Vlastnosti dvoufázového toku uvnitř směšovací komory trysky typu effervescent

Characteristics of a Two-phase Flow Inside the Mixing Chamber of an Effervescent Atomizer

conference paper

en

Results of a recent study of the visualization of the two-phase flow inside an aerator of an effervescent atomizer are presented. Effervescent atomization is characterised by bubbling a small amount of gas into the liquid upstream of the exit orifice, thereby forming a two-phase flow. A simplified transparent model of atomizer has been designed in order to observe the two-phase flow of light heating oil and air mixture. High-speed camera Redlake MotionPro was used for visualization. Two-phase flow patterns for specific atomizer operating conditions for vertical downward and horizontal pipe flow were recognised and the mixing processes inside an aerator were described and compared with published two-phase flow maps. The results show that observed two-phase flow patterns are not always in a good agreement with the findings acquired with use of two-phase flow maps. As the effervescent atomizer sprays tend to be unsteady under some operating conditions, a method for mixture unsteadiness measurement was developed and applied. It was based on pressure fluctuation measurement inside the atomizer mixing chamber.

Jsou prezentovány výsledky vizualizace dvoufázového toku uvnitř směšovací komory effervescent trysky. Atomizace effervescent trysek je založena na směšování malého množství plynu s kapalinou před výstupem z trysky. Pro pozorování dvoufázového toku této směsi byl vytvořen zjednodušený model trysky z plexiskla. Pomocí vysokorychlostní kamery bylo detekováno několik specifických režimů dvoufázového toku a porovnáno s výsledky získanými s pomocí publikovaných map dvoufázového toku. Protože typu effervescent mají sklon k tvorbě nestabilního spreje, byla také této problematice věnována pozornost. Byla vytvořena a aplikována vlstní matodika měření nestabilit.

Results of a recent study of the visualization of the two-phase flow inside an aerator of an effervescent atomizer are presented. Effervescent atomization is characterised by bubbling a small amount of gas into the liquid upstream of the exit orifice, thereby forming a two-phase flow. A simplified transparent model of atomizer has been designed in order to observe the two-phase flow of light heating oil and air mixture. High-speed camera Redlake MotionPro was used for visualization. Two-phase flow patterns for specific atomizer operating conditions for vertical downward and horizontal pipe flow were recognised and the mixing processes inside an aerator were described and compared with published two-phase flow maps. The results show that observed two-phase flow patterns are not always in a good agreement with the findings acquired with use of two-phase flow maps. As the effervescent atomizer sprays tend to be unsteady under some operating conditions, a method for mixture unsteadiness measurement was developed and applied. It was based on pressure fluctuation measurement inside the atomizer mixing chamber.

dvoufázový tok, směšovací komora, Effervescent Atomizer

Two-phase Flow, Mixing Chamber, Effervescent Atomizer

2004

01.01.2004

University of Pisa

Pisa

88-467-1075-4

Two-Phase Flow Modelling and Experimentation 2004

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