which permits the treatment of C, H, O, N, and Si containing species. Coupled ablation cases relevant to the Orion heatshield are studied. These consist of diffusion-limited oxidation cases with Avcoat as the ablation material. The m-dot(sub c) values predicted from the developed coupled ablation analysis were compared with those obtained from a typical uncoupled ablation analysis. The coupled results were found to be as much as 50% greater than the uncoupled values. This is shown to be a result of the cumulative effect of the two fundamental approximations inherent in the uncoupled analysis
A 'third way' in industry training: New Zealand's adaptation of selected British policies
This article has three integrated purposes. It seeks to provide insights into some of the ways in which:
British policies and programmes historically and more recently have influenced New Zealand initiatives in industry training;
those policies and programmes have been adapted to meet the country’s particular circumstances; and
unions have influenced aspects of the adaptation and implementation
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