Parallel-flow wind sensor provides differential pressure output which is nearly linear and relatively insensitive to supply pressure over a wide range of wind velocities. Cross-flow wind sensor outputs are input to a fluidic amplifier to obtain high pressure output for low wind velocities without changing output characteristics

Turek, R. F.

English

NASA Technical Reports Server

November 1970	 Brief 70-10461 
Ll
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nology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Very Low Velocity Flow Sensor Uses Fluidic Techniques 
I Differential 
Compressed Gas	 Pressure Output 
Port 
Wind I	 Receiver \	 /	 Receiver
Differential 
Pressure Output 
Receivers 
Jet
Supply Nozzle 
Nozzles
Compressed Gas 
Figure 1. Parallel Flow Wind Sensor 	 Figure 2. Cross-Flow Sensor Configuration 
Two designs for a versatile low velocity flow sensor 
have been developed that have important potential 
applications in V/STOL aircraft, wind tunnel instru-
mentation, meteorology, and gas flow measurement 
in hazardous atmospheres. 
The parallel-flow configuration, shown in Figure 1, 
provides a differential pressure output as the wind 
velocity varies. Gas from the supply port expands 
through twin nozzles and, in the absence of wind, 
generates equal pressures in the receivers. When the 
wind flows past the sensor, the downwind jet pressure 
increases; simultaneously, the upwind pressure de-
creases. The output of this sensor is nearly linear and 
relatively insensitive to supply pressure over a wide 
range of wind velocities. The differential output 
pressure varies from 0 to 0.3 psi per psig of supply 
pressure as the wind velocity varies from 0 to 90 
ft/sec. 
Figure 2 shows the basic design of a cross-flow 
sensor. Gas expands through a supply nozzle to form 
a jet. Two receivers sense the position of the jet, and
their output pressures change as the cross-wind de-
flects the jet. The difference in output pressures of the. 
two receivers is related to the wind velocity by a 
characteristic square-law calibration curve which 
saturates as the wind speed approaches a critical 
velocity. If the outputs of the cross-flow sensor are 
input to a fluidic operatiQnal amplifier, high pressure 
output may be obtained for low wind velocities with-
out changing the output characteristic. In an actual 
test of this configuration, wind velocities from 1 to 
14 ft/sec varied the output pressure from the fluidic 
amplifier over its full range (6 to 13 psig). 
Notes: 
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and Technical Information 
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https://ntrs.nasa.gov/search.jsp?R=19700000444 2020-03-17T00:48:45+00:00Z
Reference: 
NASA-CR-86352 (N70726580), Fluidic Low 
Speed Wind Sensor Research Study 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: R.F. Turek of
Bowles Engineering Corp. 
under contract to 
Electronics Research Center 
(ERC- 10404) 
Brief 70-10461	 Category 03


Very low velocity flow sensor uses fluidic techniques

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