120 research outputs found
The boundary layer on compressor cascade blades
The purpose of NASA Research Grant NSG-3264 is to characterize the flowfield about an airfoil in a cascade at chord Reynolds number(R sub C)near 5 x 10 to the 5th power. The program is experimental and combines laser Doppler velocimeter (LDV) measurements with flow visualization techniques in order to obtain detailed flow data, e.g., boundary layer profiles, points of separation and the transition zone, on a cascade of highly-loaded compressor blades. The information provided by this study is to serve as benchmark data for the evaluation of current and future compressor cascade predictive models, in this way aiding in the compressor design process. Summarized is the research activity for the period 1 December 1985 through 1 June 1986. Progress made from 1 June 1979 through 1 December 1985 is presented. Detailed measurements have been completed at the initial cascade angle of 53 deg. (incidence angle 5 degrees). A three part study, based on that data, has been accepted as part of the 1986 Gas Turbine Conference and will be submitted for subsequent journal publication. Also presented are data for a second cascade angle of 45 deg (an incidence angle of 3 degrees)
The measurement of boundary layers on a compressor blade in cascade at high positive incidence angle. 2: Data report
Boundary layer and near-wake velocity measurements have been made in the well documented flow field about a double circular arc compressor blade in cascade, at an incidence angle of 5 deg. and a chord Reynolds number of 500,000. In Part 2 of this report these measurements were analyzed and presented in standard graphical format. The flow geometry, measurement techniques, and physics of the flow field were also discussed. In this, part 2 of the report, raw and analyzed data are presented in tabulated form in an attempt to make this data more accessible to computational comparison. Also included in part 2 is a description of the data analysis employed. A computer tape containing the data is available
The measurement of boundary layers on a compressor blade in cascade at high positive incidence angle. 1: Experimental techniques and results
Measurements of the mean velocity and turbulence intensity were made using a one-component laser Doppler velocimeter in the boundary layer and near wake about a double circular arc, compressor blade in cascade. The measurements were made at a chord Reynolds number of 500,000. Boundary layer measurements on the pressure surface indicate a transition region over the last 40% of the chord. A small separation bubble near the leading edge of the suction surface results in an immediate transition from laminar to turbulent flow. The non-equilibrium turbulent boundary layer separates near the trailing edge of the suction surface. Similarity of the outer region of the turbulent boundary layer ceases to exist in the separated region. Also, similarity does not hold in the near-wake region, a region which includes negative mean velocities because of the separation near the trailing edge on the suction surface
The boundary layer on compressor cascade blades
The characteristics of the flow field about highly loaded turbocompressor blades in a cascade wind tunnel were investigated. Experimental tests were conducted at chord Reynolds number (R sub c) near 500,000. A laser Doppler anemometer was employed in flow velocity measurement. Suction surface mean velocity and turbulence intensity profiles at a single incidence angle are presented. These data contribute to further understanding of two-dimensional boundary layer profiles, points of separation, and transition zones for turbomachine blades, and concomitantly, to compressor cascade predictive models
The boundary layer on compressor cascade blades
The flow field about an airfoil in a cascade at chord Reynolds number (R sub C) near 50,000. The program is experimental and combines laser Doppler anemometry (LDA) with flow visualization techniques in order to obtain detailed flow data (e.g., boundary layer profiles, points of separation and the transition zone) on a cascade of highly-loaded compressor blades. The information provided is to serve as benchmark data for the evaluation of current and future compressor cascade predictive models, in this way aiding in the compressor design process. The completed pressure surface mean velocity profiles, as well as two detailed near wake velocity profiles, all at a single incidence angle are provided
Search for non-relativistic Magnetic Monopoles with IceCube
The IceCube Neutrino Observatory is a large Cherenkov detector instrumenting
of Antarctic ice. The detector can be used to search for
signatures of particle physics beyond the Standard Model. Here, we describe the
search for non-relativistic, magnetic monopoles as remnants of the GUT (Grand
Unified Theory) era shortly after the Big Bang. These monopoles may catalyze
the decay of nucleons via the Rubakov-Callan effect with a cross section
suggested to be in the range of to
. In IceCube, the Cherenkov light from nucleon decays
along the monopole trajectory would produce a characteristic hit pattern. This
paper presents the results of an analysis of first data taken from May 2011
until May 2012 with a dedicated slow-particle trigger for DeepCore, a
subdetector of IceCube. A second analysis provides better sensitivity for the
brightest non-relativistic monopoles using data taken from May 2009 until May
2010. In both analyses no monopole signal was observed. For catalysis cross
sections of the flux of non-relativistic
GUT monopoles is constrained up to a level of at a 90% confidence level,
which is three orders of magnitude below the Parker bound. The limits assume a
dominant decay of the proton into a positron and a neutral pion. These results
improve the current best experimental limits by one to two orders of magnitude,
for a wide range of assumed speeds and catalysis cross sections.Comment: 20 pages, 20 figure
The IceCube Neutrino Observatory Part VI: Ice Properties, Reconstruction and Future Developments
Papers on ice properties, reconstruction and future developments submitted to
the 33nd International Cosmic Ray Conference (Rio de Janeiro 2013) by the
IceCube Collaboration.Comment: 28 pages, 38 figures; Papers submitted to the 33nd International
Cosmic Ray Conference, Rio de Janeiro 2013; version 2 corrects errors in the
author lis
Determining neutrino oscillation parameters from atmospheric muon neutrino disappearance with three years of IceCube DeepCore data
We present a measurement of neutrino oscillations via atmospheric muon
neutrino disappearance with three years of data of the completed IceCube
neutrino detector. DeepCore, a region of denser instrumentation, enables the
detection and reconstruction of atmospheric muon neutrinos between 10 GeV and
100 GeV, where a strong disappearance signal is expected. The detector volume
surrounding DeepCore is used as a veto region to suppress the atmospheric muon
background. Neutrino events are selected where the detected Cherenkov photons
of the secondary particles minimally scatter, and the neutrino energy and
arrival direction are reconstructed. Both variables are used to obtain the
neutrino oscillation parameters from the data, with the best fit given by
and
(normal mass hierarchy assumed). The
results are compatible and comparable in precision to those of dedicated
oscillation experiments.Comment: 10 pages, 7 figure
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