Abstract
The combustion performance of scramjet engines was investigated by gas sampling in Mach 4, 6 and 8 flight conditions. Since gas sampling is based on the assumption that the gas composition is preserved in the sampling process, the critical Damkohler numbers nec- essary to quench reactions in the gas samling probes were evaluated using a reduced kinetic model. The analysis using the phase plane showed that reactions in probes can be extin- guished if the probe Damkohler number is less than about 10. The analytical results were duplicated by numerical calculations using full kinetics. The shock swallowing in sampling probes was examined using numerical simulations for the low-Re flow. These theoretical results were verified by experiments using four kinds of probes with various configurations in a M2.5 supersonic combustor. Based on the results, fine sampling probes with a tip dia- meter less than 0.3 mm are recommended for scramjet testing. The experiments also showed that pitot pressure is more sensitive than wall pressure to combustion in supersonic flow. This implies that the wall pressure distribution may underestimate the combustion ef- ficiency in supersonic combustion ducts.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call