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Experimental and numerical investigation of an O$_{2}$/NO supersonic free jet expansion

Published online by Cambridge University Press:  03 February 2004

A. BROC
Affiliation:
Istituto di Metodologie Inorganiche e dei Plasmi-CNR, c/o Dipartimento di Chimica Università di Bari, Via Orabona 4, Bari, 70126, Italy Present address: ONERA/DMPH/EAG, BP 72, 29 avenue de la Division Leclerc, 92322 Chatillon Cedex, France.
S. DE BENEDICTIS
Affiliation:
Istituto di Metodologie Inorganiche e dei Plasmi-CNR, c/o Dipartimento di Chimica Università di Bari, Via Orabona 4, Bari, 70126, Italy
G. DILECCE
Affiliation:
Istituto di Metodologie Inorganiche e dei Plasmi-CNR, c/o Dipartimento di Chimica Università di Bari, Via Orabona 4, Bari, 70126, Italy
M. VIGLIOTTI
Affiliation:
Istituto di Metodologie Inorganiche e dei Plasmi-CNR, c/o Dipartimento di Chimica Università di Bari, Via Orabona 4, Bari, 70126, Italy
R. G. SHARAFUTDINOV
Affiliation:
Laboratory of Molecular Kinetics, Institute of Thermophysics SB RAS, 1, Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia
P. A. SKOVORODKO
Affiliation:
Laboratory of Rarefied Gases, Institute of Thermophysics SB RAS, 1, Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia

Abstract

Cold O$_{2}$/NO supersonic expansions through an axisymmetric convergent–divergent nozzle into a low-pressure background gas have been investigated both experimentally and numerically. Temperature and density measurements have been carried out, using tracer NO in an O$_{2}$ main flow. NO two-dimensional rotational temperature and density flow field patterns in the jet behind the nozzle have been measured by laser-induced fluorescence (LIF). The spectroscopic investigations are complemented by static and impact pressure measurements along the jet centreline. Two nozzles with the same inner profile but with a short and long divergent section and small and large lip have been examined. Three experiments performed using these nozzles cover a wide range of regimes of underexpanded free jet flow, from highly oscillating multi-cycle structure to the regime with smooth deceleration of the issuing flow by the background gas. The numerical simulation of the whole flow field from the conditions in the stagnation chamber to those in the flooded space is performed in the framework of the full set of Navier–Stokes equations by employing a recently developed algorithm based on a staggered grid. The flow inside a long nozzle is shown to be strongly affected by the boundary layer, which leads to the degeneration of the isentropic core at the nozzle exit and transforms the jet regime from overexpanded for inviscid flow to underexpanded for a real flow. The model reproduces the experimental structures of the low-density free jet flow fairly well.

Type
Papers
Copyright
© 2004 Cambridge University Press

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