New projects and teams have been set up at the beginning of 2015. These have been updated following a 2018 review. Below is a list of projects selected. Projects are either in their infancy due to the new organisation of work in the Impactor Sub Group or work is being consolidated from previous work to generate a more refined objective and plan for the future.
NM provided an update at work conducted at Vectura to support Darryl’s investigations, and provided an industry perspective on using ΔP measurements for in-use impactor monitoring.
Vectura are currently gathering data on their in-use NGI’s to determine whether the ΔP measurements are sensitive enough to detect atypical impactor results. They are currently awaiting mensuration of the uncleaned NGI to determine correlation of ΔP with changes in nozzle diameter.
The presentation raised the following observations:
MC/DR commented that the issue of whether impactor manufacturing tolerance limits were appropriate for in-use limits. If these could be widened would ΔP be more useful?
The group took an action to gather more information regarding which devices are in use, with a view to designing a more specific questionnaire to gauge wealth of available data, and to consider circulating the questionnaire to users outside of the impactor group (Copley may be able to help with this if we decide to explore this option). The group should also consider whether a new workshop (perhaps at a future DDL?) would be useful to present new data to a wider audience.
Modelling of particle deposition – HV reported that Steady flow model reveals complex flow distribution in single nozzle impactor and that Collection efficiency curves can be matched to data by adjusting models of turbulence and particle restitution behaviour.
Four options for future work were presented, of these option 3 – Study effect of low, medium and high resistance on transient flow through cascade impactors – was preferred.