Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics

Characterisation of inhalation aerosols focuses in the first instance on aerodynamic particle size, which is measured using cascade impactors. The aerosol must contain large quantities of particles in the respirable size range 1-5 m. Deposition on impactor stages depends on the velocity of the part...

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Main Authors:	Hendrik Versteeg, Graham Hargrave, Ben Myatt, David Lewis, Tanya Church, G. Brambilla
Format:	Default Conference proceeding
Published:	2017
Subjects:	Mechanical engineering not elsewhere classified Metered dose inhalers (MDIs) Aerosol plume dynamics Phase-Doppler anemometry (PDA) High-speed imaging and particle image velocimetry (PIV) Mechanical Engineering not elsewhere classified
Online Access:	https://hdl.handle.net/2134/24258
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id	rr-article-9558845
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spelling	rr-article-95588452017-01-01T00:00:00Z Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics Hendrik Versteeg (1248945) Graham Hargrave (1258908) Ben Myatt (1257927) David Lewis (245511) Tanya Church (7210106) G. Brambilla (3705427) Mechanical engineering not elsewhere classified Metered dose inhalers (MDIs) Aerosol plume dynamics Phase-Doppler anemometry (PDA) High-speed imaging and particle image velocimetry (PIV) Mechanical Engineering not elsewhere classified Characterisation of inhalation aerosols focuses in the first instance on aerodynamic particle size, which is measured using cascade impactors. The aerosol must contain large quantities of particles in the respirable size range 1-5 m. Deposition on impactor stages depends on the velocity of the particles as well as their size. Pressurised metered dose inhalers (pMDIs) produce very fast-moving spray plumes, so it is important to understand the dynamic nature of droplet formation processes and spray plumes. This paper presents a selection of findings from an optical diagnostics study of aerosol plumes generated by a Bespak 630 series actuator in conjunction with a series of HFA134a placebo formulations containing ethanol up to 20% w/w. Spray plume dynamics in the vicinity of the spray orifice and further downstream were characterised using phase-Doppler anemometry (PDA), high-speed imaging and particle image velocimetry (PIV). The findings of the work demonstrate the complementary capabilities of these instruments. PDA provides simultaneous values of mean droplet size and velocity (and their associated statistics), but it is time-consuming to sample a sufficient number of locations to characterise the rapidly changing spray plume. PIV, on the other hand, provides information on entire flow fields albeit at lower spatial and temporal resolution. PIV and PDA data for the velocity of various spray plumes were found to be in good agreement, which validates both techniques. High-speed imaging also captures the overall characteristics of the plume. The diffraction limit of the optical configuration used for imaging is around 10 m, so it is not possible to observe respirable droplets individually. However, the dynamics and trajectories of larger droplets can be studied. These larger droplets were found to be produced by highly localised atomisation processes, so the resulting droplets can be easily missed or undersampled in PDA surveys. These results suggest that further research on pMDI sprays with these combined tools will provide useful insights into the processes responsible for changes in droplet size and velocity, and can be expected to make a major contribution to improving the development of the next generation of pMDI inhalers. 2017-01-01T00:00:00Z Text Conference contribution 2134/24258 https://figshare.com/articles/conference_contribution/Using_phase_Doppler_anemometry_high_speed_imaging_to_analyze_MDI_spray_plume_dynamics/9558845 CC BY-NC-ND 4.0
institution	Loughborough University
collection	Figshare
topic	Mechanical engineering not elsewhere classified Metered dose inhalers (MDIs) Aerosol plume dynamics Phase-Doppler anemometry (PDA) High-speed imaging and particle image velocimetry (PIV) Mechanical Engineering not elsewhere classified
spellingShingle	Mechanical engineering not elsewhere classified Metered dose inhalers (MDIs) Aerosol plume dynamics Phase-Doppler anemometry (PDA) High-speed imaging and particle image velocimetry (PIV) Mechanical Engineering not elsewhere classified Hendrik Versteeg Graham Hargrave Ben Myatt David Lewis Tanya Church G. Brambilla Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics
description	Characterisation of inhalation aerosols focuses in the first instance on aerodynamic particle size, which is measured using cascade impactors. The aerosol must contain large quantities of particles in the respirable size range 1-5 m. Deposition on impactor stages depends on the velocity of the particles as well as their size. Pressurised metered dose inhalers (pMDIs) produce very fast-moving spray plumes, so it is important to understand the dynamic nature of droplet formation processes and spray plumes. This paper presents a selection of findings from an optical diagnostics study of aerosol plumes generated by a Bespak 630 series actuator in conjunction with a series of HFA134a placebo formulations containing ethanol up to 20% w/w. Spray plume dynamics in the vicinity of the spray orifice and further downstream were characterised using phase-Doppler anemometry (PDA), high-speed imaging and particle image velocimetry (PIV). The findings of the work demonstrate the complementary capabilities of these instruments. PDA provides simultaneous values of mean droplet size and velocity (and their associated statistics), but it is time-consuming to sample a sufficient number of locations to characterise the rapidly changing spray plume. PIV, on the other hand, provides information on entire flow fields albeit at lower spatial and temporal resolution. PIV and PDA data for the velocity of various spray plumes were found to be in good agreement, which validates both techniques. High-speed imaging also captures the overall characteristics of the plume. The diffraction limit of the optical configuration used for imaging is around 10 m, so it is not possible to observe respirable droplets individually. However, the dynamics and trajectories of larger droplets can be studied. These larger droplets were found to be produced by highly localised atomisation processes, so the resulting droplets can be easily missed or undersampled in PDA surveys. These results suggest that further research on pMDI sprays with these combined tools will provide useful insights into the processes responsible for changes in droplet size and velocity, and can be expected to make a major contribution to improving the development of the next generation of pMDI inhalers.
format	Default Conference proceeding
author	Hendrik Versteeg Graham Hargrave Ben Myatt David Lewis Tanya Church G. Brambilla
author_facet	Hendrik Versteeg Graham Hargrave Ben Myatt David Lewis Tanya Church G. Brambilla
author_sort	Hendrik Versteeg (1248945)
title	Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics
title_short	Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics
title_full	Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics
title_fullStr	Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics
title_full_unstemmed	Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics
title_sort	using phase doppler anemometry & high speed imaging to analyze mdi spray plume dynamics
publishDate	2017
url	https://hdl.handle.net/2134/24258
_version_	1797556211283918848

Using phase Doppler anemometry & high speed imaging to analyze MDI spray plume dynamics

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