Valve, maintaining constant total flow, is driven mechanically in periodic alterations to yield correspondingly periodic outputs of constant sum. Design is applicable to development of jet flaps for helicopter use and may be useful in a multinozzle system

Egli, W. H.

English

NASA Technical Reports Server

1972	 B72-10120 
NASA TECH BRIEF 
Ames Research Center
	 4r 
NASA Tech Briefs announce now technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Dynamic Valve to Supply Constant Total Thrust

to Two Orifice Jets 
A design has been proposed for a valve that will 
divide gas flow between two orifice jets in propor-
tions varied by an external control while maintaining 
a constant total flow. The valve can supply two var-
iable thrusts with a constant sum, and it can be 
driven mechanically in periodic alternations to yield 
correspondingly periodic outputs of constant sum. 
The characteristics of the valve are determined by 
its geometry, as illustrated in the diagram. The V -
shaped slider block fits into the matching jaws which 
are located at the outlet of a plenum. The jaws are 
vertically adjustable, and are positioned so as to 
develop two passages leading to the outlets. Hori-
zontal movement of the V-block will enlarge one 
passage at the expense of the other but the sum of 
the cross-sectional areas will remain constant for any 
fixed position of the vertically adjustable jaws. 
If the supply pressure is sufficiently high, flow 
through both passages is choked and hence indepen-
dent of downstream conditions. Thus, the mass flow-
ing through the two areas will also have a constant 
SUM. If the outputs are connected to nozzles in which 
flow is also choked, the sum of the thrusts will be 
constant, and if the push rod is driven back and forth 
at a sinusoidal rate, the output thrusts will also vary 
sinusoidally with an amplitude dependent on the am-
plitude of drive and a mean value dependent on the 
mean position of the slider block. The sum of the 
thrusts will have a constant magnitude dependent on 
the aperture provided by the vertically adjustable 
jaws and the plenum pressure. There are two special 
advantages from having the valve and the nozzles
choked: (1) the device provides constant sum of 
thrusts; (2) small variations in flow resistance do not 
affect thrusts. 
Slider Block
	
(Horizontal 
Movement) 
Notes: 
1. This innovation was conceived for application in 
the development of a jet flap for helicopter use. 
The design is based on simplified assumptions, but 
it has the virtue of combining relative accuracy 
with mechanical simplicity. 
2. The device may be useful in a multinozzle system, 
where the constancy of total thrust is important. 
3. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: B72-10120
(continued overleaf) 
Thisdocumentwas prepared underthe sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000120 2020-03-17T03:31:08+00:00Z
Patent status: 
No patent action is contemplated by NASA. 
Source: Werner H. Egli of 
Honeywell, Inc. 
under contract to
Ames Research Center 
(ARC-10239) 
B72-10120	 Category 07


Dynamic valve to supply constant total thrust to two orifice jets

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