Calculation of supersonic minimum length nozzles for equilibrium flow

Abstract

The method of characteristics (MOC) is used to generate the flow field and inviscid wall contour of a minimum length nozzle (MLN) with a straight sonic line. The method is appropriate for accurate and economical generation of flow fields and preliminary designs. Two-dimensional planar and axisymmetric contours are calculated for an equilibrium gas using a two-characteristic method and a three-characteristic method. Results for the Lighthill ideal dissociating gas model are compared to a more sophisticated real gas model employing more developed energy partition functions. For the planar case both gas models and MOC schemes result in exit conditions that closely agree with those from the NASA CET89 thermoequilibrium code. Limitations of the MOC for computing axisymmetric MLN contours for an equilibrium gas are demonstrated. Variations in flow field properties and design parameters are investigated for the planar case.

Keywords:

• Supersonic
• nozzles
• equilibrium flow
• Lighthill ideal
• dissociating gas
• thermoequilibrium code

^*Address for correspondence: Dept. of Aerospace Engineering Sciences, Campus Box 429, Tel.: [phone]; Fax: [phone]; [email protected].

^*Address for correspondence: Dept. of Aerospace Engineering Sciences, Campus Box 429, Tel.: [phone]; Fax: [phone]; [email protected].

Notes

^*Address for correspondence: Dept. of Aerospace Engineering Sciences, Campus Box 429, Tel.: [phone]; Fax: [phone]; [email protected].