Greater centrifugal radial growth of the preimpeller hub with respect to the impeller and nut at operating speed alleviates clamping and alignment problems in high speed rotating machinery. Design results in axial tightness and radial piloting of the preimpeller

Dietrich, J. A.

English

NASA Technical Reports Server

NASA TECH BRIEF 
.
Inco 718 Nul
m lmp 
Spline 
Figure 1 (Original Design) 	 Figure 2 (Improved Design) 
September 1969	 Brief 69-10373 
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. 
- 
Improved Design of Item in High Speed Rotating Machinery 
Titanium Preimpeller 
Clamping and alignment problems in high speed 
rotating machinery are the result of axial Poisson's 
contraction of the preimpeller hub. With the original 
design it was not possible to preload the preimpeller 
nut sufficiently to compensate for the contraction. 
This resulted in axial and, therefore, radial looseness 
of the preimpeller with respect to the impeller. The 
improved design, however, is able to compensate for 
the contraction by utilizing the greater centrifugal 
radial growth of the pre.impeller hub with respect to 
the impeller and nut at operating speed. The im-
proved design results in axial tightness and radial 
piloting of the preiinpeller and promises to provide 
a solution to clamping and alignment problems pres-
ent in such high speed rotating equipment as turbo-
pumps, jet engines, axial pumps. 
The new design of the nut and preimpeller hub 
incorporates an angle 4 chosen such that, when corn-
bined with thermal effects, the radial growth of the 
preimpeller hub compensates for its axial Poisson's 
contraction. The improvement is significant in that 
it employs the centrifugal force achieved at operating 
speed to effectively load the preimpeller. Thus, force 
vectors generated at operating speed maintain an 
axial tightness and radial piloting of the preimpeller 
not possible with mechanical locking or loading 
devices. 
Note: 
No further documentation is available. Inquiries 
may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B69-10373
(continued overleal) 
This document was pepred 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=19690000369 2020-03-16T18:14:47+00:00Z
Patent status: 
No patent action is contemplated by NASA. 
Source: J. A. Dietrich of

Rocketdyne, a Division of

North American Rockwell Corporation

under contract to
Marshall Space Flight Center

(MFS-18441) 
Brief 69-10373	 Category 05


Improved design of item in high speed rotating machinery

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