Research Papers: Fundamental Issues and Canonical Flows

One-Dimensional Unsteady Periodic Flow Model with Boundary Conditions Constrained by Differential Equations

[+] Author and Article Information
Nhan T. Nguyen

 NASA Ames Research Center, Moffett Field, CA 94035

J. Fluids Eng 131(6), 061201 (May 12, 2009) (15 pages) doi:10.1115/1.3130244 History: Received November 02, 2007; Revised April 13, 2009; Published May 12, 2009

This paper describes a modeling method for closed-loop unsteady fluid transport systems based on 1D unsteady Euler equations with nonlinear forced periodic boundary conditions. A significant feature of this model is the incorporation of dynamic constraints on the variables that control the transport process at the system boundaries as they often exist in many transport systems. These constraints result in a coupling of the Euler equations with a system of ordinary differential equations that model the dynamics of auxiliary processes connected to the transport system. Another important feature of the transport model is the use of a quasilinear form instead of the flux-conserved form. This form lends itself to modeling with measurable conserved fluid transport variables and represents an intermediate model between the primitive variable approach and the conserved variable approach. A wave-splitting finite-difference upwind method is presented as a numerical solution of the model. An iterative procedure is implemented to solve the nonlinear forced periodic boundary conditions prior to the time-marching procedure for the upwind method. A shock fitting method to handle transonic flow for the quasilinear form of the Euler equations is presented. A closed-loop wind tunnel is used for demonstration of the accuracy of this modeling method.

Copyright © 2009 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Figure 1

Closed-circuit wind tunnel (NASA Ames 11 ft TWT)

Grahic Jump Location
Figure 2

Wind tunnel compressor

Grahic Jump Location
Figure 3

NASA Ames 11 ft TWT Mach number envelope

Grahic Jump Location
Figure 4

Closed-loop transport system

Grahic Jump Location
Figure 5

Compressor pressure ratio

Grahic Jump Location
Figure 6

Wind tunnel discretization

Grahic Jump Location
Figure 7

Compressor speed and inlet guide vane flap angle responses

Grahic Jump Location
Figure 8

Drive motor rotor resistance and inlet guide vane motor voltage

Grahic Jump Location
Figure 9

Test section Mach number response

Grahic Jump Location
Figure 10

Mach number distribution

Grahic Jump Location
Figure 11

Mass flow distribution

Grahic Jump Location
Figure 12

Stagnation pressure distribution

Grahic Jump Location
Figure 13

Stagnation temperature distribution

Grahic Jump Location
Figure 14

Test section Mach number comparison between midpoint discretization and current discretization

Grahic Jump Location
Figure 15

Computed shock location

Grahic Jump Location
Figure 16

Maximum shock location error versus number of grid points

Grahic Jump Location
Figure 17

Initial and final Mach number variations




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In