Operational Status (select from or add to list):
requestable, ready for deployment
General Description (with photos, diagrams, etc.):
- The Solid Diffuser Inlet (SDI) is an air sample inlet for aerosol instruments located in the fuselage of the C-130. It is a clone of University of Hawaii SDI that was designed to create iso-kinetic flow conditions at the inlet tip to minimize loss of aerosol particles during passage from the atmosphere into the aircraft cabin for sampling. It is a forward-facing diffuser inlet with a sharp tip. Suction is provided by a blower inside the aircraft. The total volume flow is measured and adjusted with a valve in order to obtain iso-kinetic flow (velocity at the inlet tip equals flight speed). Three SDI systems are available. They have inlet diameters 4.4 mm,5.9 mm and 5.4 mm (Clarke inlet).
- The photo above shows the SDI inlet mounted on right side of C-130 fuselage, providing air samples to several instruments inside the aircraft. Inlets points into the direction of flight.
- The variation of the SDI shown above has a flow alignment shroud. The Clarke inlet was developed by Tony Clarke (Univ Hawaii) and a copy was made for the C-130. For more information, see documentation link below.
- The hole at the inlet tip is ~5 mm ID and the diffusing cone expands to 38 mm in order to reduce the average velocity by a factor ~60. The cone half-angle is only 4.4 deg, which prevents internal flow separation and re-circulations.
- Edges of the tip are precision machined to have an elliptical cross section shape. This shape reduces the tendency that sharp-edge inlets have for flow separation when the flow is not aligned with the inlet axis.
Measurement Characteristics: Avoids relative size-sorting of aerosol particles by using iso-kinetic flow though inlet tip