Instrument Information
IDENTIFIER urn:nasa:pds:context:instrument:pal.twt::1.0
NAME TITAN WIND TUNNEL
TYPE ATMOSPHERIC SCIENCES
DESCRIPTION
One of several wind tunnels operated by Arizona State University at the Planetary Aeolian Laboratory at NASA Ames Research 
Laboratory, Moffett Field, CA, Building N242. 
          
The Titan Wind Tunnel (historically, the Venus Wind Tunnel) is a closed circuit wind tunnel with a test section of 20 cm 
(8 in) in diameter and 122 cm (48 in) long. It has been designed to allow the removal of the test section from the tunnel
circuit for access to the test area. Test plates can be substituted, instrumentation and media can be prepared for test
runs, and final inspection of bed forms can be documented at the end of a test run. The floor plate installed properly,
rests against the curved walls of the test section, level, approximately one third of the diameter distance above the 
bottom of the test section pipe segment. There are four vieweing ports and one instrument port in the test section. One
viewing port is located 30 cm (12 in) from the upwind end to the center of the 7.6 cm (3 in) diameter viewing port, 
oriented facing out from the center of the tunnel circuit. The other three viewing ports are located 30 cm (12 in) from 
the downwind end of the test section, providing a view from above. The diameter of this viewing port is 5 cm (2 in). The
other two viewing ports are located on the sides of the test section opposite each other. They are also 7.6 cm (3 in)
diameter. All viewing port centers match the center of the test section. All viewing port windows are Type W Safety Glass
installed in lens horler assemblies (with gaskets) designed to withstand 600 psi pressure. The instrument port was added
in 2010 to accomodate redesigned data collection equipment. It is located on the bottom of the test section at 61 cm 
(24 in). A machined stainless steel plug is fitted to the port assembly, allowing for air line connections to a traversing
pitot tube mechanism and electrical wiring for control of the traversing pito and data collection from the test section.
Another pitot tube is located in the straight section of the tunnel circuit, opposite the removable test section in a 
permanently fixed position in the center of the pipe to measure freestream wind sppeds. Both pitot tubes are plumbed 
to a switch that directs which location measurements are being taken from. A custom designed differential pressure 
transducer (manufactured by Tavis Corporation) is connected to the switch.

The tunnel is powered by a 1.5 hp D.C. variable speed motor which drives an eight bladed fan. The manipulation of gas
flow within the tunnel is constructed of schedule 80, steel pipe. Originally pressure tested to 67 bar, the most recent
certification was for pressures up to 20 bar. Modifications implemented for the Titan project include two revised
pressurization methods: 
  
  In one system, pressurization is achieved by accessing the compressed air supply of building N242. The source of the
  compressed air is an electrically powered air compressor manufactured by Atlas Copco in 2004, model GA55C. It is a 
  75 hp unit with a maximum output pressure of 183 psi. The pressurized air passes through a heatless desiccant dryer
  manufactured by the Airtek Corporation. The twin tower unit is a model TW250 with a drying standard of "dew point at 
  -40 degrees". The compressed air from this system is stored in a 30 thousand gallon tank, before being delivered 
  inside the building. The delivery pressure varies from 150-165 psi. If the delivery pressure is insufficient for the
  planned testing, a 2:1 air amplifier manufactured by Interface Devices, Inc. can be utilized to increase the tunnel
  pressure to the desired level.
  
  The other pressurization option accesses a compressed gas cylinder system. This system consists of eight "K bottle"
  cylinders mounted to a rack assembly with separate valves and regulators for each cylinder, connected by a pressure
  certified assembly of air lines and valves to the tunnel. This pressurization method provides the option of using
  a specific, purified gas rather than compressed air.
  
 Inside the tunnel, in the straight section downstream of the motor and fan (and opposite the test section), is the 
 permanent pitot tube, oriented to face into the flow in the center of the flow. Further downstream, inside each
 of the first two corners are ten curved tubes of 5 cm diameter. These tubes smooth the flow through the turns and 
 prevent large scale separation and turbulence. Between the two corners there is a hexal honeycomb structure to 
 additionally promote smooth flow. After the second turn and upstream of the test section there is a 47 cm diameter
 stilling chamber with another hexal honeycomb flow straightener and a series of four 180 mesh screens. Immediately
 beyond this point and adjacently upstream of the test section is an aluminum liner insert that provides a smooth
 transition from 47 cm section to the 20 cm diameter test section. Downstream of the test section and before the 
 third corner is an aluminum diffuser insert that smoothly transitions an increase from 20 to 30 cm diameter. There
 is a screen following the diffuser to prevent material being circulated into the fan section.
MODEL IDENTIFIER
NAIF INSTRUMENT IDENTIFIER
SERIAL NUMBER
REFERENCES