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Metrology

Flow metrology and rheology

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Displaying 126 - 150 of 184

Relaxation Effects in Small Critical Nozzles

January 1, 2006
Author(s)
Aaron N. Johnson, C L. Merkle, Michael R. Moldover, John D. Wright
We computed the flow of four gases (He, N 2, CO 2, and SF 6) through a critical nozzle by augmenting traditional computational fluid dynamics (CFD) with a rate equation that accounts for τ relax, a species-dependent relaxation time that characterizes the

Gas Flowmeter Calibrations with the 34 L and 677 L PVTt Standards

June 23, 2004
Author(s)
John Wright, Aaron Johnson, Michael Moldover, Gina Kline
This document provides a description of the 34 L and 677 L pressure, volume, temperature, and time (PVTt) primary gas flow standards operated by the National Institute of Standards and Technology (NIST) Fluid Flow Group. These facilities are used to

Fluorescence Thermometry in Microfluidics

September 29, 2003
Author(s)
David J. Ross, Laurie E. Locascio
Two techniques are described for the measurement of fluid temperatures in microfluidic systems based on temperature-dependent fluorescence. In the first technique, a single, strongly temperature-dependent fluorophore, rhodamine B, is used as the basis for

Liquid Agent Transport Around Solid Obstacles

May 1, 2002
Author(s)
Cary Presser, J F. Widmann, G Papadopoulos
The focus of this effort is to investigate the dispersal of liquid fire suppression agents around solid obstacles, and obtain a better understanding of the physical processes of droplet transport in cluttered spaces. An experimental investigation is

Speed of Sound as a Thermodynamic Property of Fluids

September 15, 2001
Author(s)
Daniel G. Friend
In this chapter, we review the principles of sound propagation in fluid systems. From a study of the hydrodynamic equations, sound propagation is shown to be a wave phenomenon. The speed of sound then can be derieved at any state point from a knowledge of

Mass Flow Research and Standards: NIST Workshop Results

July 1, 2001
Author(s)
Robert F. Berg, David S. Green, G E. Mattingly
A recent workshop at the National Institute of Standards and Technology (NIST) identified research and standards that will benefit users and manufacturers of mass flow controllers and related equipment. The workshop identified problems with flow

Vapor Entraining Magnetic Mixer for Reaction and Equilibrium Applications

March 1, 2001
Author(s)
Thomas J. Bruno, Michael C. Rybowiak
Mixing of fluids is a central component to innumerable operations in chemical processing on the plant floor and also in many laboratory operations. Most mixing applications simply require the efficient blending of fluids present in a single phase, such as

Evanescent-Wave Cavity Ring-down Spectroscopy for Trace Water Detection

February 1, 2001
Author(s)
A C. Pipino, Joseph T. Hodges
We explore the use of evanescent wave cavity ring-down spectroscopy (EW-CRDS) for water detection through a signal-to-noise ratio analysis. Cavity ring-down spectroscopy (CRDS) is an emerging optical absorption technique that employs the mean photon decay

Laminar Flow of Four Gases Through a Helical Rectangular Duct

February 1, 2001
Author(s)
Robert F. Berg, S A. Tison
We report measurements and a model of gas flow through a helical duct of rectangular cross section. The measurements on helium, nitrogen, argon, and sulfur hexafluoride yielded molar flow rates from observations of the rate of rise of pressure in a known

Control of Flow Direction in Microfluidic Devices with Polyelectrolyte Multilayers

December 1, 2000
Author(s)
S L. Barker, David J. Ross, Michael J. Tarlov, Michael Gaitan, Laurie E. Locascio
Electroosmotic flow (EOF) is commonly utilized in microfluidics. Because the direction of the EOF can be determined by the substrate surface charge, control of the surface chemical state offers the potential, in addition to voltage control, to direct the

Aerodynamic Study of a Vane-Cascade Swirl Generator

November 1, 2000
Author(s)
J F. Widmann, S R. Charagundla, Cary Presser
The air flow through a vane-cascade swirl generator is examined both experimentally and numerically to characterize the inlet combustion air flow entering a reference spray combustion facility at NIST. A three-dimensional model is used to simulate the

Laboratory Primary Standards

April 1, 2000
Author(s)
John D. Wright
Commonly used primary calibration techniques for the measurement of liquid and gas flows are described. The techniques described include: static gravimetric and dynamic gravimetric methods for both gases and liquids, liquid piston displacement provers
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