Porovnání dvoufázového proudění vzduch - částice v realistickém a zjednodušeném modelu lidských plic

COMPARISON OF PARTICLE-LADEN AIR FLOW IN REALISTIC AND SEMI-REALISTIC MODEL OF HUMAN AIRWAYS

abstrakt

en

We have developed a new human airway model as a simplified version of a model with realistic ge-ometry with the aim to improve optical access for laser based airflow measurements. Time-resolved cyclic flow velocities in both the models were com-pared. Identical general features of the flow with some important differences were found. Particularly the velocity fluctuations, attributed to Dean flow and to Taylor-Görtler vortices in the realistic model, were suppressed in the simple-shape model. The latter, by contrast, provides several fold higher sampling rate and superior data acquired by Phase-Doppler Anemometry (PDA) due to better optical access. It predetermines this model for validation of CFD predictions having in mind that it cannot fully resolve the character of the real flow. Despite of this a more detailed flow study in the simplified model has shown a spatial complexity of the flow in bifur-cating model. Inspiratory turbulence, due to the lar-yngeal jet, as well as the expiratory mixing driven turbulence were documented. Particle clustering was found and attributed to the mixing from main stem bronchi.

V příspěvku je provedeno porovnání proudění vzduchu s částicemi mikronové velikosti v realistickém a zjednodušeném modelu plic. Byl použit průhledný realistický model dýchacích cest člověka s nesymetrickým větvením a prostorovou geometrií obsahující části od hrdla až třetí-čtvrté generace bronchů a odpovídající zjednodušený model. Pro studium rychlosti proudění byla použita fázová dopplerovská anemometrie.

We have developed a new human airway model as a simplified version of a model with realistic ge-ometry with the aim to improve optical access for laser based airflow measurements. Time-resolved cyclic flow velocities in both the models were com-pared. Identical general features of the flow with some important differences were found. Particularly the velocity fluctuations, attributed to Dean flow and to Taylor-Görtler vortices in the realistic model, were suppressed in the simple-shape model. The latter, by contrast, provides several fold higher sampling rate and superior data acquired by Phase-Doppler Anemometry (PDA) due to better optical access. It predetermines this model for validation of CFD predictions having in mind that it cannot fully resolve the character of the real flow. Despite of this a more detailed flow study in the simplified model has shown a spatial complexity of the flow in bifur-cating model. Inspiratory turbulence, due to the lar-yngeal jet, as well as the expiratory mixing driven turbulence were documented. Particle clustering was found and attributed to the mixing from main stem bronchi.

dvoufázové proudění, vzduch – částice, realistický model, lidské plíce

PARTICLE-LADEN AIR FLOW, REALISTIC MODEL, HUMAN AIRWAYS

07.06.2012

European Research Community on Flow Turbulence and Combustion

Thessaloniki, Greece.

9th International ERCOFTAC Symposium on Engineering Turbulence Modeling and Measurements

1–6

6