Published report discusses feasibility of ultrasonic techniques; neutron techniques; X-radiography; optical devices; gamma ray devices; and conventional displacement sensors. Use of signal transmitters in place of slip rings indicated possible improvement and will be subject of futher study

Ensminger, D.

Grieser, D. R.

Hamilton, D. B.

Kissel, J. W.

Plummer, A. M.

Saccocio, E. J.

English

NASA Technical Reports Server

April 1974	 B73-10518 
•	 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. 
Noncontacting Devices to Indicate Deflection and Vibration of 
Turbopump Internal Rotating Parts 
In the past, prototype turbopumps developed for 
liquid rocket engines had to undergo expensive, compli-
cated tests to determine deflections and vibrations of 
internal parts. Most of these tests required the insertion 
of strain gauges and slip rings into a cryogenic environ-
ment, major disassembly of pump sections to permit the 
placement of various sensors, and the mechanical con-
nection of measuring devices to the high-speed rotating 
parts. 
In an attempt to simplify this testing, a feasibility 
study was performed to evaluate the noncontacting 
devices which would monitor internal turbopump com-
ponents remotely. The study, published in a report, 
discusses the feasibility of the following: 
1. Ultrasonic techniques 
2. Neutron techniques 
3. X-radiography 
4. Optical devices 
S. Radioisotope and gamma ray devices 
6. Conventional displacement sensors 
The ultrasonic approach uses an ultrasonic Doppler 
transducer. This transducer applied to the outer case of 
a turbopump can measure vibration of internal parts 
with a high degree of accuracy so long as there is a liquid 
or a solid path connecting it with the rotated part. 
The neutron technique calls for a directional fast-
neutron detector which was evaluated analytically and 
found feasible. The problem of its expensive develop-
ment, however, remains to be resolved. 
Flash X-rays, pulsed over a 20-nanosecond interval, 
were found feasible for real-time measurements. Com-
mercial units are available which produce X-ray energies 
of 300 kV, 600 kV, and 2 MV, Lower power units 
do not have sufficient energy to penetrate large turbo-
pumps. At the present stage, this technique is limited to 
detection of ±0.125 mm (5 mils) in vibration amplitude.
Among the optical techniques evaluated, light-pipe-
reflectance was selected as the most appropriate one 
because it is easy to apply, it can measure a large range 
of amplitudes, it is not affected by large temperature 
variations, and it does not require accurate reflecting 
surfaces. The method uses a fiber optic probe which is 
inserted through a hole drilled in the turbopump housing. 
The probe is very flexible and can be easily inserted into 
difficult-to-reach locations. 
Radioisotope and gamma ray devices, based on a 
simple Mössbauer analysis, were found to be too 
sensitive for turbopump measurements. 
Conventional displacement sensors, using magnetic 
devices to measure vibration, did not offer any improve-
ments over those in existence. The use of signal trans-
mitters in place of slip rings indicated a possible 
improvement and will be the subject of further study. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&PS-TU 
Marshall Space Flight Center, Alabama 35812 
Reference: B73-10518 
Source: D. B. Hamilton, D. Ensminger,
D. R. Grieser, A. M. Plummer,
E. J. Saccocio, and J. W. Kissel of
Battelle Memorial Institute
under contract to

Marshall Space Flight Center
(MFS-22 678) 
Category 06, 03 
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=19730000518 2020-03-17T07:18:13+00:00Z


Noncontacting devices to indicate deflection and vibration of turbopump internal rotating parts

The research is reported which was conducted to develop devices for measuring vibrations and deflections of parts, such as impellers, shafts, turbine wheels, and inducers in operating turbopumps. Three devices were developed to the breadboard stage: ultrasonic Doppler transducer, flash X-rays, and light-pipe reflectance. It was found that the X-ray technique is applicable to the shaft assembly and the turbine seal of the J-2 pump, and the light-pipe-reflectance device appears to be ideal for cryogenic pump sections

Noncontacting devices to indicate deflection and vibration of turbopump internal rotating parts

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