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LTI     The Low Turbulence Inlet - Design


CONCEPT    FUNCTION    MODELING    RESULTS

Instrumentation:

The inlet is instrumented so that the suction mass flow, the sample mass flow, the static pressure at the inlet tip, the pressure drop from front to rear of the diffuser and the turbulence intensity at the exit of the porous diffuser is measured. A pitot-static tube is deployed near the inlet so that the local air speed is known. This value is used by the system that controls the suction flow so that the inlet samples isokinetically.

LTI Flow and Control System Schematic From TexAQS 2000 Campaign

Flow Control:


Sample Flow Control:

The control system maintains isokinetic flow at the inlet entrance without user supervision.  Computer controlled valves regulate both the suction and the sample flows.  The sample flow is input by the user and the software and electronics adjust the suction flow to compensate for variations in the sample flow and in the aircraft’s true airspeed and altitude.  The sample flow may also be regulated by an aerosol characterizing instrument that has an internal flow controller.

Porous Material Blockage from Extended Use:


Shown above are periodic flow calibrations of a diffuser. The porous material traps ambient aerosol causing pore blockage.  Thus, the pressure drop as a function of flow rate through the material increases with time.  The PELTI experiment comprised twelve flights predominately in the marine boundary layer and produced an 8.5% increase in the porous material pressure drop.  The TexAQS2000 deployment comprised twelve flights predominately in the boundary layer over Texas and produced another 11% increase.  The porous material was agitated in an ultrasonic cleaner with a mild detergent and produced a 4% pressure drop reduction.  Improvements in cleaning techniques are presently being developed.

SolidWorks LTI

SolidWorks LTI Section

LTI Major Dimensions

 

  Updated August 9, 2011

Contact: jwilson@du.edu