Discharge coefficient of small sonic nozzles

The purpose of this investigation is to understand flow characteristics in mini/micro sonic nozzles, in order to precisely measure and control miniscule flowrates. Experimental and numerical simulation methods have been used to study critical flow Venturi nozzles. The results show that the nozzle?s size and shape influence gas flow characteristics which leading the boundary layer thickness to change, and then impact on the discharge coefficient. With the diameter of sonic nozzle throat decreasing, the discharge coefficient reduces. The maximum discharge coefficient exits in the condition of the inlet surface radius being double the throat diameter. The longer the diffuser section, the smaller the discharge coefficient becomes. Diffuser angle affects the discharge coefficient slightly.

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Study for the Gas Flow Through a Critical Nozzle

Volume 2: Symposia, Parts A, B, and C ◽

10.1115/fedsm2003-45593 ◽

2003 ◽

Cited By ~ 2

Author(s):

Heuy Dong Kim ◽

Jae Hyung Kim ◽

Kyung Am Park

Keyword(s):

Reynolds Number ◽

Mass Flow ◽

Gas Flow ◽

Critical Pressure ◽

Discharge Coefficient ◽

Pressure Ratio ◽

Nozzle Throat ◽

Critical Nozzle ◽

Flow Through ◽

Diffuser Angle

The critical nozzle is defined as a device to measure the mass flow with only the nozzle supply conditions, making use of flow choking phenomenon at the nozzle throat. The discharge coefficient and critical pressure ratio of the gas flow through the critical nozzle are strongly dependent on Reynolds number, based on the diameter of nozzle throat and nozzle supply conditions. Recently a critical nozzle with small diameter is being extensively used to measure mass flow in a variety of industrial fields. For low Reynolds numbers, prediction of the discharge coefficient and critical pressure is very important since the viscous effects near walls significantly affect the mass flow through critical nozzle, which is associated with working gas consumption and operation conditions of the critical nozzle. In the present study, computational work using the axisymmetric, compressible, Navier-Stokes equations is carried out to predict the discharge coefficient and critical pressure ratio of gas flow through critical nozzle. In order to investigate the effect of the working gas and turbulence model on the discharge coefficient, several kinds of gases and several turbulence models are employed. The Reynolds number effects are investigated with several nozzles with different throat diameter. Diffuser angle is varied to investigate the effects on the discharge coefficient and critical pressure ratio. The computational results are compared with the previous experimental ones. It is known that the standard k-ε turbulence model with the standard wall function gives a best prediction of the discharge coefficient. The discharge coefficient and critical pressure ratio are given by functions of the Reynolds number and boundary layer integral properties. It is also found that diffuser angle affects the critical pressure ratio.

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Computational study of the gas flow through a critical nozzle

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/095440603322517180 ◽

2003 ◽

Vol 217 (10) ◽

pp. 1179-1189 ◽

Cited By ~ 17

Author(s):

H-D Kim ◽

J-H Kim ◽

K-A Park ◽

T Setoguchi ◽

S Matsuo

Keyword(s):

Reynolds Number ◽

Mass Flow ◽

Gas Flow ◽

Critical Pressure ◽

Discharge Coefficient ◽

Pressure Ratio ◽

Nozzle Throat ◽

Critical Nozzle ◽

Flow Through ◽

Diffuser Angle

The critical nozzle is defined as a device to measure the mass flow with only the nozzle supply conditions making use of the flow choking phenomenon at the nozzle throat. The discharge coefficient and critical pressure ratio of the gas flow through the critical nozzle are strongly dependent on the Reynolds number, based on the diameter of the nozzle throat and nozzle supply conditions. Recently a critical nozzle with a small diameter has been extensively used to measure mass flow in a variety of industrial fields. For low Reynolds numbers, prediction of the discharge coefficient and critical pressure is very important since the viscous effects near walls significantly affect the mass flow through the critical nozzle, which is associated with working gas consumption and operation conditions of the critical nozzle. In the present study, computational work using the axisymmetric, compressible, Navier-Stokes equations is carried out to predict the discharge coefficient and critical pressure ratio of gas flow through the critical nozzle. In order to investigate the effect of the working gas and turbulence model on the discharge coefficient, several kinds of gases and several turbulence models are employed. The Reynolds number effects are investigated with several nozzles with different throat diameters. The diffuser angle is varied in order to investigate the effects on the discharge coefficient and critical pressure ratio. The computational results are compared with the previous experimental ones. It is known that the standard k-ε turbulence model with the standard wall function gives the best prediction of the discharge coefficient. The discharge coefficient and critical pressure ratio are given by functions of the Reynolds number and boundary layer integral properties. It is also found that the diffuser angle affects the critical pressure ratio.

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Gravimetric Calibration of Critical Flow Venturi Nozzles

Volume 1 ◽

10.1115/ht-fed2004-56817 ◽

2004 ◽

Cited By ~ 1

Author(s):

Thomas B. Morrow

Keyword(s):

Natural Gas ◽

Gas Flow ◽

Discharge Coefficient ◽

Computer Code ◽

Critical Flow ◽

Calibration Data ◽

Sonic Nozzle ◽

Flow Meters ◽

Southwest Research Institute ◽

Layer Flow

The Metering Research Facility (MRF) was commissioned in 1995/1996 at Southwest Research Institute for research on, and calibration of natural gas flow meters. A key commissioning activity was the calibration of critical flow Venturi (sonic) nozzles by a gravimetric proving process flowing nitrogen or natural gas at different pressures. This paper concerns the calibration of the four sonic nozzles installed in the MRF Low Pressure Loop (LPL). Recently, a new project prompted a review of the relations used to calculate sonic nozzle discharge coefficient in the LPL data acquisition computer code. New calibrations of the LPL sonic nozzles were performed flowing natural gas over a lower range of pressure than used in the original commissioning tests. The combination of new and old gravimetric calibration data are shown to agree well with correlations published by Arnberg and Ishibashi (2001) and by Ishibashi and Takamoto (2001) for laminar, transitional and turbulent boundary layer flow in critical flow Venturi nozzles.

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Collapse Evolvement Analysis of Upstream Tailings Dam in Flood Situation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.212-213.759 ◽

2012 ◽

Vol 212-213 ◽

pp. 759-764

Author(s):

Xiao Fei Jing ◽

Wei Zhong Zhang ◽

Yu Long Chen ◽

Zhi Yong Cai

Keyword(s):

Rural Areas ◽

Flood Hazard ◽

Industrial Processes ◽

Simulation Methods ◽

Tailings Dam ◽

Collapse Mode ◽

Wide Range ◽

Numerical Simulation Methods ◽

And Control ◽

Important Significance

Very large volume of mined ore materials are processed annually to obtain the various types of minerals that are essential to industrial processes, the upstream tailings dam is usually constructed to store these wastes. But with the increasing of dam quantities, the tailings dam collapsing in flood which are among the most dangerous hazards that affect mountainous and rural areas in a wide range of environments become more and more. Therefore it’s necessary to analyze the collapse mode of upstream tailings dam in flood situation. This paper using the physical model experiment and numerical simulation methods to research on the displacement, saturation line, stress and the broken processes, and the collapse mode of upstream tailings dam in flood water encountered in 100 years are explored. The results have very important significance and scientific support to understand the mechanism of collapse and broken mode deeply, and which have any new exploration for the prevention and control in flood hazard.

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