Accession Number:

ADA230356

Title:

A Comparison of Molecular Vibration Modeling for Thermal Nonequilibrium Airflow

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s):

• Moran, Kenneth J.

Report Date:

1990-12-01

Pagination or Media Count:

102.0

Abstract:

The effects of thermal nonequilibrium on flows about blunt-bodies have not been studied numerically in isolation from chemical reactions. Typically, air is modeled as a perfect gas or as a chemically reacting mixture. In the former case, significant errors result at Mach numbers exceeding about 5. However, below Mach numbers around 8, the effects of chemical reactions are negligible. This study analyzes flow about a simple axisymmetric blunt-body at moderate hypersonic speeds Mach numbers between 5-8. A first-order-accurate Roe scheme was used to compute solutions of the Euler equations assuming different gas models perfect gas, thermal equilibrium, and thermal nonequilibrium. Equilibrium and nonequilibrium shock standoff distances deviated 10-15 percent from perfect gas calculations. Nonequilibrium solutions produced striking temperature and density gradients in the stagnation region with a unique hot spot near the shock.

Descriptors:

• *THERMAL PROPERTIES
• COMPUTATIONS
• STANDOFF
• MODELS
• MOLECULAR VIBRATION
• AIR FLOW
• ISOLATION
• THERMAL STABILITY
• REGIONS
• GASES
• SOLUTIONS(GENERAL)
• SHOCK
• CHEMICAL REACTIONS
• ERRORS
• AXISYMMETRIC
• DIFFERENTIAL EQUATIONS
• HOT SPOTS
• NONEQUILIBRIUM FLOW
• MACH NUMBER
• RANGE(DISTANCE)
• HYPERSONIC VELOCITY
• BLUNT BODIES
• GRADIENTS
• STAGNATION
• DENSITY

Subject Categories:

• Fluid Mechanics
• Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE