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Two-phase flows within systems with ambient pressureIn systems where the design inlet and outlet pressures are maintained above the thermodynamic critical pressure, it is often assumed that two phase flows within the system cannot occur. Designers rely on this simple rule of thumb to circumvent problems associated with a highly compressible two phase flow occurring within the supercritical pressure system along with the uncertainties in rotordynamics, load capacity, heat transfer, fluid mechanics, and thermophysical property variations. The simple rule of thumb is adequate in many low power designs but is inadequate for high performance turbomachines and linear systems, where two phase regions can exist even though outlet pressure is greater than critical pressure. Rotordynamic-fluid-mechanic restoring forces depend on momentum differences, and those for a two phase zone can differ significantly from those for a single-phase zone. Using the Reynolds equation the angular velocity, eccentricity, geometry, and ambient conditions are varied to determine the point of two phase flow incipience.
Document ID
Document Type
Conference Paper
Hendricks, R. C. (NASA Lewis Research Center Cleveland, OH, United States)
Braun, M. J. (Akron Univ. Ohio., United States)
Wheeler, R. L., III (NASA Lewis Research Center Cleveland, OH, United States)
Mullen, R. L. (Case Western Reserve Univ. Cleveland, Ohio., United States)
Date Acquired
August 12, 2013
Publication Date
December 1, 1985
Publication Information
Publication: Instability in Rotating Machinery (date)
Subject Category
Distribution Limits
Work of the US Gov. Public Use Permitted.

Available Downloads

NameType 19860020695.pdf STI

Related Records

IDRelationTitle19860020688Analytic PrimaryInstability in Rotating Machinery