Methods to calibrate a critical nozzle and flowmeter using reference critical nozzles

The paper describes primary calibration of high-precision nozzles (HPNs), which have ideal geometries, at critical condition, theoretical calculation of the discharge coefficient to be verified by the primary calibration, concept of fluid dynamical standard using HPN, precise measurement of boundary layer transition in HPNs in terms of flowrate, superfine structure in the critical flowrate, discrepancy which can occur between primary calibrations and field applications of critical nozzles, and 3D flow velocity field measurements based on recovery temperature, which visualizes many interesting phenomena in axi-symmetric transonic flow as shock interactions, acceleration by edge, reflection of shocks, Fano flow and so on.

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Numerical Study on Characteristics of Real Gas Flow Through a Critical Nozzle

International Journal of Turbo and Jet Engines ◽

10.1515/tjj-2012-0004 ◽

2012 ◽

Vol 29 (1) ◽

Cited By ~ 7

Author(s):

Junji Nagao ◽

Shigeru Matsuo ◽

Mamun Mohammad ◽

Toshiaki Setoguchi ◽

Heuy Dong Kim

Keyword(s):

Gas Flow ◽

Numerical Study ◽

Real Gas ◽

Critical Nozzle ◽

Flow Through

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Research on collaborative control of double-plunger gas prover based on EtherCAT

Thermal Science ◽

10.2298/tsci191022002x ◽

2020 ◽

Vol 24 (5 Part A) ◽

pp. 2667-2687

Author(s):

Zhipeng Xu ◽

Feipeng Xu ◽

Dailiang Xie

Keyword(s):

Flow Rate ◽

High Speed ◽

Gas Flow ◽

Control Unit ◽

External Diameter ◽

Piston Cylinder ◽

Collaborative Control ◽

Critical Nozzles ◽

Parallel Mode ◽

Working Principle

Piston prover has been widely used as a gas flow standard for its advantages of high accuracy in standard volume, flow stability and repeatability. It has also been employed as the primary gas flow standard in many countries to calibrate meters. However, it is difficult to ensure the uniformity of the inside dimension of the piston, thus the application of conventional piston provers are limited by the maximum calibration flow generated by the piston cylinder volume. In this paper, an improved piston gas prover that mainly consists of two uniform plungers was proposed. Their external diameter constitutes the flow standard. The plungers are driven by servo motor, and the high speed fieldbus EtherCAT has been introduced as the control unit. Hence the two pistons could work collaboratively and operate in three modes: single-piston mode, double-pistons parallel mode, and double-pistons reciprocating mode. Besides generating steady-flow rate, the double-plunger prover can even produce an unsteady-flow rate which could be used to research the dynamic characteristics of flow meters. The structure and working principle of the three modes were carefully introduced. Then experiments for calibrating critical nozzles were carried out, and the results show that the repeatability of the discharge coefficient could be better than 0.06%, and the pressure fluctuation during the process was less than 50 Pa.

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Calibration of Critical Nozzles Against Another One Connected in Series and Its Application

Transactions of the Society of Instrument and Control Engineers ◽

10.9746/sicetr1965.34.698 ◽

1998 ◽

Vol 34 (7) ◽

pp. 698-706

Author(s):

Masahiro ISHIBASHI ◽

Masaki TAKAMOTO ◽

Yu-ichi NAKAO ◽

Toshio YOKOMIZO

Keyword(s):

Critical Nozzles ◽

In Series

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pRTA (Probe Recovery Temperature Anemometry)

Volume 1 ◽

10.1115/ht-fed2004-56806 ◽

2004 ◽

Cited By ~ 1

Author(s):

Masahiro Ishibashi

Keyword(s):

Prandtl Number ◽

Flow Velocity ◽

Contact Point ◽

Recovery Factor ◽

Angle Of Incidence ◽

Square Root ◽

Critical Nozzle ◽

Axis Of Symmetry ◽

Thermocouple Wire ◽

Recovery Temperature

It is shown that the recovery temperature measured by a thin thermocouple wire inserted in airflow does not depend on the angle of incidence of the flow onto the wire and agrees very well with the theoretical value assuming the recovery factor of the square root of the Prandtl number. This fact allows RTA (Recovery Temperature Anemometry) employing a sensor of various structures; pRTA (probe RTA) is one of the examples where the thermocouple wire is bent at its contact point forming the probe apex. The paper demonstrates that pRTA measures the same flow velocity distributions in a critical nozzle as those by sRTA (streamwise RTA) where a thermocouple wire is settled parallel to the axis of symmetry of the nozzle.

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The effect of diffuser angle on the discharge coefficient of a miniature critical nozzle

Journal of Thermal Science ◽

10.1007/s11630-010-0222-2 ◽

2010 ◽

Vol 19 (3) ◽

pp. 222-227 ◽

Cited By ~ 4

Author(s):

Jae Hyung Kim ◽

Heuy Dong Kim ◽

Toshiaki Setoguchi

Keyword(s):

Discharge Coefficient ◽

Critical Nozzle ◽

Diffuser Angle

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G1003 Characteristic Evaluation of Critical Nozzle Flow Meter in High Reynolds Number Area

The Proceedings of the Fluids engineering conference ◽

10.1299/jsmefed.2013._g1003-01_ ◽

2013 ◽

Vol 2013 (0) ◽

pp. _G1003-01_-_G1003-02_

Author(s):

Toshihiro MORIOKA

Keyword(s):

Reynolds Number ◽

High Reynolds Number ◽

Nozzle Flow ◽

Flow Meter ◽

Critical Nozzle ◽

High Reynolds

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Review of Critical Flowmeters for Gas Flow Measurements

Journal of Basic Engineering ◽

10.1115/1.3658664 ◽

1962 ◽

Vol 84 (4) ◽

pp. 447-457 ◽

Cited By ~ 23

Author(s):

B. T. Arnberg

Keyword(s):

Mass Flow ◽

Flow Measurement ◽

Gas Flow ◽

Flow Measurements ◽

Flow Rates ◽

Real Gas ◽

Discharge Coefficients ◽

Critical Nozzles ◽

Mass Flow Rates ◽

Flow Functions

Critical flowmeters for accurately measuring the mass flow rates of nonreacting real gases were reviewed. Discussions were presented on theoretical flow functions, on parameters for correlating discharge coefficients, and on the importance of real gas properties. The performance characteristics of critical nozzles and orifices of several designs were reviewed. Approaches were discussed to problems which must be researched before the fullest potential of this type of flow measurement can be realized.

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