Low frequency pressure generator is built to provide sinusoidal driving function in frequency range from 0.05 to 50 Hz for frequency response testing of pressure transducers used in liquid-filled systems. Generator consists of piston-in-cylinder, scotch-yoke mechanism machined into piston, and adjustable eccentric

Curreri, J. S.

English

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LiquidrieTerence 
Transducer
U I ,auiauui.ES 
Under Test 
ess 
on 
Pressure Generator And Test Section 
August 1972	 B72-10477 
•	 NASA TECH BRIEF ra,	 A Lewis Research 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. 
Low Frequency Sinusoidal Pressure Generator 
To Variable 
Speed Motor 
/
•-
A low frequency pressure generator has been built 
to provide a sinusoidal driving function in the frequency 
range from 0.05 to 50 Hz for frequency response testing 
of pressure transducers as used in liquid-filled systems. 
The generator, as shown by the figure, consists mainly 
of a piston-in-cylinder, a scotch-yoke mechanism ma-
chined into the piston, and an adjustable eccentric. When 
the device is coupled to a variable speed motor, the 
scotch yoke acts through the eccentric and transfers the 
rotary motion of the motor to the reciprocating motion 
of the piston. The displacement of the piston is a simple 
harmonic, and thus the pressure variations in the pre-
charged cylinder are sinusodial. The amplitude of the 
pressure variations is determined by the adjustment of 
the eccentric, and the frequency is determined by the 
speed of the motor. 
As illustrated by the figure, the transducer systems 
are attached to the test section, and both are completely 
filled with the process fluid. The input pressure is 
generated in the gaseous medium (air) above the liquid 
in the test section. The pressure is transferred by the 
liquid, and is sensed by the transducer systems. Two 
reference transducers are used, one in the liquid, and 
one in the gas above the liquid. The transducer mounted 
(continued overleaf) 
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.
https://ntrs.nasa.gov/search.jsp?R=19720000476 2020-03-17T03:40:31+00:00Z
in the gaseous medium is used only to show the actual 
output signal of the generator. The liquid reference trans-
ducer is used for the comparison of amplitude ratio and 
phase shift. The resulting dynamic data are processed by 
standard techniques. 
Notes: 
1. The following documentation may be obtained from 
National Technical Information Service 
Springfield, Virginia 22151 
Single Document price $3.00 
(or microfiche $0.95) 
Reference: NASA TN-D-6166 (N71-17605), 
Frequency Response of Two Types of Liquid-
Metal Pressure Transducers with Standoff Tubes
2. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B72-10477 
Patent status: 
No patent action is contemplated by NASA. 
Source: Joseph S. Curreri
Lewis Research Center 
(LEW-1 1465) 
B72-10477	 Category 01


Low frequency sinusoidal pressure generator

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