32 research outputs found
Vorticity estimation utilizing the rotation of finite line segments
Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.In a fluid flow field where velocities are measured or
numerically calculated, the vorticity value at a point in the
field is usually estimated by approximating partial
derivatives of velocity with ratios of velocity differences
and spatial differences. Based on the fundamental
definition of rotation, this paper presents an alternate
approach to estimate vorticity, by using the instantaneous
relative angular velocity of finite line segments radiating
from the point to adjacent points in the fluid.
The number, length and placement of line segments are
varied to find their effects on predicted vorticity values in
four laminar flow fields with known vorticity. Equations
are also derived for a configuration consisting of four
independent finite line segments which has application to a
square numerical velocity mesh and to instrumentation such
as hot wire vorticity probes and vane vorticity meters. The
results presented are relevant to both experimental and
computational fluid mechanics.cs201
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
A computational study of annular cascade flows using aq-ω turbulence model with a wall function
Effect of Space-Chord Ratio on the Endwall Flow in a Large Deflection Turbine Rotor Cascade with Tip Clearance
CD28-Directed T Cell Costimulation Blockade with Abatacept to Prevent GVHD During High-Risk Unrelated HSCT: A First-In-Disease Trial
Purge and Mainstream Flow Interaction Control by Means of Platform Circumferential Contouring
This study presents an attempt to reduce the losses produced by the purge flow in a turbine stage by incorporating circumferential platform contouring. Two contours are proposed and compared against a baseline at different levels of swirl. The computational simulations were performed using a RANS three-dimensional Computational Fluid Dynamics code with the Shear Stress Transport turbulence model. The results of steady simulations demonstrate that for the first contour, when the flow is swirled to 50% of the rim speed, the purge flow exits the cavity with less cross flow. This in turn reduces the strength of the passage vortex. However, at swirl extremes of 0% and 100% the baseline has the best perfomance. The results show that a carefully desgined platform could reduce losses when the operating condition is in the proximity of 50% swirl. © 2011 by Siemens Energy, Inc