Ignition sensor, utilizing fluidic oscillator device and its ability to react to flow system's molecular weight and temperature changes, detects propellant ignition. Commercial applications include fields of fire protection equipment and fluidics

Henry, C. S.

English

NASA Technical Reports Server

May 1972
	 B72-10158 
NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new 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. 
Fluidic Ignition Detection 
A unique ignition sensor, utilizing a fluidic oscillator Transducer	 Discharge 
device and its ability to react to a flow system's mole- Signal 
cular weight and temperature changes, can be used to Conditioning 
detect propellant ignition. It may be applied commer- To Controller 
cially in the fields of fire protection equipment and 
fluidics. The oscillator distinguishes various flow phases 
(as shown in Figure 1), which the ignitor experiences 
during a start transient period and presents the ignition- 
no-ignition frequency output characteristics as a go-no- Oscillator 
go signal. The frequency is monitored electronically with  
a high-frequency pressure sensor with the predetermined - 
reactions occurring as a result of the specific frequency 
level or counter state produced. 
The sensor is incorporated into the igniter system, as 
shown in Figure 2. The detector itself may be a separate 
or integral assembly mounted between the igniter body Propellant	 Igniter 
and preburner. Since the oscillator is a continuous flow
Chamber 
device,	 requiring	 a	 finite	 pressure	 drop,	 the	 sensor 
system would have a discharge flow that must be routed Ignition Sensor Assembly Schematic 
to some lower pressure sink. Figure 2. 
The sensor has no moving parts, is ruggedly con-
structed, and appears to be highly reliable. Detection is 
by means of direct measurement, and the system can be Note: 
checked by monitoring the output during a surge flow. Requests for further information may be directed to: 
The output of the detector is readily converted to a Technology Utilization Officer 
digital pulse code. Marshall Space Flight Center 
Code A & TS-TU 
Huntsville, Alabama 35812 
N 
I	 Ignition Reference: B72-10158 
500	 Helium Off	 Oxygen 
Hydrogen On	 On 
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________ Patent status: 
a,
300 
:::
No patent action is contemplated by NASA. 
L Ignition 
co
100	 HeIim On	
-
Source: C. S. Henry of 
Aerojet Liquid Rocket Company 
0 under contract to 
Time 
Fluidic Ignition Detector Marshall Space Flight Center 
Figure 1 • . (MFS-2 1498) 
Category 06
• 
This document was prepared under the sponsorship of the National	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights. 
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Fluidic Ignition Detection

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