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Search Publications by: Aaron Johnson (Fed)

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Displaying 76 - 100 of 107

The Calculation of Natural Gas Viscosity

August 14, 2009
Author(s)
Aaron N. Johnson, William Johansen
The calculation of natural gas viscosity has been implemented many different ways including the use of constants. Different methods of calculating natural gas viscosity may produce values with differences as large as 50%. Increasing natural gas prices

Natural Gas Flow Calibration Service

August 1, 2008
Author(s)
Aaron N. Johnson
This document describes NIST's high pressure natural gas flow calibration service (NGFCS). Flow calibrations are conducted offsite at the Colorado Experimental Engineering Station Incorporated (CEESI) in Garner, Iowa. A parallel array of nine turbine meter

Comparisons by PTB, NIST, and LNE-LADG in Air and Natural Gas With Critical Venturi Nozzles Agree Within 0.05 %

May 16, 2006
Author(s)
B Mickan, Roland H. Kraemer, D Dopheide, Hans-Jurgen Hotze, Heino-Michael Hinze, Aaron Johnson, John D. Wright, J-P Vallet
The PTB, NIST, and LNE-LADG conducted a comparison of gas flow measurement standards in air and natural gas in the pressure range from 0.9 to 42 bar. The artifacts used in the intercomparisons were four critical venturis with ISO standard toroidal shape

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

Uncertainty and Traceability for the CEESI Iowa Natural Gas Facility

September 1, 2004
Author(s)
Aaron N. Johnson, Tom Kegel
This paper presents an uncertainty analysis for the CEESI Iowa natural gas calibration facility. This facility calibrates flow meters up to flows of 10.7 actual m3/s, at nominal pressures of 174 kPa. Flow meters are calibrated by a set of nine turbine

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

June 23, 2004
Author(s)
John D. Wright, Aaron N. Johnson, Michael R. Moldover, Gina M. 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

Volumetric Gas Flow Standard with Uncertainty of 0.02% to 0.05%

November 1, 2003
Author(s)
John D. Wright, Michael R. Moldover, Aaron N. Johnson, A Mizuno
A new pressure, volume, temperature, and time (PVTt) primary gas flow standard for calibrating flowmeters has an expanded uncertainty (k = 2) of between 0.02% and 0.05%. The standard diverts a steady flow into a collection tank of known volume during a

Design and Uncertainty Analysis for a PVTt Gas Flow Standard

February 1, 2003
Author(s)
John D. Wright, Aaron N. Johnson, Michael R. Moldover
A new pressure, volume, temperature, and time (PVTt) primary gas flow standard has been constructed at the National Institute of Standards and Technology with an expanded uncertainty of between 0.02 % and 0.05 % (k = 2). The standard covers a flow range of

Error Free Liquid Flow Diverters for Calibration Facilities (FEDSM2002-31085)

January 1, 2002
Author(s)
Tsyh Tyan Yeh, Aaron N. Johnson, Pedro I. Espina, N Yende
A design for diverter valves in gravimetric liquid flow calibration facilities is proposed. The concept makes use of repeated unidirectional motions of the diverter valve to reduce errors associated with asymmetry in the diverter valve motion and in the

Optimization of an Annular Jet Commercial Gas-Metal Atomizer

December 1, 2000
Author(s)
Stephen D. Ridder, Aaron N. Johnson, Pedro I. Espina, Frank S. Biancaniello, G J. DelCorso
The performance of a commercial gas-metal atomizer was studied using a number of previously published research techniques. initially the flow was visualized using schlieren photography to determine the location of important flow features (e.g., shock waves