The Influence of the Regulator Diameter and Injection Nozzle Geometry on the Flow Structure in Pneumatic Dimensional Control Systems

Crnojevic, C.; Roy, G.; Bettahar, A.; Florent, P.

doi:10.1115/1.2819288

Cited by 20 publications

(13 citation statements)

References 1 publication

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“…This basically translates into a vena contracta effect at the entrance of the space between the nozzle and the flat plate. This general behaviour corresponds with the results found in the experimental work by [5]. Clearly, this separated flow area is the probable cause of fouling in industrial applications.…”

Section: Resultssupporting

confidence: 87%

A numerical analysis of turbulent compressible radial channel flow with particular reference to pneumatic controllers

2004

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A numerical analysis of turbulent axisymmetric radial compressible channel flow between a nozzle and a flat plate is presented in this paper. In particular, the application of this type of flow situation in pneumatic dimensional control systems is considered. The Spalart-Allmaras one-equation turbulence model is used. The resulting highly coupled PDE system has been solved using the control volume based numerical approach where the power-law scheme was used extensively to compute the diffusive and convective fluxes of momentum. Results show that local Mach numbers can easily achieve and surpass unity for typical industrial configurations. Also, in the case of a standard industrial nozzle geometry, the presence of a toroidal recirculation zone that moves radially outward is clearly identified in most cases. Separated flow areas are of particular concern as it has been shown previously that they can cause nozzle fouling in industrial applications. It has been shown that the size of this region is dependant on feed pressure. Considerable differences between results obtained using the Spalart-Allmaras and standard k-~ turbulence models have also been noticed.

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Section: Resultssupporting

confidence: 87%

A numerical analysis of turbulent compressible radial channel flow with particular reference to pneumatic controllers

2004

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“…The authors (Crnojevic et al, 1997) suggested that the discontinuity was caused by the diagonal strike wave that appeared in the outlet area of the measuring nozzle close to the flapper surface. As a result, the pressure losses increased and hence the airflow decreased.…”

Section: Discussion On the Discontinuity Of The Air Gauges Characterimentioning

confidence: 99%

“…1. It consists of inlet nozzle or restriction (1), measuring chamber (2) and measuring nozzle (3). Sometimes the measuring head may contain two or more measuring nozzles of equal geometry and dimensions.…”

Section: Air Gauging Principlementioning

confidence: 99%

Discussion on Flow-Through Phenomena in the Air Gauge Cascade

Jermak

2017

Acta Mechanica Et Automatica

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Abstract:In the paper, the flow-through phenomena in the air gauge are under discussion form the thermodynamic and gasodynamic perspective. The main elements of the cascade are considered the inlet nozzle (restriction), measuring chamber and the measuring nozzle with the measuring slot (displacement between the nozzle head and measured surface). The purpose of the analysis was to point out the impact on the metrological characteristics of the air gauge. In particular, attention was paid to the airflow through the measuring slot. Here, the complex phenomena take place, among others the supersonic areas and a "bubble ring," which cause discontinuity and hysteresis in the static characteristic. On the other hand, the air stream expansion after the restriction (inlet nozzle) is observed in the measuring chamber. The point of the above discussion was to work out some recommendation on the nozzles geometry and the localization of the back-pressure measuring point in the chamber.

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“…Although some improvement could be made [27] on the curve function = ( ) to prolong its proportional (linear) range, the problem stays basically the same: in a wider range the linearity of the functions gets worse. An additional problem is the need of adjustment any time the jet plug (measuring head) is changed to perform a different measuring task.…”

Section: Discussionmentioning

confidence: 99%

Air Gauge Characteristics Linearity Improvement

Jermak

Jakubowicz

Dereżyński

et al. 2016

Journal of Control Science and Engineering

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This paper discusses calibration uncertainty and linearity issues of the typical back-pressure air gauge. In this sort of air gauge, the correlation between the measured dimension (represented by the slot width) and the air pressure in the measuring chamber is used in a proportional range. However, when high linearity is required (e.g., nonlinearity less than 1%), the measuring range should be shortened. In the proposed method, based on knowledge of the static characteristics of air gauges, the measuring range is kept unchanged but the nonlinearity is decreased. The static characteristics may be separated into two sections, each of them approximated with a different linear function. As a result, the nonlinearity is reduced from 5% down to 1% and even below.

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The Influence of the Regulator Diameter and Injection Nozzle Geometry on the Flow Structure in Pneumatic Dimensional Control Systems

Cited by 20 publications

References 1 publication

A numerical analysis of turbulent compressible radial channel flow with particular reference to pneumatic controllers

A numerical analysis of turbulent compressible radial channel flow with particular reference to pneumatic controllers

Discussion on Flow-Through Phenomena in the Air Gauge Cascade

Air Gauge Characteristics Linearity Improvement

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