Numerical Characterization Of The Discharge Coefficient In Critical Nozzles

Published

July 1, 1998

Author(s)

Aaron N. Johnson, Pedro I. Espina, John D. Wright, G E. Mattingly, C L. Merkle

Abstract

The discharge coefficient in critical nozzles flowing N₂, Ar, CO₂, and H₂ in the Reynolds Number range (2,000 to 22,000) is studied computationally to assess the capability of Computational Fluid Dynamics (CFD) in assisting experimental calibration. A parametric study is conducted to investigate the effects of the wall thermal boundary condition and gas species on the calibration process. Comparisons between numerical and experimental data are found to be in good agreement. However, similar to existing analytical models, the computational model has difficulty characterizing the discharge coefficient for CO₂. Based on these results, it is concluded that with continued research CFD may have the potential to aid in the calibration of critical nozzles by providing detailed flow field characteristics for operating conditions and nozzle geometries not conducive to experiment.

Proceedings Title

1998 National Conference of Standards Laboratories Workshop & Symposium. Session 4E

Conference Dates

July 19-23, 1998

Conference Title

Proceedings of the 1998 NCSL Workshop and Symposium

Pub Type

Conferences

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Keywords

critical nozzle, discharge coefficient, gas flow, laminar, numerical, sonic

Citation

Johnson, A. , Espina, P. , Wright, J. , Mattingly, G. and Merkle, C. (1998), Numerical Characterization Of The Discharge Coefficient In Critical Nozzles, 1998 National Conference of Standards Laboratories Workshop & Symposium. Session 4E, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=830599 (Accessed October 20, 2025)