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Rigorous, Practical Method for Predicting Plume Backflow and Surface Impingement

Award Information

Agency:
National Aeronautics and Space Administration
Branch:
N/A
Award ID:
22882
Program Year/Program:
1994 / SBIR
Agency Tracking Number:
22882
Solicitation Year:
N/A
Solicitation Topic Code:
N/A
Solicitation Number:
N/A
Small Business Information
AERO OPTICS, INC.
655 Deep Valley Drive Suite 335 Rolling Hills Estate, CA 90274
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Woman-Owned: No
Minority-Owned: No
HUBZone-Owned: No
 
Phase 1
Fiscal Year: 1994
Title: Rigorous, Practical Method for Predicting Plume Backflow and Surface Impingement
Agency: NASA
Contract: N/A
Award Amount: $69,986.00
 

Abstract:

Spacecraft surface contamination can result from nozzle-exhaust molecules, droplets, and/or condensate-clusters which expand and scatter to fill the space volume at large angles from the nozzle thrust axis. Only a small fraction of the exhaust products expands to large angles; however, the amount is sufficient to influence the design and performance of spacecraft sensor platforms which are subject to contamination effects. The large-angle plume mass/species distribution functions depend on 1) the interacting effects of pressure/shear forces and diffusion/rarefaction effects during the rapid angular expansion at the nozzle lip and 2) the nozzle boundary layer characteristics upstream of the lip expansion. Current prediction methods include 1) method-of-characteristics for continuum regions and 2) direct simulation Monte Carlo (DSMC) techniques for transitional regions. Composite predictions are cumbersome to implement; extremely high grid resolutions are required to preclude numerical diffusion across steep gradients. A new formulation is proposed which uses an extended form of the Navier-Stokes equations in flow-conformal curvilinear streamtube coordinates (to minimize numerical diffusion effects) with additional source/sink terms (to account for flow rarefaction effects). The formulation provides a unified continuous prediction capability which bridges from the continuum region of the nozzle interior to the rarefied region of the plume backflow.

Principal Investigator:

G. Newton Freeman
3105411933

Business Contact:

Small Business Information at Submission:

Aero Optics, Inc.
655 Deep Valley Drive, Suite 335 Rolling Hill Estat, CA 90274

EIN/Tax ID:
DUNS: N/A
Number of Employees: N/A
Woman-Owned: No
Minority-Owned: No
HUBZone-Owned: No