Inlet Systems
Inlet systems – Multipurpose inlet systems for airborene atmospheric research
Universal Inlet (UNI)
For airborne gas phase measurements an inlet system has been developed, which gives the opportunity to take atmospheric samples both in and against flight direction. The two main 12 mm dia. stainless-steel tubes can be used to host any chemically inert tubing material (e.g. PTFE). Optionally a third steel tube (6 mm dia.) can be installed. All front areas of the inlet system are heated to facilitate flights under icing conditions. The rear foot cover is removeable for maintenance purposes.
This inlet system has been used on top of the fuselage of a Do 128, D-IBUF and on a window of a Learjet 35 A, D-CGFD.
Isokinetic Whole Air Inlet System (IWAIS)
For airborne gas phase measurements an inlet system has been developped which was adapted for the first time to an Iljuschin Il-18. This inlet system prevents contamination during take off or landing and allows chemically inert measurements in the gas phase even while passing through clouds.
The IWAIS is based on the impactor principle. Whole air enters the round inlet, passes a diffuser, and flows through a round jet impactor. While the smaller droplets or particles can follow the stream-lines of the air the bigger ones impact on the impaction plate. By using a classical impaction stage design the cut-off diameter can be accurately predicted by applying the design criteria of Marple and Willeke, 1976* which are numerically developed and experimentally proven.
This inlet system has been used for airborne measurements aboard Iljuschin Il-18 and in a modified version aboard Partenavia P68B D-GERY.
A similiar design named ICPSrj (Isokinetic Cloud Probing System (round jet)) was used for ground-based measurements within the EC-project CIME. The system, operated by IfT (Institute for Tropospheric Research, Leipzig), was used in the wind-tunnel facility at Mt. Puy de D�me, France to perform gas-phase and aerosol measurements in the size range of the interstitial aerosol.
CVI-Inlet Systems
The “Counterflow Virtual Impactor (CVI)” technique for aerosol measurements is well proved but it is still a challenging task to design airborne CVI inlet systems. Meanwhile enviscope designed different types:
One system is utilized on the Partenavia P68 D-GERY on behalf of the Institute for Tropospheric Research. Since the flow field at the CVI tip is critical, the complete system was built up in a flow tube upon the aircraft.
Another CVI Inlet was designed for the new research aircraft ATR42 on behalf of the Centre National de la Recherche Scientifique (France),
The development was done in an interactive joint venture with Université Blaise Pascal, Laboratoire de Météorologie Physique to create a state-of-the-art inlet system for dry aerosol particle probing. Multiple scientific and technical demands as well as a layout based on airworthiness standards had to be considered.
The allegation of a highly adaptable design to different flow velocities and applications was fulfilled by an axial adjustable and changeable shroud.
enviscope was responsible for the detailed 3D design based on flow calculations, manufactured the system in cooperation with skilled partners, and compiled the complete documentation including Load Analysis, Stress Report and Drawings for the certification process.
Different types of probing systems
A variety of different air intake systems for bulk air samples, cloud water, ice or aerosol probing has been developed in the past.
Today enviscope can acquire from a long experience to create new customized air probing systems for future research projects.
*Reference: Marple, V.A., K. Willeke, 1976: Inertial impactors: Theory, design and use, in Benjamin Y.H. Liu (ed.), Fine particles — aerosol generation, measurement, sampling, and analysis, Academic Press, 411-445.