Regular and Mach Reflections to Mach 18 with Air and TNT Detonation Products
Abstract
This report describes the computation of critical incident shock wave angles for regular (alpha sub d) reflections as a function of Mach number up to 18. First, the effect of different values for the specific heat ratio (gamma) is examined, and is found that as gamma decreases from 1.4 to 1.2, the value for alpha sub N decreases for regular reflections, and the value for alpha sub d increases, resulting in a significantly larger dual-solution-domain. Next, temperature dependent properties for air were used with standard temperature and pressure inflow conditions. These results were compared with the perfect gas case with gamma set to 1.4, and showed that the variable properties calculation had very little effect on the alpha sub N value. However, variable properties had a significant effect on the alpha sub d value, because Mach reflections represent stronger shock waves with larger temperature jumps across the shock wave. The next set of results compared the air with variable properties results with results using variable properties and TNT detonation products. Again, we found that the alpha sub N followed the perfect gas case closely with gamma set to 1.2 while the alpha sub d value differed substantially from the perfect gas and variable air properties cases. All cases were significantly different from the gamma = 1.4 case. Finally, results were computed for air with variable properties and equilibrium chemistry. We have that alpha sub N was not sensitive to equilibrium chemistry over the entire range of Mach numbers while alpha sub d increased significantly at the higher Mach numbers. At Mach 18, the values for alpha sub N varied between 18.9 degrees (detonation products) and 23.1 degrees (gamma = 1.4), and the values for alpha sub d varied between 39.9 degrees (gamma = 1.4) and 49.2 degrees (detonation products). In general, we found alpha sub N to be fa
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 10, 2008
- Accession Number
- ADA487305
Entities
People
- Douglas Schwer
Organizations
- United States Naval Research Laboratory