Institute for Climate and Atmospheric Science School of Earth and Environment Low Turbulence Inlet Mark Bart University of Leeds Chuck Wilson Trevor Kroeger University of Denver Jamie Trembath FAAM e

LTI concept Due to high airspeed, traditional aircraft aerosol sampling suffers from several problems including matched isokinetic sample flow and turbulent deposition. The low turbulence inlet attempts to bypass these problems by actively pumping the turbulent boundary layer through a porous diffuser at the inlet, thus slowing the sample down and encouraging laminar flow. Institute for Climate and Atmospheric Science School of Earth and Environment

LTI History The LTI was originally developed at the University of Denver by Wilson et al1 for use on the NCAR Electra. It has since been moved to the NCAR C-130. The LTI for the FAAM 146 was also developed by Chuck Wilson et al and was part of the original 146 instrument specification. It has flown 122 hours and 27 missions during DABEX and DODO Funding was secured for an LTI hardware upgrade as part of the Fennec campaign. 1. Wilson et al. Function and Performance of a Low Turbulence Inlet for Sampling Supermicron Particles from Aircraft Platforms, Aerosol Sci. Tech. 38, 790–802, (2004) Institute for Climate and Atmospheric Science School of Earth and Environment

LTI Upgrade New computer system installed and upgraded – this took quite a bit of work Now runs simple LabView client. All sensors calibrated and tested During August I reinstalled the hardware and had Chuck Wilson over to help out with his student Trevor Kroeger and a postdoc Duncan Axisa (who was on his way to India) We had 2 successful test flights…. Institute for Climate and Atmospheric Science School of Earth and Environment

Test flights Isokinetic? Turbulence All within operating envelope The turbulent part is at 100 feet. Question: Is boundary layer turbulence propagating through inlet? Institute for Climate and Atmospheric Science School of Earth and Environment

Photos Institute for Climate and Atmospheric Science School of Earth and Environment

What next? LTI is fundamentally robust at getting a direct iso-kinetic aerosol sample The design is very good with multiple redundancies. Jamie’s inlet tests have confirmed that there is a need for a characterised inlet so lets not waste it. We are working on getting a Grimm fitted near LTI inlet. This will involve a re-design some of the LTI plumbing near where the front where the sample comes through the aircraft skin. Filters for Fennec pilot – no sizing instrument which limits the use of the LTI somewhat for concentration/enhancement measurements. Also the LTI is a bit wasted on filters alone. It is a sophisticated inlet. There is no point in using it for bulk filter sampling alone. What about the CCI? What about the noisy pump? Institute for Climate and Atmospheric Science School of Earth and Environment

VACC VACC hasn’t seen much action since last year. Jen has done a load of work getting the software upgraded. Unsure where to go from here with it in the long term. It needs a substantial amount of money invested. We have seen from VOCALS however that it can be a useful instrument. Comments please. Institute for Climate and Atmospheric Science School of Earth and Environment