Discussion on Flow-Through Phenomena in the Air Gauge Cascade

Abstract

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.

Recent Development of Air Gauging in Industry 4.0 Context

“…When projecting and using air gauges, it is necessary to take into consideration main properties of the compressed air, thermodynamic processes, and some laws of the fluid mechanics in respect of the geometry of the flow-through components [ 58 ]. Jermak [ 59 ] undertook a discussion on the complex phenomena pointing out the supersonic areas and appearance of a vacuum ring in the flapper-nozzle area, which caused discontinuity and hysteresis in the metrological characteristics. The author analyzed also the expansion of compressed air stream in the measuring chamber, right after the inlet nozzle.…”

Dynamics of in-process control with non-contact air gauges

“…After some decline in the development, air gauges regained new attention (Schuetz, 2008;Koenig 2017), especially in the context of the in-process control (Menzies & Koshy, 2009;Vacharanukul & Mekid, 2005;Koehn 2015;Rao 2017). In particular, researchers looked for the ways of improvement of static and dynamic characteristics of the air gauges (Jermak 2010;Cellary & Jermak 1997;Jakubowicz & Derezynski 2017), proposed some modifications of the nozzle geometry (Jakubowicz 2020), and evaluated new models of their (Bokov 2011;Jermak 2017). However, dynamical properties of an air gauge are considered rather poor, e.g.…”