An Investigation of Flame Stability in a Coaxial Dump Combustor
Abstract
An experimental investigation of the flame stability characteristics of a coaxial dump combustion chamber was made. A 6-in. diameter combustor was studied, and the dump plane inlet diameter was varied from 2.5 in. to 5.0 inches Tests were carried out using pre-mixed ethylene/air and JP-4/air. To avoid vitiation effects, a clean-air heater was used to vary the temperature of the inlet air. The temperature levels were generally in the range 1000-1250 R; the corresponding inlet pressure was varied between approximately 10 and 40 psia. Inlet Mach numbers were typically in the range 0.2 to 0.9. The flame stability data were not collapsed by a conventional dump combustor correlation. However, a correlating parameter was derived by modelling the annular recirculation zone as an adiabatic stirred reactor using a one-step chemical reaction. This derived correlating parameter was used to obtain successful correlations. Some tests were performed with additional fuel injection directly into the recirculation zone. Lean extinction limits were determined with varying fractions of the total fuel flow being injected into the recirculation zone. These tests yielded an estimate of the air mass flow fraction entrained into the recirculation zone. Finally, tests were performed using a transparent quartz combustor; it was observed that the combustion process was an oscillatory phenomenon with the reaction zone moving rapidly to and fro along the combustor. A comprehensive review of the literature concerning the flame stability and aerodynamics of coaxial dump combustors was presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 18, 1979
- Accession Number
- ADA107256
Entities
People
- Edward T. Curran
Organizations
- Air Force Institute of Technology