Flashback Arrestor for Lean Premixed, Prevaporized, Low NO_x Combustors

Lean premixed, prevaporized (LPP) high temperature combustor designs as explored for Advanced Subsonic Transport (AST) and High Speed Civil Transport (HSCT) combustors can achieve low NO_x emission levels. An enabling device is needed to arrest flashback and inhibit autoignition at high power conditions and during transients (surge and rapid spool down). A novel flashback arrestor design has demonstrated the ability to arrest flashback and inhibit downstream flame holding in a 4.6 cm diameter tubular reactor at full power inlet temperatures (725 °C) using Jet-A fuel at 0.4 ≤ ϕ ≤ 3.5. Several low pressure loss (0.2% to 0.4% at 30 m/s) flashback arrestor designs were developed which arrested flashback at all of the test conditions. Flame holding was also inhibited off the flash arrestor face or within the downstream tube at low velocities (≤ 3 to 6 m/s), thus protecting the flashback arrestor and combustor premixer components. Upstream flow conditions influence the specific configuration based on using either a 45% or 76% upstream geometric blockage. Stationary, lean premixed dry low NO_x gas turbine combustors would also benefit from this low pressure drop flashback arrestor design which can be easily integrated into new and existing designs.