Computer program analyzes the flow /leakage/ across a sealing dam for the case of steady, laminar, subsonic, isothermal, compressible flow. The analysis considers both parallel sealing-dam surfaces and surfaces with small tilt angles

Smith, P. J.

Zuk, J.

English

NASA Technical Reports Server

July 1970	 Brief 70-10317 
.
NASA TECH BRIEF H 
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 Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Computer Program for Analysis of Flow
Across a Gas Turbine Seal 
The problem: 
To develop a means of designing noncontact face-
sealing dams of the type used in gas turbines. Some 
powerplants, such as advanced jet engines, exceed the 
operating limits for which face-contact seals were 
designed. As a result, noncontact seals have become 
necessary. 
The solution: 
A computer program has been developed to carry 
out an analysis of the flow (leakage) across a sealing 
dam for the case of steady, laminar, subsonic, iso-
thermal, compressible flow. The analysis considers 
both parallel sealing-dam surfaces and surfaces with 
small tilt angles. 
How it's done: 
The program is based on a sealing-dam model, 
which consists of two parallel, concentric, circular 
rings separated by a very narrow gap and rotating at a 
constant speed. The model is limited by the following 
physical constraints: the fluid is homogeneous, com-
pressible, viscous, and Newtonian; the flow is steady 
and laminar; the bulk modulus is ignored; the fluid 
beha,ves as a perfect gas; the entrance region effects 
are negligible; and the fluid film is isothermal. 
The governing equations for compressible-fluid flow 
with constant viscosity are incorporated into the anal-
ysis. The physical constraints applied to the model are
used to simplify these equations before the boundary 
conditions of the specific problem are inserted. 
The program input variables include the dimensions 
of the seal, pressure boundary conditions, and the 
physical properties of the gas. The output includes: 
mass flowrate; pressure and velocity distributions, 
Mach number, force, axial film stiffness, center of 
pressure, rotational and pressure-flow Reynolds num-
bers, Knudsen number, torque, power loss and ap-
proximate temperature rise resulting from viscous 
shearing in a specified film thickness. The output data 
are stated in both English and International units. 
Notes: 
I. The program is written in FORTRAN IV for the 
EBM-7094/7044 DCS. 
2. Inquiries should be made to: 
COSMIC 
Barrow Hall 
University of Georgia 
Athens, Georgia 20601 
Reference: B70-10317 
Patent status: 
No patent action is contemplated by NASA. 
Source: J. Zuk and P. J. Smith 
Lewis Research Center 
(LEW- 10975) 
Category 09 
..
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=19700000305 2020-03-17T00:21:32+00:00Z


Computer program for analysis of flow across a gas turbine seal

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server