External negative feedback system counteracts low frequency oscillations in rocket engine propellant pumps. The system uses a control piston to sense pump discharge fluid on one side and a gas pocket on the other

Rosenmann, W.

English

NASA Technical Reports Server

rI Collar 
terwhirl Collar 
March 1967	 Brief 67-10064 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Negative Feedback System Reduces Pump Oscillations 
Control Pistor
EXTERNAL NEGATIVE FEEDBACK SYSTEM 
The problem: 
To devise a method for counteracting low frequency 
oscillations in rocket engine propellant pumps. Pre-
vious methods such as gas injection and holes in in-
ducer blades to counteract oscillations were only 
partially satisfactory. 
The solution: 
An external negative feedback system which utilizes 
a control piston to sense pump discharge fluid on one 
side and a gas pocket on the other. 
How it's done: 
The system consists of a control piston which dis-
patches control fluid to either the prewhirl collar or 
the counterwhirl collar, as required. The former low-
ers the fluid level and the latter raises the fluid level 
through the pump. The control piston senses pump 
discharge fluid on one side and a gas pocket on the 
other. The gas pocket has enough volume to maintain 
a constant pressure with slight piston motions. 
Notes: 
1. This development is in conceptual stage only, and 
as of date of publication of this Tech Brief, neither 
a model nor prototype has been constructed. 
2. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10064
(continued overleaf) 
This document was prepared under the 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=19670000064 2020-03-11T20:21:53+00:00Z
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: Walter Rosenmann
of North American Aviation, Inc.
under contract to
Marshall Space Flight Center 
(M-FS-1852) 
Brief 67-10064	 Category 05


Negative feedback system reduces pump oscillations

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